# Filename: A16c_2D_B2D_serverN.py
# Author: James D. Miller; pet.timetocode.org
# 9:47 PM Fri April 22, 2016

import sys, os
import pygame
import datetime
import math

import commands, platform

import inspect

# PyGame Constants
from pygame.locals import *
from pygame.color import THECOLORS

# PyGame gui
from pgu import gui

# Import the vector class from a local module (in this same directory)
from vec2d_jdm import Vec2D

# Networking
from PodSixNet.Server import Server
from PodSixNet.Channel import Channel
import socket

# Box2D
from Box2D import *

# Argument parsing...
import argparse

#=====================================================================
# Classes
#=====================================================================

class ClientChannel(Channel):
    def __init__(self, *args, **kwargs):
        Channel.__init__(self, *args, **kwargs)
    
    # def Network(self, data):
        # #print "Client State Dictionary:", data
        # #print "Network, data['ID']", data['ID']
        # pass
    
    def Network_CN(self, data):
        #global env
        
        # Store incoming data in the client objects.
        speaking_client_name = 'C' + str(data['ID'])
        
        # Check to make sure that this client is still in the client dictionary.
        if speaking_client_name in env.clients:
            # Mouse controls.
        
            env.clients[speaking_client_name].cursor_location_px = data['mXY']  # mouse x,y
            env.clients[speaking_client_name].buttonIsStillDown = data['mBd']   # mouse button down (true/false)
            env.clients[speaking_client_name].mouse_button = data['mB']         # mouse button number (1,2,3,0)
            
            # Jet controls.
            
            # Make the s key behave as a toggle.
            # If key is up, make it ready to accept the down ('D') event.
            if (data['s'] == 'U'):
                env.clients[speaking_client_name].key_s_onoff = 'ON'
                env.clients[speaking_client_name].key_s = data['s']
            # If getting 'D' from network client and the key is enabled.
            elif (env.clients[speaking_client_name].key_s_onoff == 'ON'):
                env.clients[speaking_client_name].key_s = data['s']
                
            env.clients[speaking_client_name].key_a = data['a']
            env.clients[speaking_client_name].key_d = data['d']
            env.clients[speaking_client_name].key_w = data['w']
            
            # Control for stopping all objects (f for freeze).
            env.clients[speaking_client_name].key_f = data['f']
            
            # Gun controls.
            
            # Make the k key behave as a toggle.
            # If key is up, make it ready to accept the down ('D') event.
            if (data['k'] == 'U'):
                env.clients[speaking_client_name].key_k_onoff = 'ON'
                env.clients[speaking_client_name].key_k = data['k']
            # If getting 'D' from network client and the key is enabled.
            elif (env.clients[speaking_client_name].key_k_onoff == 'ON'):
                env.clients[speaking_client_name].key_k = data['k']
            
            env.clients[speaking_client_name].key_j = data['j']
            env.clients[speaking_client_name].key_l = data['l']
            env.clients[speaking_client_name].key_i = data['i']
            env.clients[speaking_client_name].key_space = data[' ']
            
            # Cursor controls.
            env.clients[speaking_client_name].key_lshift = data['ls']
            env.clients[speaking_client_name].key_t = data['t']
            
            # Keep track of client activity...
            env.clients[speaking_client_name].sendCount += 1
            
    def Close(self):
        print "A network client game pad has been closed."
     
     
class GameServer(Server):
    channelClass = ClientChannel
    
    def __init__(self, *args, **kwargs):
        Server.__init__(self, *args, **kwargs)
        self.client_count = 0
        
    # This runs when each client connects.
    def Connected(self, channel, addr):
        #print 'new connection (channel, addr):', channel, addr
        
        self.client_count += 1
        
        if (self.client_count <= 10):
            channel.Send({"action": "hello", "P_ID":self.client_count})
            client_name = 'C' + str(self.client_count)
            # Make a client and put it in the clients list.
            env.clients[client_name] = Client(env.client_colors[client_name])
            # Add the channel as an attribute of the client. Use this to Send to this client.
            env.clients[client_name].channel = channel
        else:
            channel.Send({"action": "hello", "P_ID":0})

        print "self.client_count =", self.client_count

        
class Client:
    def __init__(self, cursor_color):
        self.cursor_location_px = (0,0)   # x_px, y_px
        self.mouse_button = 1             # 1, 2, or 3
        self.buttonIsStillDown = False
        
        self.channel = 0
        
        # Jet
        self.key_a = "U"
        self.key_s = "U"
        self.key_s_onoff = "ON"
        self.key_d = "U"
        self.key_w = "U"
        
        # Gun
        self.key_j = "U"
        self.key_k = "U"
        self.key_k_onoff = "ON"
        self.key_l = "U"
        self.key_i = "U"
        self.key_space = "U"
        
        # Freeze it
        self.key_f = "U"
        
        # Zoom
        self.key_b = "U"
        self.key_n = "U"
        self.key_m = "U"
        self.key_h = "U"
        self.key_lctrl = 'U'
        
        # Cursor selection modification      #b2d
        self.key_lshift = "U"
        self.key_t = "U"
        
        self.selected_puck = None
        self.COM_selection = None
        self.selection_pointOnPuck_b2d_m = b2Vec2(0,0)  #b2d
        
        self.cursor_color = cursor_color
        self.bullet_hit_count = 0
        self.bullet_hit_limit = 50.0
        
        self.previousSendCount = 0
        self.sendCount = 0
        self.active = False
        
        # Define the nature of the cursor strings, one for each mouse button.
        self.mouse_strings = {'string1':{'c_drag':   2.0, 'k_Npm':   60.0},
                              'string2':{'c_drag':   0.1, 'k_Npm':    2.0},
                              'string3':{'c_drag':  20.0, 'k_Npm': 1000.0}}
        # self.mouse_strings = {'string1':{'c_drag':   0.0, 'k_Npm':   60.0},
                              # 'string2':{'c_drag':   0.0, 'k_Npm':    2.0},
                              # 'string3':{'c_drag':   0.0, 'k_Npm': 1000.0}}

        # Special case for objects selected at nonCOM points. c_rot can control the drag (torque)
        # associated with rotation. c_pnt_drag is applied to a selected object at the local body point of the 
        # cursor-selected object. 
        
        self.mouse_strings_nonCOM = {'string1':{'c_drag':    0.0, 'c_pnt_drag':    2.0, 'c_rot':  0.0, 'k_Npm':     60.0},
                                     'string2':{'c_drag':    0.0, 'c_pnt_drag':    0.1, 'c_rot':  0.0, 'k_Npm':      2.0},
                                     'string3':{'c_drag':    0.0, 'c_pnt_drag':   20.0, 'c_rot':  0.0, 'k_Npm':   1000.0}}
                                        
    def calc_string_forces_on_pucks(self):
        # Calculated the string forces on the selected puck and add to the aggregate
        # that is stored in the puck object.
        
        # First deal with selecting and unselecting.
        # Only check for a selected puck if one isn't already selected. This keeps
        # the puck from unselecting if cursor is dragged off the puck!
        if (self.selected_puck == None):
            if self.buttonIsStillDown:
                # Depending on whether the shift key is down or not, do a COM based selection
                # or use box2d to select the object at a particular point on it.   #b2d
                
                if (self.key_lshift == 'D'):
                    self.COM_selection = False
                    temp = air_table.checkForPuckAtThisPosition_b2d(self.cursor_location_px)
                    self.selected_puck = temp['puck']
                    self.selection_pointOnPuck_b2d_m = temp['b2d_xy_m']
                else:
                    # COM selection
                    self.COM_selection = True
                    self.selected_puck = air_table.checkForPuckAtThisPosition(self.cursor_location_px)        
                    self.selection_pointOnPuck_b2d_m = b2Vec2(0,0)
        
        # If a puck is already selected, unselect it if the mouse button is up.
        else:
            if not self.buttonIsStillDown:
                # Unselect the puck and bomb out of here.
                self.selected_puck.selected = False
                self.selected_puck = None
                self.COM_selection = None
                self.selection_2d_m = Vec2D(0,0)
                return None
        
        # Now calculate the forces on a selected puck.
        if (self.selected_puck != None):
            # Calculate the absolute World position of the selection point. Can't just add the local vector to
            # the center of mass vector. Would have to know the orientation (rotation) of the local coordinate system.
            # So use box2d do that transform for us.    #b2d
            
            selection_b2d_m = self.selected_puck.b2d_body.GetWorldPoint( self.selection_pointOnPuck_b2d_m)
            # body.GetWorldVector(localVector)
            self.selection_2d_m = Vec2D( selection_b2d_m.x, selection_b2d_m.y)
            
            # Use dx difference to calculate the hooks law force being applied by the tether line. 
            # If you release the mouse button after a drag it will fling the puck.
            # This tether force will diminish as the puck gets closer to the mouse point.
            
            stringName = "string" + str(self.mouse_button)
            
            # Limit the acceleration caused by the cursor string if the targeted object is very small (light).
            # Do this with a scaling factor based on the mass of the selected object. This avoids instability
            # in the physics engines that can be caused by large changes in position/velocity in a time step.
            if ((self.mouse_strings_nonCOM[stringName]['k_Npm'] / self.selected_puck.mass_kg) > 10000.0):
                cursor_scaling_factor = 3.0 * self.selected_puck.mass_kg
            else:
                cursor_scaling_factor = 1
            
            # Calculation and aggregation of the cursor forces.
            if self.COM_selection:
                # Spring force
                dx_2d_m = env.ConvertScreenToWorld(Vec2D(self.cursor_location_px)) - self.selected_puck.pos_2d_m
                spring_force_2d_N = dx_2d_m * self.mouse_strings[stringName]['k_Npm'] * cursor_scaling_factor
                self.selected_puck.cursorString_spring_force_2d_N += spring_force_2d_N
                
                # Calculate the drag and then add to the pucks aggregate drag force.
                drag_force_2d_N = (self.selected_puck.vel_2d_mps * -1 * self.mouse_strings[stringName]['c_drag']) * cursor_scaling_factor
                self.selected_puck.cursorString_puckDrag_force_2d_N += drag_force_2d_N
                
            else:
                # NonCOM selection:
                # Spring
                dx_2d_m = env.ConvertScreenToWorld(Vec2D(self.cursor_location_px)) - self.selection_2d_m
                
                # Spring force
                spring_force_2d_N = dx_2d_m * self.mouse_strings_nonCOM[stringName]['k_Npm'] * cursor_scaling_factor
                # Append, this force and the location it is to be applied on the body, to the list on the puck.  #b2d
                self.selected_puck.nonCOM_N.append({'force_2d_N': spring_force_2d_N,'local_b2d_m': self.selection_pointOnPuck_b2d_m})
            
                # Calculate a drag force based on the velocity of the selected point. Apply this drag to the selected point on the body.
                v_selected_pnt_b2d_mps = self.selected_puck.b2d_body.GetLinearVelocityFromLocalPoint( self.selection_pointOnPuck_b2d_m)
                #print "vel of selected point:", v_selected_pnt_b2d_mps
                v_selected_pnt_2d_mps = Vec2D(v_selected_pnt_b2d_mps.x, v_selected_pnt_b2d_mps.y)
                point_drag_2d_N = v_selected_pnt_2d_mps * (-1) * self.mouse_strings_nonCOM[stringName]['c_pnt_drag'] * cursor_scaling_factor
                self.selected_puck.nonCOM_N.append({'force_2d_N':point_drag_2d_N, 'local_b2d_m':self.selection_pointOnPuck_b2d_m})
                
                # Calculate a drag force based on COM velocity and then add to the pucks aggregate drag force.
                drag_force_2d_N = (self.selected_puck.vel_2d_mps * -1 * self.mouse_strings_nonCOM[stringName]['c_drag'])* cursor_scaling_factor
                self.selected_puck.cursorString_puckDrag_force_2d_N += drag_force_2d_N

                # Calculate the drag torque...
                torque_force_N = -1 * self.selected_puck.rotation_speed * self.mouse_strings_nonCOM[stringName]['c_rot'] * cursor_scaling_factor
                self.selected_puck.cursorString_torque_force_Nm += torque_force_N
            
            # Some torque to spin the objects.
            if (self.key_t == 'D'):
                if (self.selected_puck.b2d_body.angularVelocity < 200.0):
                    if (self.key_lshift == 'D'):
                        spin_direction = +1.0
                    else:
                        spin_direction = -1.0
                    self.selected_puck.cursorString_torque_force_Nm = 10.0 * self.selected_puck.mass_kg * spin_direction
                    
            
    def draw_cursor_string(self):
        if self.COM_selection:
            selection_location_2d_m = self.selected_puck.pos_2d_m
        else:
            selection_location_2d_m = self.selection_2d_m
            
        line_points = [env.ConvertWorldToScreen( selection_location_2d_m), self.cursor_location_px]
        if (self.selected_puck != None):
            pygame.draw.line(game_window.surface, self.cursor_color, line_points[0], line_points[1], 1)
            # Draw small circle at selection point.
            radius_px = 2
            pygame.draw.circle(game_window.surface, THECOLORS["red"], line_points[0], radius_px, 0)
                    
    def draw_fancy_server_cursor(self):
        self.draw_server_cursor( self.cursor_color, 0)
        self.draw_server_cursor( THECOLORS["black"], 1)

    def draw_server_cursor(self, color, edge_px):
        cursor_outline_vertices = []
        cursor_outline_vertices.append(  self.cursor_location_px )
        cursor_outline_vertices.append( (self.cursor_location_px[0] + 10,  self.cursor_location_px[1] + 10) )
        cursor_outline_vertices.append( (self.cursor_location_px[0] +  0,  self.cursor_location_px[1] + 15) )
        
        pygame.draw.polygon(game_window.surface, color, cursor_outline_vertices, edge_px)

        
class runningAvg:
    def __init__(self, n_target):
        self.n_in_avg = 0
        self.n_target = n_target
        self.result = 0.0
        self.values = []
        self.total = 0.0
    def update(self, new_value):
        if self.n_in_avg < self.n_target:
            self.total += new_value
            self.n_in_avg += 1
        else:
            # Add the new value and subtract the oldest.
            self.total += new_value - self.values[0]
            # Discard the oldest value.
            self.values.pop(0)
        self.values.append(new_value)
        
        self.result = self.total / float(self.n_in_avg)
        return self.result
      
      
class Puck:
    def __init__(self, pos_2d_m, radius_m, density_kgpm2, puck_color=THECOLORS["grey"], coef_rest=0.85, CR_fixed=False,
                    pinned=False, rect_fixture=False, aspect_ratio=1.0):
        self.radius_m = radius_m
        self.radius_px = int(round(env.px_from_m(self.radius_m * env.viewZoom)))

        self.density_kgpm2 = density_kgpm2    # mass per unit area
        self.mass_kg = self.density_kgpm2 * math.pi * self.radius_m ** 2
        self.coef_rest = coef_rest
        self.CR_fixed = CR_fixed
        self.pos_2d_m = pos_2d_m
        self.vel_2d_mps = Vec2D(0.0,0.0)
        self.rotation_speed = 0.0
        
        self.SprDamp_force_2d_N = Vec2D(0.0,0.0)
        self.jet_force_2d_N = Vec2D(0.0,0.0)
        self.cursorString_spring_force_2d_N = Vec2D(0.0,0.0)
        self.cursorString_puckDrag_force_2d_N = Vec2D(0.0,0.0)
        self.cursorString_torque_force_Nm = 0

        # Non-center of mass (COM).  #b2d
        # This is a list of dictionaries: each dictionary contains a force and a body location
        self.nonCOM_N = []
        
        self.impulse_2d_Ns = Vec2D(0.0,0.0)
        
        self.selected = False
        
        self.color = puck_color
        
        self.client_name = None
        self.jet = None
        self.gun = None
        
        self.hit = False
        self.hitflash_duration_timer_s = 0.0
        # Make the hit flash persist for this number of seconds:
        self.hitflash_duration_timer_limit_s = 0.05
        
        # Bullet data...
        self.bullet = False
        self.birth_time_s = env.time_s
        self.age_limit_s = 3.0
        
        # Create a Box2d puck.
        self.aspect_ratio = aspect_ratio
        self.rect_fixture = rect_fixture
        if (not pinned):
            self.b2d_body = self.create_Box2d_Puck()
        
    # If you print an object instance...
    def __str__(self):
        return "puck: x is %s, y is %s" % (self.pos_2d_m.x, self.pos_2d_m.y)
    
    # Box2d
    def create_Box2d_Puck(self):
        # Create a dynamic body
        dynamic_body = b2_world.CreateDynamicBody(position=b2Vec2(self.pos_2d_m.tuple()), angle=0, 
                                                  linearVelocity=b2Vec2(self.vel_2d_mps.tuple()))
        
        # Surface friction
        coef_friction = air_table.coef_friction_puck
        
        if self.rect_fixture:
            # And add a box fixture onto it.
            dynamic_body.CreatePolygonFixture(box=(self.radius_m, self.radius_m * self.aspect_ratio), density=self.density_kgpm2, 
                                              friction=coef_friction, restitution=self.coef_rest)
                                              
            # Set the mass attribute based on what box2d calculates.
            self.mass_kg = dynamic_body.mass
            
        else:
            # And add a circle fixture onto it.
            dynamic_body.CreateCircleFixture(radius=self.radius_m , density=self.density_kgpm2, 
                                             friction=coef_friction, restitution=self.coef_rest)
        
        # Some fluid drag inside the Box2D engine.
        dynamic_body.linearDamping = 0.0   #0.6
        dynamic_body.angularDamping = 0.0  #0.6
        
        #print "box2d", dynamic_body.mass, dynamic_body.fixtures[0].restitution
        return dynamic_body
    
    # Box2d
    def get_Box2d_XandV(self):
        # Position
        box2d_pos_2d_m = self.b2d_body.GetWorldPoint(b2Vec2(0,0))
        self.pos_2d_m = Vec2D( box2d_pos_2d_m.x, box2d_pos_2d_m.y)
        
        # Velocity
        box2d_vel_2d_m = self.b2d_body.linearVelocity
        self.vel_2d_mps = Vec2D( box2d_vel_2d_m.x, box2d_vel_2d_m.y)
        
        # Rotational speed.
        self.rotation_speed = self.b2d_body.angularVelocity
        #print self.rotation_speed
    
    def draw(self):
        # Convert x,y to pixel screen location and then draw.
        
        self.pos_2d_px = env.ConvertWorldToScreen( self.pos_2d_m)
        #print "draw position", self.pos_px[0], self.pos_px[1]
        
        # Update based on zoom factor
        self.radius_px = int(round(env.px_from_m( self.radius_m)))
        if (self.radius_px < 3):
            self.radius_px = 3
            
        # Just after a hit, fill the whole circle with RED (i.e., thickness = 0).
        if self.hit:
            puck_circle_thickness = 0
            puck_color = THECOLORS["red"]
            self.hitflash_duration_timer_s += dt_render_s
            if self.hitflash_duration_timer_s > self.hitflash_duration_timer_limit_s:
                self.hit = False
        else:
            puck_circle_thickness = 3
            puck_color = self.color
        
        if self.rect_fixture:
            # Box2d
            fixture_shape = self.b2d_body.fixtures[0].shape
            vertices_screen_2d_px = []
            for vertex_object_2d_m in fixture_shape.vertices:
                vertex_world_2d_m = self.b2d_body.transform * vertex_object_2d_m  # Overload operation
                vertex_screen_2d_px = env.ConvertWorldToScreen( Vec2D(vertex_world_2d_m.x, vertex_world_2d_m.y)) # This returns a tuple
                vertices_screen_2d_px.append( vertex_screen_2d_px) # Append to the list.
            pygame.draw.polygon(game_window.surface, puck_color, vertices_screen_2d_px, puck_circle_thickness)
            
        else:
            # Draw main puck body.
            pygame.draw.circle(game_window.surface, puck_color, self.pos_2d_px, self.radius_px, puck_circle_thickness)
            
            # If it's not a bullet and not a rectangle, dray a line on the puck to indicate rotational orientation.
            if ((self.bullet == False) and (self.rect_fixture==False)):
                point_on_radius_b2d_m = self.b2d_body.GetWorldPoint( b2Vec2(0.0, self.radius_m))
                point_on_radius_2d_m = Vec2D( point_on_radius_b2d_m.x, point_on_radius_b2d_m.y)
                point_on_radius_2d_px = env.ConvertWorldToScreen( point_on_radius_2d_m)
                
                point_at_center_b2d_m = self.b2d_body.GetWorldPoint( b2Vec2(0.0, 0.0))
                point_at_center_2d_m = Vec2D( point_at_center_b2d_m.x, point_at_center_b2d_m.y)
                point_at_center_2d_px = env.ConvertWorldToScreen( point_at_center_2d_m)
                
                pygame.draw.line(game_window.surface, puck_color, point_on_radius_2d_px, point_at_center_2d_px, 2)
        
        # Draw life (poor health) indicator circle.
        if (((self.client_name != None) and env.clients[self.client_name].active) or (self.client_name == 'test')) and (not self.bullet):
            spent_fraction = float(env.clients[self.client_name].bullet_hit_count) / float(env.clients[self.client_name].bullet_hit_limit)
            life_radius = spent_fraction * self.radius_px
            if (life_radius > 2.0):
                life_radius_px = int(round(life_radius))
            else:
                life_radius_px = 2
            
            pygame.draw.circle(game_window.surface, THECOLORS["red"], self.pos_2d_px, life_radius_px, 1)
  
  
class RotatingTube:
    def __init__(self, puck):
        # Associate the tube with the puck.
        self.puck = puck
    
        self.color = env.clients[self.puck.client_name].cursor_color
        
        # Degrees of rotation per second.
        #self.rotation_rate_dps = 360.0
        
        # Scaling factors to manage the aspect ratio of the tube.
        self.sf_x = 0.15
        self.sf_y = 0.50
        
        # Notice the counter-clockwise drawing pattern. Four vertices for a rectangle.
        # Each vertex is represented by a vector.
        self.tube_vertices_2d_m = [Vec2D(-0.50 * self.sf_x, 0.00 * self.sf_y), 
                                   Vec2D( 0.50 * self.sf_x, 0.00 * self.sf_y), 
                                   Vec2D( 0.50 * self.sf_x, 1.00 * self.sf_y),
                                   Vec2D(-0.50 * self.sf_x, 1.00 * self.sf_y)]
        
        # Define a normal (1 meter) pointing vector to keep track of the direction of the jet.
        self.direction_2d_m = Vec2D(0.0, 1.0)
        
    def rotate_vertices(self, vertices_2d_m, angle_deg):
        # Put modified vectors in a new list.
        rotated_vertices_2d_m = []
        for vertex_2d_m in vertices_2d_m:
            rotated_vertices_2d_m.append( vertex_2d_m.rotated( angle_deg))
        return rotated_vertices_2d_m
    
    def rotate_everything(self, angle_deg):
        # Rotate the pointer.
        self.direction_2d_m = self.direction_2d_m.rotated( angle_deg)
        
        # Rotate the tube.
        self.tube_vertices_2d_m = self.rotate_vertices( self.tube_vertices_2d_m, angle_deg)
                    
    def convert_from_world_to_screen(self, vertices_2d_m, base_point_2d_m):
        vertices_2d_px = []
        for vertex_2d_m in vertices_2d_m:
            # Calculate absolute position of this vertex.
            vertices_2d_px.append( env.ConvertWorldToScreen( vertex_2d_m + base_point_2d_m))
        return vertices_2d_px
        
    def draw_tube(self, line_thickness=3):
        # Draw the tube on the game-window surface. Establish the base_point as the center of the puck.
        pygame.draw.polygon(game_window.surface, self.color, 
                            self.convert_from_world_to_screen(self.tube_vertices_2d_m, self.puck.pos_2d_m), line_thickness)


class Jet( RotatingTube):
    def __init__(self, puck):
        RotatingTube.__init__(self, puck)
        
        # Degrees of rotation per second.
        self.rotation_rate_dps = 360.0
        
        self.color = THECOLORS["yellow"]
        
        # The jet flame (triangle)
        self.flame_vertices_2d_m =[Vec2D(-0.50 * self.sf_x, 1.02 * self.sf_y), 
                                   Vec2D( 0.50 * self.sf_x, 1.02 * self.sf_y), 
                                   Vec2D(-0.00 * self.sf_x, 1.80 * self.sf_y)]
                                   
        # Scaler magnitude of jet force.
        self.jet_force_N = 1.3 * self.puck.mass_kg * abs(air_table.gON_2d_mps2.y)
        
        # Point everything down for starters.
        self.rotate_everything( 180)
        
    def turn_jet_forces_onoff(self, client_name):
        if (env.clients[client_name].key_w == "D"):
            # Force on puck is in the opposite direction of the jet tube.
            self.puck.jet_force_2d_N = self.direction_2d_m * (-1) * self.jet_force_N
        else:    
            self.puck.jet_force_2d_N = self.direction_2d_m * 0.0
            
    def client_rotation_control(self, client_name):
        if (env.clients[client_name].key_a == "D"):
            self.rotate_everything( +1 * self.rotation_rate_dps * dt_render_s)
        if (env.clients[client_name].key_d == "D"):
            self.rotate_everything( -1 * self.rotation_rate_dps * dt_render_s)
        if (env.clients[client_name].key_s == "D"):
            # Rotate jet tube to be in the same direction as the motion of the puck.
            puck_velocity_angle = self.puck.vel_2d_mps.get_angle()
            current_jet_angle = self.direction_2d_m.get_angle()
            self.rotate_everything(puck_velocity_angle - current_jet_angle)
            
            #self.rotate_everything(180)
            
            # Reset this so it doesn't keep flipping. Just want it to flip the
            # direction once but not keep flipping.
            # This first line is enough to keep the local client from flipping again because
            # the local keyboard doesn't keep sending the "D" event if the key is held down.
            env.clients[client_name].key_s = "U"
            # This second one is also needed for the network clients because they keep
            # sending the "D" until they release the key.
            env.clients[client_name].key_s_onoff = "OFF"
    
    def rotate_everything(self, angle_deg):
        # Rotate the pointer.
        self.direction_2d_m = self.direction_2d_m.rotated( angle_deg)
        
        # Rotate the tube.
        self.tube_vertices_2d_m = self.rotate_vertices( self.tube_vertices_2d_m, angle_deg)
        
        # Rotate the flame.
        self.flame_vertices_2d_m = self.rotate_vertices( self.flame_vertices_2d_m, angle_deg)

    def draw(self):
        # Draw the jet tube.        
        self.draw_tube()
        
        # Draw the red flame.
        if (env.clients[self.puck.client_name].key_w == "D"):
            pygame.draw.polygon(game_window.surface, THECOLORS["red"], 
                                self.convert_from_world_to_screen(self.flame_vertices_2d_m, self.puck.pos_2d_m), 0)
                                
    
class Gun( RotatingTube):
    def __init__(self, puck):
        RotatingTube.__init__(self, puck)
        
        # Degrees of rotation per second.
        self.rotation_rate_dps = 180.0
        
        self.color = env.clients[self.puck.client_name].cursor_color
        
        # Run this method of the RotationTube class to set the initial angle of each new gun.
        self.rotate_everything( 45)
        
        self.bullet_speed_mps = 5.0
        self.fire_time_s = env.time_s
        self.firing_delay_s = 0.1
        self.bullet_count = 0
        self.bullet_count_limit = 10
        self.gun_recharge_wait_s = 2.5
        self.gun_recharge_start_time_s = env.time_s
        self.gun_recharging = False
        
        self.testing_gun = False
    
        self.shield = False
        self.shield_hit = False
        self.shield_hit_duration_s = 0.0
        # Make the hit remove the shield for this number of seconds:
        self.shield_hit_duration_limit_s = 0.05        
        self.shield_hit_count = 0
        self.shield_hit_count_limit = 20
        self.shield_recharging = False
        self.shield_recharge_wait_s = 4.0
        self.shield_recharge_start_time_s = env.time_s
    
    def client_rotation_control(self, client_name):
        if (env.clients[client_name].key_j == "D"):
            self.rotate_everything( +self.rotation_rate_dps * dt_render_s)
        if (env.clients[client_name].key_l == "D"):
            self.rotate_everything( -self.rotation_rate_dps * dt_render_s)
        if (env.clients[client_name].key_k == "D"):
            # Rotate jet tube to be in the same direction as the motion of the puck.
            puck_velocity_angle = self.puck.vel_2d_mps.get_angle()
            current_gun_angle = self.direction_2d_m.get_angle()
            self.rotate_everything(puck_velocity_angle - current_gun_angle)
            
            # Reset this so it doesn't keep flipping. Just want it to flip the
            # direction once but not keep flipping.
            # This first line is enough to keep the local client from flipping again because
            # the local keyboard doesn't keep sending the "D" event if the key is held down.
            env.clients[client_name].key_k = "U"
            # This second one is also needed for the network clients because they keep
            # sending the "D" until they release the key.
            env.clients[client_name].key_k_onoff = "OFF"
    
    def control_firing(self, client_name):
        # Fire only if the shield is off.
        if ((env.clients[client_name].key_i == "D") and (not self.shield)) or self.testing_gun:
            # Fire the gun.
            if ((env.time_s - self.fire_time_s) > self.firing_delay_s) and (not self.gun_recharging):
                self.fire_gun()
                self.bullet_count += 1
                # Timestamp the firing event.
                self.fire_time_s = env.time_s
        
        # Check to see if gun bullet count indicates the need to start recharging.
        if (self.bullet_count > self.bullet_count_limit):
            self.gun_recharge_start_time_s = env.time_s
            self.gun_recharging = True
            self.bullet_count = 0
        
        # If recharged.
        if (self.gun_recharging and (env.time_s - self.gun_recharge_start_time_s) > self.gun_recharge_wait_s):
            self.gun_recharging = False
                
    def fire_gun(self):
        bullet_radius_m = 0.05
        # Set the initial position of the bullet so that it clears (doesn't collide with) the host puck.
        initial_position_2d_m = (self.puck.pos_2d_m +
                                (self.direction_2d_m * (1.1 * self.puck.radius_m + 1.1 * bullet_radius_m)) )
        temp_bullet = Puck(initial_position_2d_m,  bullet_radius_m, 0.3)
        
        # Relative velocity of the bullet: the bullet velocity as seen from the host puck. This is the
        # speed of the bullet relative to the motion of the host puck (host velocity BEFORE the firing of 
        # the bullet).
        bullet_relative_vel_2d_mps = self.direction_2d_m * self.bullet_speed_mps
        
        # Absolute velocity of the bullet.
        temp_bullet.vel_2d_mps = self.puck.vel_2d_mps + bullet_relative_vel_2d_mps
        
        # Also set the velocity of the Box2d puck.
        temp_bullet.b2d_body.linearVelocity = b2Vec2( temp_bullet.vel_2d_mps.tuple())
        
        temp_bullet.bullet = True
        temp_bullet.b2d_body.bullet = True
        temp_bullet.color = env.clients[self.puck.client_name].cursor_color
        temp_bullet.client_name = self.puck.client_name
        
        air_table.pucks.append( temp_bullet)
        
        # Calculate the recoil impulse from firing the gun (opposite the direction of the bullet).
        self.puck.impulse_2d_Ns = bullet_relative_vel_2d_mps * temp_bullet.mass_kg * (-1)
    
    def control_shield(self, client_name):
        if (env.clients[client_name].key_space == "D") and (not self.shield_recharging):
            self.shield = True
        else:
            self.shield = False
        
        # Check to see if the shield hit count indicates the need to start recharging.
        if (self.shield_hit_count > self.shield_hit_count_limit):
            self.shield_recharge_start_time_s = env.time_s
            self.shield = False
            self.shield_recharging = True
            self.shield_hit_count = 0
        
        # If recharged.
        if (self.shield_recharging and (env.time_s - self.shield_recharge_start_time_s) > self.shield_recharge_wait_s):
            self.shield_recharging = False
    
    def draw(self):
        # Draw the gun tube.
        if (self.gun_recharging):
            line_thickness = 3
        else:
            line_thickness = 0
        
        # Draw the jet tube.
        self.draw_tube( line_thickness)
        
        # Draw the shield.
        if (self.shield):
            if self.shield_hit:
                # Don't draw the shield for a moment after the hit. This visualizes the shield hit.
                self.shield_hit_duration_s += dt_render_s
                if (self.shield_hit_duration_s > self.shield_hit_duration_limit_s):
                    self.shield_hit = False
                    
            else:
                pygame.draw.circle(game_window.surface, self.color, self.puck.pos_2d_px, self.puck.radius_px + 6, 4)

                
class Spring:
    def __init__(self, p1, p2, length_m=3.0, strength_Npm=0.5, spring_color=THECOLORS["yellow"], width_m=0.025, drag_c=0.0):
        
        # Optionally this spring can have one end pinned to a vector point. Do this by passing in p2 as a vector.
        if (p2.__class__.__name__ == 'Vec2D'):
            # Create a point puck at the pinning location.
            # The location of this point puck will never change because
            # it is not in the pucks list that is processed by the
            # physics engine.
            p2 = Puck( p2, 1.0, 1.0, pinned=True)
            p2.vel_2d_mps = Vec2D(0.0,0.0)
            length_m = 0.0
        
        self.p1 = p1
        self.p2 = p2
        self.p1p2_separation_2d_m = Vec2D(0,0)
        self.p1p2_separation_m = 0
        self.p1p2_normalized_2d = Vec2D(0,0)
        
        self.length_m = length_m
        self.strength_Npm = strength_Npm
        self.damper_Ns2pm2 = 0.5 #5.0 #0.05
        self.unstretched_width_m = width_m #0.05
        
        self.drag_c = drag_c
        
        self.spring_vertices_2d_m = []
        self.spring_vertices_2d_px = []
        
        self.spring_color = spring_color
        self.draw_as_line = False
    
    def calc_spring_forces_on_pucks(self):
        self.p1p2_separation_2d_m = self.p1.pos_2d_m - self.p2.pos_2d_m
        
        self.p1p2_separation_m =  self.p1p2_separation_2d_m.length()
        
        # The pinned case needs to be able to handle the zero length spring. The 
        # separation distance will be zero when the pinned spring is at rest.
        # This will cause a divide by zero error if not handled here.
        if ((self.p1p2_separation_m == 0.0) and (self.length_m == 0.0)):
            spring_force_on_1_2d_N = Vec2D(0.0,0.0)
        else:
            self.p1p2_normalized_2d = self.p1p2_separation_2d_m / self.p1p2_separation_m
            
            # Spring force:  acts along the separation vector and is proportional to the separation distance.
            spring_force_on_1_2d_N = self.p1p2_normalized_2d * (self.length_m - self.p1p2_separation_m) * self.strength_Npm
        
        # Damper force: acts along the separation vector and is proportional to the relative speed.
        v_relative_2d_mps = self.p1.vel_2d_mps - self.p2.vel_2d_mps
        v_relative_alongNormal_2d_mps = v_relative_2d_mps.projection_onto(self.p1p2_separation_2d_m)
        damper_force_on_1_N = v_relative_alongNormal_2d_mps * self.damper_Ns2pm2
        
        # Net force by both spring and damper
        SprDamp_force_2d_N = spring_force_on_1_2d_N - damper_force_on_1_N
        
        # This force acts in opposite directions for each of the two pucks. Notice the "+=" here, this
        # is an aggregate across all the springs. This aggregate MUST be reset (zeroed) after the movements are
        # calculated. So by the time you've looped through all the springs, you get the NET force, one each ball, 
        # applied of all individual springs.
        self.p1.SprDamp_force_2d_N += SprDamp_force_2d_N * (+1)
        self.p2.SprDamp_force_2d_N += SprDamp_force_2d_N * (-1)
        
        # Add in some drag forces if a non-zero drag coef is specified. These are based on the
        # velocity of the pucks (not relative speed as is the case above for damper forces).
        self.p1.SprDamp_force_2d_N += self.p1.vel_2d_mps * (-1) * self.drag_c
        self.p2.SprDamp_force_2d_N += self.p2.vel_2d_mps * (-1) * self.drag_c
        
    def width_to_draw_m(self):
        width_m = self.unstretched_width_m * (1 + 0.30 * (self.length_m - self.p1p2_separation_m))
        if width_m < (0.05 * self.unstretched_width_m):
            self.draw_as_line = True
            width_m = 0.0
        else:
            self.draw_as_line = False
        return width_m
    
    def draw(self):   
        # Change the width to indicate the stretch or compression in the spring. Note, it's good to 
        # do this outside of the main calc loop (using the rendering timer). No need to do all this each
        # time step.
        
        width_m = self.width_to_draw_m()
        
        # Calculate the four corners of the spring rectangle.
        p1p2_perpendicular_2d = self.p1p2_normalized_2d.rotate90()
        self.spring_vertices_2d_m = []
        self.spring_vertices_2d_m.append(self.p1.pos_2d_m + (p1p2_perpendicular_2d * width_m))
        self.spring_vertices_2d_m.append(self.p1.pos_2d_m - (p1p2_perpendicular_2d * width_m))
        self.spring_vertices_2d_m.append(self.p2.pos_2d_m - (p1p2_perpendicular_2d * width_m))
        self.spring_vertices_2d_m.append(self.p2.pos_2d_m + (p1p2_perpendicular_2d * width_m))
        
        # Transform from world to screen.
        self.spring_vertices_2d_px = []
        for vertice_2d_m in self.spring_vertices_2d_m:
            self.spring_vertices_2d_px.append( env.ConvertWorldToScreen( vertice_2d_m))
        
        # Draw the spring
        if self.draw_as_line == True:
            pygame.draw.aaline(game_window.surface, self.spring_color, env.ConvertWorldToScreen(self.p1.pos_2d_m),
                                                                       env.ConvertWorldToScreen(self.p2.pos_2d_m))
        else:
            pygame.draw.polygon(game_window.surface, self.spring_color, self.spring_vertices_2d_px)


class fwQueryCallback( b2QueryCallback):
    # Checks for objects at particular locations (p) like under the cursor.  #b2d
    
    def __init__(self, p): 
        super(fwQueryCallback, self).__init__()
        self.point = p
        self.fixture = None

    def ReportFixture(self, fixture):
        body = fixture.body
        if body.type == b2_dynamicBody:
            inside=fixture.TestPoint(self.point)
            if inside:
                self.fixture=fixture
                # We found the object, so stop the query
                return False
        # Continue the query
        return True
        
            
class AirTable:
    def __init__(self, walls_dic):
        self.gON_2d_mps2 = Vec2D(-0.0, -9.8)
        self.gOFF_2d_mps2 = Vec2D(-0.0, -0.0)
        self.g_2d_mps2 = self.gOFF_2d_mps2
        self.g_ON = False
        
        self.b2_walls = []
        
        self.pucks = []
        self.puck_dictionary = {}
        self.controlled_pucks = []
        self.springs = []
        self.walls = walls_dic
        self.collision_count = 0
        self.coef_friction_puck = 0.2
        
        self.color_transfer = False
        
        self.stop_physics = False
        self.tangled = False

        # Only do this is you have to. Avoids calls to the collision checker.
        self.collision_checking_enabled = False
        
        self.FPS_display = True
                             
    def draw(self):
        #{"L_m":0.0, "R_m":10.0, "B_m":0.0, "T_m":10.0}
        topLeft_2d_px =   env.ConvertWorldToScreen( Vec2D( self.walls['L_m'],        self.walls['T_m']))
        topRight_2d_px =  env.ConvertWorldToScreen( Vec2D( self.walls['R_m']-0.01,   self.walls['T_m']))
        botLeft_2d_px =   env.ConvertWorldToScreen( Vec2D( self.walls['L_m'],        self.walls['B_m']+0.01))
        botRight_2d_px =  env.ConvertWorldToScreen( Vec2D( self.walls['R_m']-0.01,   self.walls['B_m']+0.01))
        
        pygame.draw.line(game_window.surface, THECOLORS["orangered1"], topLeft_2d_px,  topRight_2d_px, 1)
        pygame.draw.line(game_window.surface, THECOLORS["orangered1"], topRight_2d_px, botRight_2d_px, 1)
        pygame.draw.line(game_window.surface, THECOLORS["orangered1"], botRight_2d_px, botLeft_2d_px,  1)
        pygame.draw.line(game_window.surface, THECOLORS["orangered1"], botLeft_2d_px,  topLeft_2d_px,  1)
    
    def checkForPuckAtThisPosition_b2d(self, x_px_or_tuple, y_px = None):
        # This is used for cursor selection at a particular point on the puck.  #b2d
        # Return the selected puck and also the local point on the puck.
        
        selected_puck = None
        
        if y_px == None:
            self.x_px = x_px_or_tuple[0]
            self.y_px = x_px_or_tuple[1]
        else:
            self.x_px = x_px_or_tuple
            self.y_px = y_px
        
        # Convert to a world point.
        test_position_2d_m = env.ConvertScreenToWorld(Vec2D(self.x_px, self.y_px))
        
        # Convert this to a box2d vector.
        p = test_position_b2d_m = b2Vec2( test_position_2d_m.tuple())
        
        # Make a small box.
        aabb = b2AABB( lowerBound=p-(0.001, 0.001), upperBound=p+(0.001, 0.001))

        # Query the world for overlapping shapes.
        query = fwQueryCallback( p)
        b2_world.QueryAABB( query, aabb)
        
        # If the query was successful and found a body at the cursor point.
        if query.fixture:
            selected_b2d_body = query.fixture.body
            selected_b2d_body.awake = True
        
            # Find the local point in the body's coordinate system.
            local_b2d_m = selected_b2d_body.GetLocalPoint( p)
            #local_b_b2d_m = selected_b2d_body.GetLocalVector( p)
            #print local_b2d_m
        
            # Use a dictionary to identify the puck based on the b2d body.
            # Bullets have not been added to the dictionary.
            if not selected_b2d_body.bullet:
                selected_puck = air_table.puck_dictionary[ selected_b2d_body]
        
            # Return a dictionary with the puck and local selection point on it.
            return {'puck': selected_puck, 'b2d_xy_m': local_b2d_m}
        
        else:
            return {'puck': None, 'b2d_xy_m': b2Vec2(0,0)}
    
    def checkForPuckAtThisPosition(self, x_px_or_tuple, y_px = None):
        if y_px == None:
            self.x_px = x_px_or_tuple[0]
            self.y_px = x_px_or_tuple[1]
        else:
            self.x_px = x_px_or_tuple
            self.y_px = y_px
        
        test_position_2d_m = env.ConvertScreenToWorld(Vec2D(self.x_px, self.y_px))
        for puck in self.pucks:
            vector_difference_m = test_position_2d_m - puck.pos_2d_m
            # Use squared lengths for speed (avoid square root)
            mag_of_difference_m2 = vector_difference_m.length_squared()
            if mag_of_difference_m2 < puck.radius_m**2:
                puck.selected = True
                return puck
        return None

    def update_TotalForceVectorOnPuck(self, puck, dt_s):
        # Net resulting force on the puck.
        puck_forces_2d_N = (self.g_2d_mps2 * puck.mass_kg) + (puck.SprDamp_force_2d_N + 
                                                              puck.jet_force_2d_N +
                                                              puck.cursorString_spring_force_2d_N +
                                                              puck.cursorString_puckDrag_force_2d_N +
                                                              puck.impulse_2d_Ns/dt_s)
        
        # Apply this force to the puck's center of mass (COM) in the Box2d world
        force_point_b2d_m = puck.b2d_body.GetWorldPoint( b2Vec2(0,0))
        force_vector_b2d_N = b2Vec2( puck_forces_2d_N.tuple())
        puck.b2d_body.ApplyForce( force=force_vector_b2d_N, point=force_point_b2d_m, wake=True)
        
        # Apply any non-COM forces.   #b2d
        for force_dict in puck.nonCOM_N:
            force_point_b2d_m = puck.b2d_body.GetWorldPoint( force_dict['local_b2d_m'])
            force_vector_b2d_N = b2Vec2( force_dict['force_2d_N'].tuple())
            puck.b2d_body.ApplyForce( force=force_vector_b2d_N, point=force_point_b2d_m, wake=True)
        
        # Apply torques.   #b2d
        puck.b2d_body.ApplyTorque( puck.cursorString_torque_force_Nm, wake=True)
        
        # Now reset the aggregate forces.
        puck.SprDamp_force_2d_N = Vec2D(0.0,0.0)
        puck.cursorString_spring_force_2d_N = Vec2D(0.0,0.0)
        puck.nonCOM_N = []
        puck.cursorString_puckDrag_force_2d_N = Vec2D(0.0,0.0)
        puck.cursorString_torque_force_Nm = 0.0
        
        puck.impulse_2d_Ns = Vec2D(0.0,0.0)
    
    def check_for_collisions(self):
        # Simplified for Box2d
        
        self.tangled = False        
        
        for i, puck in enumerate(self.pucks):
            
            # Collisions with other pucks. 
            for otherpuck in self.pucks[i+1:]:
                # Check if the two puck circles are overlapping.
                
                # Parallel to the normal
                puck_to_puck_2d_m = otherpuck.pos_2d_m - puck.pos_2d_m
                
                # Keep the following checks fast by avoiding square roots.
                
                # Separation between the pucks, squared (not a vector).
                p_to_p_m2 = puck_to_puck_2d_m.length_squared()
                
                # The sum of the radii of the two pucks, squared.
                r_plus_r_m2 = (puck.radius_m + otherpuck.radius_m)**2
                
                # A check for the Jello-madness game. If it's tangled, balls
                # will be close and this will be set to True.
                if (p_to_p_m2 < 1.1 * r_plus_r_m2):
                    self.tangled = True
                
                if platform.system() == 'Linux':
                    # The RPi needs a little more margin for error to register a bullet collision.
                    enlarging_factor = 1.2
                else:
                    enlarging_factor = 1.0

                # Keep this collision check fast by avoiding square roots.
                if (p_to_p_m2 < enlarging_factor * r_plus_r_m2):
                    self.collision_count += 1
                    #print "collision_count", self.collision_count
                    
                    # If it's a bullet coming from another client, add to the
                    # hit count for non-bullet client.
                    if (puck.client_name != None) and (otherpuck.client_name != None):
                        if (puck.client_name != otherpuck.client_name): 
                            if (otherpuck.bullet and (not puck.bullet)):
                                if not puck.gun.shield:
                                    env.clients[puck.client_name].bullet_hit_count += 1
                                    puck.hit = True
                                    puck.hitflash_duration_timer_s = 0.0
                                else:
                                    puck.gun.shield_hit = True
                                    puck.gun.shield_hit_duration_s = 0.0
                                    puck.gun.shield_hit_count += 1
                                
                                #print puck.client_name, env.clients[puck.client_name].bullet_hit_count, puck.gun.shield_hit_count
    

class Environment:
    def __init__(self, screenSize_px, length_x_m):
        self.screenSize_px = Vec2D(screenSize_px)
        self.viewOffset_2d_px = Vec2D(0,0)
        self.viewCenter_px = Vec2D(0,0)
        self.viewZoom = 1
        self.viewZoom_rate = 0.01
    
        self.px_to_m = length_x_m/float(self.screenSize_px.x)
        self.m_to_px = (float(self.screenSize_px.x)/length_x_m)
        
        self.client_colors = {'C1': THECOLORS["orangered1"],'C2': THECOLORS["tan"],'C3': THECOLORS["cyan"],'C4': THECOLORS["blue"],
                              'C5': THECOLORS["pink"], 'C6': THECOLORS["red"],'C7': THECOLORS["coral"],'C8': THECOLORS["green"],
                              'C9': THECOLORS["grey80"],'C10': THECOLORS["rosybrown3"],'test': THECOLORS["purple"]}
                              
        # Add a local (non-network) client to the client dictionary.
        self.clients = {'local':Client(THECOLORS["green"])}
        self.clients['local'].active = True
        
        # General clock time for determining bullet age.
        self.time_s = 0
        # Timer for the Jello Madness game.
        self.game_time_s = 0
        
        self.loopsSinceLastQuietCheck = 0
        
    def checkForQuietClients(self):
        self.loopsSinceLastQuietCheck += 1
        if self.loopsSinceLastQuietCheck > 20:
            self.loopsSinceLastQuietCheck = 0
            for clientname in self.clients:
                if clientname != 'local':
                    # Check for the no change case (client is quiet).
                    countChange = self.clients[clientname].sendCount - self.clients[clientname].previousSendCount
                    if countChange == 0:
                        self.clients[clientname].active = False
                    else:
                        self.clients[clientname].active = True
                    # Update the previous value for use in the next comparison.
                    self.clients[clientname].previousSendCount = self.clients[clientname].sendCount
                
    def remove_healthless_clients(self):
        # Make a list of terminal clients.
        #print len(air_table.pucks), len(air_table.controlled_pucks)
        
        spent_client_names = []
        for thisclient_name in self.clients:
            if self.clients[thisclient_name].bullet_hit_count > self.clients[thisclient_name].bullet_hit_limit:
                spent_client_names.append( thisclient_name)
                
                # Send the bad news if one of the network clients has died.
                if (thisclient_name not in ['local','test']):
                    self.clients[thisclient_name].channel.Send({"action": "badhealth", "message":"not good"})
                
                print "\"" + thisclient_name + "\"" + " has been popped. "
                
                # Reset the counter for the local client. That will keep this block from running repeatedly
                # when the local puck gets popped. Have to do this because the local client does not get
                # deleted below. That's so it can continue to receive keyboard and mouse input and reset the game
                # if needed. The local client always lives on even if its puck gets popped.
                if thisclient_name == 'local':
                    self.clients[thisclient_name].bullet_hit_count = 0
                
        pucks_list_copy = air_table.pucks[:]
        for puck in pucks_list_copy:
            if puck.client_name in spent_client_names:
                # Had to put this check in to prevent server crash on simultaneous death bullets between two clients.
                # Don't yet understand why this is necessary.
                
                # First remove the puck in Box2d.
                b2_world.DestroyBody(puck.b2d_body)
                
                if (puck in air_table.controlled_pucks):
                    air_table.controlled_pucks.remove( puck)
                    #print "\"" + puck.client_name + "\"" + " has been removed from the controlled puck list."
                
                air_table.pucks.remove( puck)
        
        for spent_client in spent_client_names:
            # Remove client from client dictionary
            if (spent_client != 'local'):
                del self.clients[ spent_client]
              
        del pucks_list_copy
    
    # Convert from meters to pixels 
    def px_from_m(self, dx_m):
        return dx_m * self.m_to_px * self.viewZoom
    
    # Convert from pixels to meters
    # Note: still floating values here)
    def m_from_px(self, dx_px):
        return float(dx_px) * self.px_to_m / self.viewZoom
    
    def control_zoom_and_view(self):
        if self.clients['local'].key_h == "D":
            self.viewZoom += self.viewZoom_rate * self.viewZoom
        if self.clients['local'].key_n == "D":
            self.viewZoom -= self.viewZoom_rate * self.viewZoom
    
    def ConvertScreenToWorld(self, point_2d_px):
        #self.viewOffset_2d_px = self.viewCenter_px
        x_m = (                       point_2d_px.x + self.viewOffset_2d_px.x) / (self.m_to_px * self.viewZoom)
        y_m = (self.screenSize_px.y - point_2d_px.y + self.viewOffset_2d_px.y) / (self.m_to_px * self.viewZoom)
        return Vec2D( x_m, y_m)

    def ConvertWorldToScreen(self, point_2d_m):
        """
        Convert from world to screen coordinates (pixels).
        In the class instance, we store a zoom factor, an offset indicating where
        the view extents start at, and the screen size (in pixels).
        """

        # self.viewOffset = self.viewCenter - self.screenSize_px/2
        #self.viewOffset = self.viewCenter_px
        x_px = (point_2d_m.x * self.m_to_px * self.viewZoom) - self.viewOffset_2d_px.x
        y_px = (point_2d_m.y * self.m_to_px * self.viewZoom) - self.viewOffset_2d_px.y
        y_px = self.screenSize_px.y - y_px

        # Return a tuple of integers.
        return Vec2D(x_px, y_px, "int").tuple()

    def get_local_user_input(self):
        local_user = self.clients['local']
        
        # Get all the events since the last call to get().
        for event in pygame.event.get():
            if (event.type == pygame.QUIT): 
                sys.exit()
            elif (event.type == pygame.KEYDOWN):
                #print "keydown event"
                if (event.key == K_ESCAPE):
                    sys.exit()
                elif (event.key==K_1):            
                    return 1           
                elif (event.key==K_2):                          
                    return 2
                elif (event.key==K_3):
                    return 3           
                elif (event.key==K_4):
                    return 4           
                elif (event.key==K_5):
                    return 5
                elif (event.key==K_6):
                    return 6
                elif (event.key==K_7):
                    return 7
                elif (event.key==K_8):
                    return 8
                elif (event.key==K_9):
                    return 9
                elif (event.key==K_0):
                    return 0
                
                elif (event.key==K_c):
                    # Toggle color option.
                    air_table.color_transfer = not air_table.color_transfer
                    #form['ColorTransfer'].value = air_table.color_transfer
                
                elif (event.key==K_f):
                    # Stop all the pucks...
                    for puck in air_table.pucks:
                        puck.vel_2d_mps = Vec2D(0,0)
                        # And for the Box2d puck.
                        puck.b2d_body.linearVelocity = b2Vec2(0,0)
                
                elif (event.key==K_r):
                    # Stop all the puck rotation...
                    for puck in air_table.pucks:
                        puck.b2d_body.angularVelocity = 0.0
                
                elif (event.key==K_g):
                    # Toggle the logical flag for g.
                    air_table.g_ON = not air_table.g_ON
                    print "g", air_table.g_ON
                    
                    if air_table.g_ON:
                        air_table.g_2d_mps2 = air_table.gON_2d_mps2
                        # Box2d...
                        for eachpuck in air_table.pucks:
                            eachpuck.b2d_body.fixtures[0].restitution = eachpuck.coef_rest
                            eachpuck.b2d_body.fixtures[0].friction    = air_table.coef_friction_puck
                    else:
                        air_table.g_2d_mps2 = air_table.gOFF_2d_mps2
                        # Box2d...
                        for eachpuck in air_table.pucks:
                            if not eachpuck.CR_fixed:
                                eachpuck.b2d_body.fixtures[0].restitution = 1.0
                            eachpuck.b2d_body.fixtures[0].friction    = 0
                    
                
                elif (event.key==K_F1):
                    # Toggle FPS display on/off
                    air_table.FPS_display = not air_table.FPS_display
                
                # Jet keys
                elif (event.key==K_a):
                    local_user.key_a = 'D'
                elif (event.key==K_s):
                    local_user.key_s = 'D'
                elif (event.key==K_d):
                    local_user.key_d = 'D'
                elif (event.key==K_w):
                    local_user.key_w = 'D'
                
                # Gun keys
                elif (event.key==K_j):
                    local_user.key_j = 'D'
                elif (event.key==K_k):
                    local_user.key_k = 'D'
                elif (event.key==K_l):
                    local_user.key_l = 'D'
                elif (event.key==K_i):
                    local_user.key_i = 'D'
                elif (event.key==K_SPACE):
                    local_user.key_space = 'D'
                    
                # Zoom keys
                elif (event.key==K_b):
                    local_user.key_b = 'D'
                elif (event.key==K_n):
                    local_user.key_n = 'D'
                elif (event.key==K_m):
                    local_user.m = 'D'
                elif (event.key==K_h):
                    #print "h--> D"
                    local_user.key_h = 'D'
                elif (event.key==K_LCTRL):
                    #print "lctrl--> D"
                    local_user.key_lctrl = 'D'
                    
                # Control physics for Jello Madness
                elif (event.key==K_p):
                    air_table.stop_physics = not air_table.stop_physics
                    if (not air_table.stop_physics):
                        env.game_time_s = 0                    
                
                # For modifying cursor selection. #b2d
                elif (event.key==K_LSHIFT):
                    #print "lshift--> D"
                    local_user.key_lshift = 'D'
                elif (event.key==K_t):
                    local_user.key_t = 'D'
                
                else:
                    return "nothing set up for this key"
            
            elif (event.type == pygame.KEYUP):
                # Jet keys
                if   (event.key==K_a):
                    local_user.key_a = 'U'
                elif (event.key==K_s):
                    local_user.key_s = 'U'
                elif (event.key==K_d):
                    local_user.key_d = 'U'
                elif (event.key==K_w):
                    local_user.key_w = 'U'
                
                # Gun keys
                elif (event.key==K_j):
                    local_user.key_j = 'U'
                elif (event.key==K_k):
                    local_user.key_k = 'U'
                elif (event.key==K_l):
                    local_user.key_l = 'U'
                elif (event.key==K_i):
                    local_user.key_i = 'U'
                elif (event.key==K_SPACE):
                    local_user.key_space = 'U'
                    
                # Zoom keys
                elif (event.key==K_b):
                    local_user.key_b = 'U'
                elif (event.key==K_n):
                    local_user.key_n = 'U'
                elif (event.key==K_m):
                    local_user.key_m = 'U'
                elif (event.key==K_h):
                    local_user.key_h = 'U'
                elif (event.key==K_LCTRL):
                    #print "lctrl--> U"
                    local_user.key_lctrl = 'U'
                    
                # Cursor selection modification
                #b2d    
                elif (event.key==K_LSHIFT):
                    local_user.key_lshift = 'U'
                elif (event.key==K_t):
                    local_user.key_t = 'U'
                    
            elif event.type == pygame.MOUSEBUTTONDOWN:
                local_user.buttonIsStillDown = True
            
                (button1, button2, button3) = pygame.mouse.get_pressed()
                if button1:
                    local_user.mouse_button = 1
                elif button2:
                    local_user.mouse_button = 2
                elif button3:
                    local_user.mouse_button = 3
                else:
                    local_user.mouse_button = 0
            
            elif event.type == pygame.MOUSEBUTTONUP:
                local_user.buttonIsStillDown = False
                local_user.mouse_button = 0
                
            elif ((event.type == pygame.MOUSEMOTION) and (local_user.key_lctrl == 'D')):
                #print "in mousemotion block", event.pos, event.rel[0], event.rel[1]
                self.viewOffset_2d_px -= Vec2D(event.rel[0], -event.rel[1])
            
            # In all cases, pass the event to the Gui.
            #app.event(event)
        
        if local_user.buttonIsStillDown:
            # This will select a puck when the puck runs into the cursor of the mouse with it's button still down.
            local_user.cursor_location_px = (mouseX, mouseY) = pygame.mouse.get_pos()

        
class GameWindow:
    def __init__(self, screen_tuple_px, title):
        self.width_px = screen_tuple_px[0]
        self.height_px = screen_tuple_px[1]
        
        # The initial World position vector of the Upper Right corner of the screen.
        # Yes, that's right y_px = 0 for UR.
        self.UR_2d_m = env.ConvertScreenToWorld(Vec2D(self.width_px, 0))
        
        # Create a reference to the display surface object. This is a pygame "surface".
        # Screen dimensions in pixels (tuple)
        self.surface = pygame.display.set_mode(screen_tuple_px)

        self.update_caption(title)
        
        self.surface.fill(THECOLORS["black"])
        pygame.display.update()
        
    def update_caption(self, title):
        pygame.display.set_caption( title)
        self.caption = title
    
    def update(self):
        pygame.display.update()
        
    def clear(self):
        # Useful for shifting between the various demos.
        self.surface.fill(THECOLORS["black"])
        pygame.display.update()

        
#===========================================================
# Functions
#===========================================================
        
def make_some_pucks(resetmode):
    game_window.update_caption("PyBox2D Air Table V.3: Demo #" + str(resetmode)) 
    
    if resetmode == 1:
        #                       position            ,radius,density
        air_table.pucks.append( Puck(Vec2D(2.5, 7.5), 0.25, 0.3, THECOLORS["orange"]))
        air_table.pucks.append( Puck(Vec2D(6.0, 2.5), 0.45, 0.3)) # maybe not.
        air_table.pucks.append( Puck(Vec2D(7.5, 2.5), 0.65, 0.3)) 
        air_table.pucks.append( Puck(Vec2D(2.5, 5.5), 1.65, 0.3))
        air_table.pucks.append( Puck(Vec2D(7.5, 7.5), 0.95, 0.3))
    
    
    elif resetmode == 2:
        spacing_factor = 2.0
        grid_size = 4,2
        for j in range(grid_size[0]):
            for k in range(grid_size[1]):
                if ((j,k) == (1,1)):
                    puck_color_value = THECOLORS["orange"]
                else:
                    puck_color_value = THECOLORS["grey"]
                
                air_table.pucks.append( Puck(Vec2D(spacing_factor*(j+1), spacing_factor*(k+1)), 0.75, 0.3, puck_color=puck_color_value))
    
    
    elif resetmode == 3:
        spacing_factor = 1.5
        grid_size = 5,3
        for j in range(grid_size[0]):
            for k in range(grid_size[1]):
                if ((j,k) == (2,2)):
                    puck_color_value = THECOLORS["orange"]
                else:
                    puck_color_value = THECOLORS["grey"]

                air_table.pucks.append( Puck(Vec2D(spacing_factor*(j+1), spacing_factor*(k+1)), 0.55, 0.3, puck_color=puck_color_value))

    
    elif resetmode == 4:
        spacing_factor = 1.0      
        
        if platform.system() == 'Linux':
            grid_size = 5,4
        else:    
            grid_size = 7,7
        
        for j in range(grid_size[0]):
            for k in range(grid_size[1]):
                if ((j,k) == (2,2)):
                    puck_color_value = THECOLORS["orange"]
                else:
                    puck_color_value = THECOLORS["grey"]
                
                air_table.pucks.append( Puck(Vec2D(spacing_factor*(j+1), spacing_factor*(k+1)), radius_m=0.25, density_kgpm2=1.0, 
                                             puck_color=puck_color_value,
                                             CR_fixed=False, coef_rest=0.9) )
    
    
    elif resetmode == 5:
        air_table.pucks.append( Puck(Vec2D(2.00, 3.00),  0.4, 0.3) )
        air_table.pucks.append( Puck(Vec2D(3.50, 4.50),  0.4, 0.3) )
        
        # No springs on this one.
        #air_table.pucks.append( Puck(Vec2D(3.50, 7.00),  0.95, 0.3) )
    
        spring_strength_Npm2 = 20.0 #18.0
        spring_length_m = 1.5
        air_table.springs.append( Spring(air_table.pucks[0], air_table.pucks[1], spring_length_m, spring_strength_Npm2, width_m=0.2))
    
                    
    elif resetmode == 6:
        
        if platform.system() == 'Linux':
            density = 2.0
            radius = 0.7
            
            # Lower the CR for these pucks and fix them, using CR_fixed, so when gravity 
            # toggles on/off they stay at these levels.
            coef_rest_puck =  0.50
            
            spring_strength_Npm2 = 300.0
            spring_length_m = 2.5
            spring_width_m = 0.07
            spring_drag = 0.0
            spring_damper = 10.0
        else:
            density = 1.5
            radius = 0.7
            
            coef_rest_puck =  0.70
            
            spring_strength_Npm2 = 400.0
            spring_length_m = 2.5
            spring_width_m = 0.07
            spring_drag = 0.0
            spring_damper = 5.0

        air_table.pucks.append( Puck(Vec2D(2.00, 3.00),  radius, density, coef_rest=coef_rest_puck, CR_fixed=True) )
        air_table.pucks.append( Puck(Vec2D(3.50, 4.50),  radius, density, coef_rest=coef_rest_puck, CR_fixed=True) )
        air_table.pucks.append( Puck(Vec2D(5.00, 3.00),  radius, density, coef_rest=coef_rest_puck, CR_fixed=True) )
        
        # No springs on this one.
        air_table.pucks.append( Puck(Vec2D(3.50, 7.00),  0.95, density, coef_rest=coef_rest_puck, CR_fixed=True) )
        
        air_table.springs.append( Spring(air_table.pucks[0], air_table.pucks[1],
                                         spring_length_m, spring_strength_Npm2, width_m=spring_width_m, drag_c=spring_drag))
        air_table.springs.append( Spring(air_table.pucks[1], air_table.pucks[2],
                                         spring_length_m, spring_strength_Npm2, width_m=spring_width_m, drag_c=spring_drag))
        air_table.springs.append( Spring(air_table.pucks[2], air_table.pucks[0],
                                         spring_length_m, spring_strength_Npm2, width_m=spring_width_m, drag_c=spring_drag))
        
        # Increase the shock-absorber strength for each spring.
        for spring in air_table.springs:                                 
            spring.damper_Ns2pm2 = spring_damper
            
            
    elif resetmode == 7:
        air_table.collision_checking_enabled = True
        env.game_time_s = 0    
        offset_xy_m = Vec2D(2.5, 2.1) 
        
        if platform.system() == 'Linux':
            spacing_factor = 1.0
            grid_size = 3
            density = 45.0
            radius = 0.25
            spring_strength_Npm2 = 800.0 #18.0
            spring_length_m = 1.2
            spring_damper_Ns2pm2 = 5.0
        else:
            spacing_factor = 1.0
            grid_size = 4 
            density = 5.0
            radius = 0.25 
            spring_strength_Npm2 = 800.0 #18.0
            spring_length_m = 1.2            
            spring_damper_Ns2pm2 = 5.0
        
        grid = grid_size, grid_size
        
        for j in range(grid[0]):
            for k in range(grid[1]):
                if ((j,k) == (2,2)):
                    air_table.pucks.append( Puck(Vec2D(spacing_factor*(j+1), spacing_factor*(k+1)) + offset_xy_m, radius, density, THECOLORS["orange"]))
                else:
                    air_table.pucks.append( Puck(Vec2D(spacing_factor*(j+1), spacing_factor*(k+1)) + offset_xy_m, radius, density))
        
        for m in range(grid_size*(grid_size-1)):
            air_table.springs.append( Spring(air_table.pucks[m], air_table.pucks[m+grid_size], spring_length_m, spring_strength_Npm2, spring_color=THECOLORS["blue"]))
        
        for m in range(grid_size-1):
            for n in range(grid_size):
                o_index = m + (n * grid_size)
                #print "index:", m, n, o_index, o_index+1
                air_table.springs.append( Spring(air_table.pucks[o_index], air_table.pucks[o_index+1], spring_length_m, spring_strength_Npm2, spring_color=THECOLORS["blue"]))
        
        for m in range(0, grid_size-1):
            for n in range(1, grid_size):
                o_index = m + (n * grid_size)
                air_table.springs.append( Spring(air_table.pucks[o_index], air_table.pucks[o_index-(grid_size-1)], spring_length_m, spring_strength_Npm2, spring_color=THECOLORS["yellow"]))
        
        for m in range(0, grid_size-1):
            for n in range(0, grid_size-1):
                o_index = m + (n * grid_size)
                air_table.springs.append( Spring(air_table.pucks[o_index], air_table.pucks[o_index+(grid_size+1)], spring_length_m, spring_strength_Npm2, spring_color=THECOLORS["yellow"]))

        # Increase the shock-absorber strength for each spring.
        for spring in air_table.springs:                                
            spring.damper_Ns2pm2 = spring_damper_Ns2pm2                
                
                
    elif resetmode == 8:        
        air_table.collision_checking_enabled = True
        
        if platform.system() == 'Linux':
            # for Raspberry Pi
            density = 1.0
            
            #                                           ,radius,density
            air_table.pucks.append( Puck(Vec2D(5.0, 2.5), 0.30, density, rect_fixture=True))
            air_table.pucks.append( Puck(Vec2D(5.0, 2.5), 0.30, density))
            air_table.pucks.append( Puck(Vec2D(7.5, 2.5), 0.65, density, rect_fixture=True))
            air_table.pucks.append( Puck(Vec2D(7.5, 5.5), 0.95, density, rect_fixture=True))
            #air_table.pucks.append( Puck(Vec2D(2.5, 5.5), 1.65, density))
            air_table.pucks.append( Puck(Vec2D(7.5, 7.5), 0.95, density))

            # Make some pinned-spring pucks.
            for m in range(0, 3): 
                pinPoint_2d = Vec2D(2.0 + float(m) * 1.65, 4.0)
                tempPuck = Puck(pinPoint_2d, 0.7, density*5.0,  THECOLORS["orange"])
                air_table.pucks.append( tempPuck)
                air_table.springs.append( Spring(tempPuck, pinPoint_2d, strength_Npm=300.0, width_m=0.02, drag_c = 1.5 + 10.0))
        else:
            density = 0.7
            
            #                                           ,radius,density
            air_table.pucks.append( Puck(Vec2D(5.0, 2.5), 0.15, density, rect_fixture=True))
            air_table.pucks.append( Puck(Vec2D(5.0, 2.5), 0.15, density, rect_fixture=False))
            air_table.pucks.append( Puck(Vec2D(7.5, 2.5), 0.65, density, rect_fixture=True))
            air_table.pucks.append( Puck(Vec2D(7.5, 5.5), 0.95, density, rect_fixture=True))
            #air_table.pucks.append( Puck(Vec2D(2.5, 5.5), 1.65, density))
            air_table.pucks.append( Puck(Vec2D(7.5, 7.5), 0.95, density))

            # Make some pinned-spring pucks.
            for m in range(0, 6): 
                pinPoint_2d = Vec2D(2.0 + float(m) * 0.65, 4.0)
                tempPuck = Puck(pinPoint_2d, 0.25, density,  THECOLORS["orange"])
                air_table.pucks.append( tempPuck)
                air_table.springs.append( Spring(tempPuck, pinPoint_2d, strength_Npm=300.0, width_m=0.02, drag_c=1.5))
        
        # Make user/client controllable pucks
        # for all the clients.
        y_puck_position_m = 1.0
        for client_name in env.clients:
            if env.clients[client_name].active:
                tempPuck = Puck(Vec2D(6.0, y_puck_position_m), 0.45, density)
                # Let the puck reference the jet and the jet reference the puck.
                tempPuck.client_name = client_name
                tempPuck.jet = Jet( tempPuck)
                tempPuck.gun = Gun( tempPuck)

                air_table.pucks.append( tempPuck)
                air_table.controlled_pucks.append( tempPuck)
                y_puck_position_m += 1.2
                
                # Reset the hit counters.
                env.clients[client_name].bullet_hit_count = 0
        
        # Keep gun on in a testing puck...
        if args.testPuck == 'on':
            tempPuck = Puck(Vec2D(6.0, y_puck_position_m), 0.45, density)
            # Let the puck reference the jet and the jet reference the puck.
            tempPuck.client_name = "test"
            env.clients[tempPuck.client_name] = Client(env.client_colors[tempPuck.client_name])
            tempPuck.jet = Jet( tempPuck)
            tempPuck.gun = Gun( tempPuck)
            tempPuck.gun.testing_gun = True
            # The default position at instantiation is 45 degrees counter-clockwise from vertical.
            # The degree value specified here is relative to that +45. Negative values are clockwise.
            tempPuck.gun.rotate_everything( -110)
            air_table.pucks.append( tempPuck)
            air_table.controlled_pucks.append( tempPuck)
        
        
    elif resetmode == 9:
        # Make user/client controllable pucks
        # for all the clients.
        y_puck_position_m = 1.0
        for client_name in env.clients:
            if env.clients[client_name].active:
                tempPuck = Puck(Vec2D(6.0, y_puck_position_m), 0.45, 0.3)
                # Let the puck reference the jet and the jet reference the puck.
                tempPuck.client_name = client_name
                tempPuck.jet = Jet( tempPuck)
                tempPuck.gun = Gun( tempPuck)

                air_table.pucks.append( tempPuck)
                air_table.controlled_pucks.append( tempPuck)
                y_puck_position_m += 1.2
    
    
    elif resetmode == 0:        
        # Make user/client controllable pucks
        # for all the clients.
        density = 0.7
        width_m = 0.01
        aspect_ratio = 9.0
        x_position_m = 0.3
        for j in range(0, 9):
            y_puck_position_m = (width_m * aspect_ratio / 1.0) + 0.1
            air_table.pucks.append( Puck(Vec2D(x_position_m, y_puck_position_m), width_m, density, rect_fixture=True, aspect_ratio=aspect_ratio))
            width_m *= 1.5
            x_position_m *= 1.5
    
    else:
        print "Nothing set up for this key."
    
    # Make a dictionary of the pucks so you can find a puck based on the b2d body.
    for puck in air_table.pucks:
        air_table.puck_dictionary[puck.b2d_body] = puck
        

def display_number(numeric_value, font_object,  mode='FPS'):
    if mode=='FPS':
        # Small background rectangle for FPS text
        pygame.draw.rect(game_window.surface, THECOLORS["white"], pygame.Rect(10, 10, 35, 20))
        # The text
        fps_string = "%.0f" % numeric_value
        txt_surface = font_object.render(fps_string, True, THECOLORS["black"])
        game_window.surface.blit(txt_surface, [18, 11])
    elif mode=='gameTimer':
        # The text
        fps_string = "%.2f" % numeric_value
        txt_surface = font_object.render(fps_string, True, THECOLORS["white"])
        game_window.surface.blit(txt_surface, [600, 11])
        
        
#============================================================
# Main procedural script.
#============================================================

def main():

    # A few globals.
    global env, game_window, air_table, b2_world, args, dt_render_s
    
    # Parse parameters provided in the command line.
    # This description string (and parameter help) gets displayed if help is requested (-h added after the filename).
    parser = argparse.ArgumentParser(description='Please add optional client parameters after the file name. For example: \n' + 
                                                 'A16c_2D_B2D_serverN.py off')
    # An optional positional argument.
    parser.add_argument('testPuck', type=str, nargs='?', default='on', help='Please indicate whether the practice puck should be on or off (default is on).')                              
                                    
    args = parser.parse_args()
    print "testPuck:", args.testPuck
    
    pygame.init()

    myclock = pygame.time.Clock()

    if platform.system() == 'Linux':
        window_dimensions_px = (800, 700)   #window_width_px, window_height_px   (600, 500)
    else:
        window_dimensions_px = (800, 700)   #window_width_px, window_height_px   (800, 700)
    

    # Create the first user/client and the methods for moving between the screen and the world.
    env = Environment(window_dimensions_px, 10.0) # 10m in along the x axis.

    game_window = GameWindow(window_dimensions_px, 'nothing yet...')

    # Define the Left, Right, Bottom, and Top boundaries of the game window.
    air_table = AirTable({"L_m":0.0, "R_m":game_window.UR_2d_m.x, "B_m":0.0, "T_m":game_window.UR_2d_m.y})

    #=====================================================================
    # Box2d setup (start)
    #=====================================================================
    
    # Create the world
    b2_world = b2World(gravity=(-0.0, -0.0), doSleep=True)
    
    # List of wall bodies.
    # Floor
    wall_body = b2_world.CreateStaticBody(position=(0.0, -1.0),
                   shapes=b2PolygonShape(box=(150, 1.0)) )
    air_table.b2_walls.append( wall_body)  
    
    # Ceiling
    wall_body = b2_world.CreateStaticBody(position=(0.0, game_window.UR_2d_m.y+1.0),
                   shapes=b2PolygonShape(box=(150, 1.0)) )
    air_table.b2_walls.append( wall_body)  
    
    # Left wall.
    wall_body = b2_world.CreateStaticBody(position=(-1.0, 0.0),
                   shapes=b2PolygonShape(box=(1.0, 150.0)) )
    air_table.b2_walls.append( wall_body)   
    
    # Right wall.
    wall_body = b2_world.CreateStaticBody(position=(game_window.UR_2d_m.x+1.0, 0.0),
                   shapes=b2PolygonShape(box=(1.0, 150.0)) )
    air_table.b2_walls.append( wall_body)   
    
    #=====================================================================
    # Box2d setup (end)
    #=====================================================================

    # Add some pucks to the table.
    demo_mode = 8
    make_some_pucks( demo_mode)

    # Setup network server.
    if platform.system() == 'Linux':
        local_ip = commands.getoutput("hostname -I")
    else:
        local_ip = socket.gethostbyname(socket.gethostname())
    print "Server IP address:", local_ip
    game_server = GameServer(localaddr=(local_ip, 4330))
    
    # Font object for rendering text onto display surface.
    fnt_FPS       = pygame.font.SysFont("Arial", 14)
    fnt_gameTimer = pygame.font.SysFont("Arial", 60)
    
    # Limit the framerate, but let it float below this limit.
    framerate_limit = 250
    b2d_timestep = 1.0/float(framerate_limit)
    dt_render_s = 0.0
    dt_render_limit_s = 1.0/float(120)     # = 1.0/render_framerate
    
    # An object containing the running average of the framerate of the physics calculations.
    if platform.system() == 'Linux':
        FR_avg = runningAvg(50) #50
    else:
        FR_avg = runningAvg(300) #500
    
    while True:
        dt_physics_s = float(myclock.tick( framerate_limit) * 1e-3)
        #dt_physics_s = 1/120.0
        #print dt_physics_s, myclock.get_fps()
        
        # You can optionally comment out the following line. This calculation of 
        # the Box2D timestep (based on the measured timestep) keeps the motion 
        # life-like even when hardware framerates drop below framerate_limit. If 
        # it is commented, the B2D timestep will be fixed (=1/framerate_limit), 
        # meaning the Box2D engine calculations will be accurate (and stable), but 
        # not presented in real time if the processor can't maintain that 
        # framerate (motion will appear slow).
        
        b2d_timestep = dt_physics_s
        
        if air_table.FPS_display:
            FR_avg.update(1/dt_physics_s)
        
        # Get input from local user.
        resetmode = env.get_local_user_input()
        
        # This check avoids problem when dragging the game window.
        if ((dt_physics_s < 0.10) and (not air_table.stop_physics)):
            
            # Reset the game based on local user control.
            if resetmode in [0,1,2,3,4,5,6,7,8,9]:
                demo_mode = resetmode
                print resetmode
                # This should remove all references to the pucks and effectively kill them off. If there were other
                # variables referring to this list, this would not stop the pucks.
                
                # Delete all the objects on the table. Cleaning out these list reference to these objects effectively
                # deletes the objects. Notice the controlled list must be cleared also.
                
                # First some Box2d clean-up.
                for eachpuck in air_table.pucks:
                    b2_world.DestroyBody(eachpuck.b2d_body)
                # Then all the lists.
                air_table.pucks = []
                air_table.puck_dictionary = {}
                air_table.controlled_pucks = []
                air_table.springs = []
                # This avoids call to the collision checker.
                air_table.collision_checking_enabled = False
                
                # Now just black out the screen.
                game_window.clear()
                
                # Reinitialize the demo.
                make_some_pucks( resetmode)               
                        
            if (dt_render_s > dt_render_limit_s):
                # Get input from network clients.
                game_server.Pump()
                env.checkForQuietClients()
                
            for client_name in env.clients:
                # Calculate client related forces.
                env.clients[client_name].calc_string_forces_on_pucks()
                
            if (dt_render_s > dt_render_limit_s):
                # Control the zoom
                env.control_zoom_and_view()
                
                for controlled_puck in air_table.controlled_pucks:
                    # Rotate based on keyboard of the controlling client.
                    controlled_puck.jet.client_rotation_control( controlled_puck.client_name)
                    controlled_puck.gun.client_rotation_control( controlled_puck.client_name)
                    
                    # Turn gun on/off
                    controlled_puck.gun.control_firing( controlled_puck.client_name)
                    
                    # Turn shield on/off
                    controlled_puck.gun.control_shield( controlled_puck.client_name)
                    
            
            # Calculate jet forces on pucks...
            for controlled_puck in air_table.controlled_pucks:
                controlled_puck.jet.turn_jet_forces_onoff( controlled_puck.client_name)
            
            # Calculate the forces the springs apply on the pucks...
            for eachspring in air_table.springs:
                eachspring.calc_spring_forces_on_pucks()
                
            # Apply forces to the pucks and calculate movements.
            for eachpuck in air_table.pucks:
                air_table.update_TotalForceVectorOnPuck( eachpuck, dt_physics_s)
            
            # Run Box2d    
            b2_world.Step(b2d_timestep, 10, 10)    
            
            # Get new positions, translational velocities, and rotational speeds, from box2d
            for eachpuck in air_table.pucks:
                eachpuck.get_Box2d_XandV()
            
            # Check for puck-puck collisions.
            if air_table.collision_checking_enabled:
                air_table.check_for_collisions()
            
            if (dt_render_s > dt_render_limit_s):
                
                # Erase the blackboard.
                if not air_table.g_ON:
                    game_window.surface.fill((0,0,0))  # Black
                else:
                    #grayscale = 50
                    #game_window.surface.fill((grayscale,grayscale,grayscale))  # Gray
                    game_window.surface.fill((0,82,110))  # Blue
                    
                # Display FPS and game timer text.
                if air_table.FPS_display:
                    display_number(FR_avg.result, fnt_FPS, mode='FPS')
                    #display_number(1/dt_physics_s, fnt_FPS, mode='FPS')
                if (demo_mode == 7):
                    display_number(env.game_time_s, fnt_gameTimer, mode='gameTimer')
                
                # Clean out old bullets.
                puck_list_copy = air_table.pucks[:]
                for thisPuck in puck_list_copy:
                    if (thisPuck.bullet) and ((env.time_s - thisPuck.birth_time_s) > thisPuck.age_limit_s):
                        # First remove the box2d bullet.
                        b2_world.DestroyBody(thisPuck.b2d_body)  #b2d
                        air_table.pucks.remove(thisPuck)
                        
                del puck_list_copy       
                
                # Draw pucks, springs, mouse tethers, and jets.
                
                # Draw boundaries of table.
                air_table.draw()
                
                for eachpuck in air_table.pucks: 
                    eachpuck.draw()
                    if (eachpuck.jet != None):
                        if env.clients[eachpuck.client_name].active or (eachpuck.client_name == 'test'):
                            eachpuck.jet.draw()
                            eachpuck.gun.draw()
                                            
                for eachspring in air_table.springs: 
                    eachspring.draw()
                
                env.remove_healthless_clients()
                
                for client_name in env.clients:
                    if (env.clients[client_name].selected_puck != None):
                        env.clients[client_name].draw_cursor_string()
                    
                    # Draw cursors for network clients.
                    if ((client_name != 'local') and env.clients[client_name].active):
                        env.clients[client_name].draw_fancy_server_cursor()
                    
                    #print client_name, env.clients[client_name].bullet_hit_count
                                        
                pygame.display.flip()
                dt_render_s = 0
            
            # Limit the rendering framerate to be below that of the physics calculations.
            dt_render_s += dt_physics_s
            
            # Keep track of time for deleting old bullets.
            env.time_s += dt_physics_s
            
            # Jello madness game timer
            if air_table.tangled:
                env.game_time_s += dt_physics_s
                
#============================================================
# Run the main program.  
#============================================================

if __name__ == "__main__":  
    main()