1:  package

   2:  {

   3:      import flash.events.Event;

   4:      import flash.display.MovieClip;    

   5:   

   6:      public class Car extends MovieClip

   7:      {

   8:          // Internal properties

   9:          public var PositionX:Number = 300;

  10:          public var PositionY:Number = 200;

  11:          public var Speed:Number = 0;

  12:          public var Direction:int = 0; // 0 up, 90 right, 180 down, -90 left

  13:          public var TurningSpeed:Number = 0;

  14:          

  15:          public var HandBrakeOn:Boolean = false;

  16:          public var GasOn:Boolean = false;

  17:          public var BrakeOn:Boolean = false;

  18:          public var TurnLeft:Boolean = false;

  19:          public var TurnRight:Boolean = false;

  20:          

  21:          // Car characteristics

  22:          const BRAKE_FORCE:Number = .9; // Speed reduction per tick

  23:          const ACCERATION_FORCE:Number = .9; // Speed increase per tick

  24:          const TURNING_FORCE:Number = 4.5; // Turn amount per tick

  25:          

  26:          const FRICTION:Number = 1; // Slowdown per tick

  27:          

  28:          const MAX_SPEED:Number = 18; // Max car speed

  29:          const MAX_TURN_SPEED:Number = 10; // Max turning speed

  30:          

  31:          public function Car():void

  32:          {

  33:              trace("Car created" );

  34:              addEventListener( Event.ENTER_FRAME, enterFrame );

  35:          }

  36:          

  37:          // Tick

  38:          function enterFrame( ev:Event ):void

  39:          {

  40:              // Accelerator

  41:              if ( GasOn && Speed <= MAX_SPEED )

  42:                  Speed += ACCERATION_FORCE; // Gas on

  43:              else if ( !GasOn && Speed > 0 )

  44:                  Speed -= FRICTION; // Gas on, friction slow down

  45:                  

  46:              // Brake

  47:              if ( BrakeOn && Speed > 0 )

  48:                  Speed -= BRAKE_FORCE;

  49:   

  50:              // Make sure speed doesn't become a negative number (No revesing - yet)

  51:              if ( Speed < 0 )

  52:                  Speed = 0;                                

  53:          

  54:              // Turning

  55:              if ( TurnRight && TurningSpeed <= MAX_TURN_SPEED)

  56:              { // Right

  57:                  TurningSpeed += TURNING_FORCE;

  58:              }

  59:              else if ( TurnLeft && (TurningSpeed*-1) <= MAX_TURN_SPEED )

  60:              { // Left

  61:                  TurningSpeed -= TURNING_FORCE;

  62:              }

  63:              else

  64:              { // Reset steering

  65:              

  66:                  // If only a little out, reset completely

  67:                  if ( TurningSpeed < .5 && TurningSpeed > -.5 )

  68:                      TurningSpeed = 0;

  69:                  

  70:                  // Slowly reset

  71:                  if ( TurningSpeed > 0 )

  72:                      TurningSpeed -= TURNING_FORCE;

  73:                  else if ( TurningSpeed < 0 )

  74:                      TurningSpeed += TURNING_FORCE;

  75:              }

  76:              

  77:              // Change direction - but only if moving!

  78:              if ( Speed > 0 )

  79:              {

  80:                  Direction += TurningSpeed;

  81:                  if ( Direction > 360 )

  82:                      Direction = 0;

  83:                  else if ( Direction < 0 )

  84:                      Direction = 359;

  85:              }

  86:              

  87:              // Calculate position, based on speed and direction

  88:              // Thanks for Matt Wolf for re-explaining trig to me

  89:              var ChangeX:Number = Math.sin(DegToRad(Direction)) * Speed;

  90:              var ChangeY:Number = Math.cos(DegToRad(Direction)) * Speed;

  91:   

  92:              PositionX += ChangeX;

  93:              PositionY -= ChangeY;

  94:                                          

  95:              // trace( "Speed: " + Speed );

  96:              // trace( "Direction: " + Direction );            

  97:          }

  98:   

  99:          // Convert the 0-360 direction into the format Flash uses

 100:          public function DirectionFlash():int

 101:          {

 102:              if ( Direction <= 180 )

 103:                  return Direction;

 104:              else

 105:                  return Direction - 360;

 106:          }

 107:          

 108:          public function DegToRad( Degree:Number ):Number

 109:          {

 110:              return Degree * Math.PI / 180;

 111:          }

 112:      }

 113:   

 114:  }