actor.java

J2ME Game Programming的隋书源代码

      return world;
   }

   /**
    * set spin rate in degrees per second
    * @param i 0-360 degrees
    */
   public final void setSpin(int i)
   {
      spinFP = MathFP.toFP(i);
   }

   /**
    * Set an angle this actors wants to face; the actor will start spinning
    * at its default spin rate towards the target angle - see cycle for
    * the actual spin code.
    */
   public final void setTargetDirection(int angle)
   {
      targetAngle = angle;
      autoSpinning = false;
   }

   public final void setThrust(int i)
   {
      thrustFP = MathFP.div(i, MathFP.toFP(3));
   }

   public final int getThrust()
   {
      return MathFP.toInt(thrustFP);
   }

   public final boolean isThrusting()
   {
      return MathFP.toInt(thrustFP) != 0;
   }

   public final int getX()
   {
      return x;
   }

   public final int getY()
   {
      return y;
   }

   public final void setX(int xArg)
   {
      xFP = MathFP.toFP(xArg);
      x = xArg;
   }

   public final void setY(int yArg)
   {
      yFP = MathFP.toFP(yArg);
      y = yArg;
   }

   public final int getCenterX()
   {
      return x + (getWidth() / 2);
   }

   public final int getCenterY()
   {
      return getY() + (getHeight() / 2);
   }

   public final boolean isCollidingWith(int px, int py)
   {
      if (px >= x && px <= (x + getWidth()) &&
              py >= y && py <= (y + getHeight()))
         return true;
      return false;
   }

   public final boolean isCollidingWith(int ax, int ay, int w, int h)
   {
      if (y + getHeight() < ay || y > ay + h ||
              x + getWidth() < ax || x > ax + w)
         return false;
      return true;
   }

   public final boolean isCollidingWith(Actor another)
   {
      return isCollidingWith(another.getX(), another.getY(), another.getWidth(),
                             another.getHeight());
   }

   public void suicide()
   {
   }

   private boolean teleported;

   /**
    * A cycle method that moves the Actor a distance relative to its current
    * speed (the value of the speed int) and the amount of time that has passed
    * since the last call to cycle (deltaMS). This code uses a fluff value in
    * order to remember values too small to handle (below the tick level).
    * @param deltaMS The number of milliseconds that have passed since the last
    * call to cycle.
    */
   public void cycle(long deltaMS)
   {
      int ticks = (int) (deltaMS + fluff) / 100;

      // remember the bit we missed
      fluff += (deltaMS - (ticks * 100));

      if (ticks > 0)
      {
         int ticksFP = MathFP.toFP(ticks);

         // move towards our target direction, if we have one
         if (targetAngle != 0)
         {
            if (!autoSpinning)
            {
               // start spin in the dir of the target angle
               setSpin(isClockwise(getDirection(), targetAngle) ? -maxSpinRate : maxSpinRate);
            }

            // and check if we've made it to the target direction
            if (getAlignedDirection(targetAngle) == getDirection())
            {
               setSpin(0);
               setTargetDirection(0);
               autoSpinning = false;
            }
         }

         // spin based on degrees per tick
         if (spinFP != 0)
            setDirection(getRealDirection() + MathFP.toInt(MathFP.mul(ticksFP, spinFP)));

         // move based on our speed in pixels per ticks
         if (thrustFP != 0)
         {
            //#ifdef debug
            if (alignedDir > 359) System.out.println("bad aligneddir=" + alignedDir);
            if (alignedDir < 0) System.out.println("bad aligneddir=" + alignedDir);
            //#endif
            xAccFP = MathFP.mul(thrustFP, lookupCosFP[alignedDir]);
            yAccFP = MathFP.mul(thrustFP, -lookupSinFP[alignedDir]);
            xVelFP = MathFP.add(xVelFP, xAccFP);
            yVelFP = MathFP.add(yVelFP, yAccFP);
         }

         //System.out.println("accX=" + MathFP.toString(xAccFP) + " accY=" + MathFP.toString(yAccFP) +
         //						 " velX=" + MathFP.toString(xVelFP) + " velY=" + MathFP.toString(yVelFP));

         // If you change this remember to change the setVel code
         if (xVelFP > maxVelFP)
            xVelFP = maxVelFP;
         else if (xVelFP < -maxVelFP) xVelFP = -maxVelFP;
         if (yVelFP > maxVelFP)
            yVelFP = maxVelFP;
         else if (yVelFP < -maxVelFP) yVelFP = -maxVelFP;

         lastXFP = xFP;
         lastYFP = yFP;

         // adjust X
         xFP = MathFP.add(xFP, MathFP.mul(xVelFP, ticksFP));
         x = MathFP.toInt(xFP);
         teleported = false;
         // now check if we collided with anything (we test X first)
         if (collidable)
         {
            if (world.checkCollision(this, x, y, getWidth(), getHeight()))
            {
               xVelFP = MathFP.mul(xVelFP, bounceVelFP);
               xFP = MathFP.add(lastXFP, xVelFP);
               x = MathFP.toInt(xFP);
            }
            if (lastYFP != yFP) teleported = true;
         }

         // adjust Y
         // we also handle a special case where the x collision may have
         // caused the ship to move (teleport, gateway). In this case our
         // lastYFP is invalid and we should abort the collision test.
         if (!teleported)
         {
            yFP = MathFP.add(yFP, MathFP.mul(yVelFP, ticksFP));
            y = MathFP.toInt(yFP);

            // now check if we collided with anything in Y movement
            if (collidable)
            {
               if (world.checkCollision(this, x, y, getWidth(), getHeight()))
               {
                  yVelFP = MathFP.mul(yVelFP, bounceVelFP);
                  yFP = MathFP.add(lastYFP, yVelFP);
                  y = MathFP.toInt(yFP);
               }
            }
         }
      }
   }

   public void onCollision(Actor another)
   {
   }


   /******************************* STATICS **********************************/

   /**
    * returns the shortest turning direction from one angle to another
    */
   public final static boolean isClockwise(int angleA, int angleB)
   {
      if (angleA > angleB)
         return (Math.abs(angleA - angleB)) < (angleB + (360 - angleA));
      else
         return (angleA + (360 - angleB)) < (Math.abs(angleB - angleA));
   }

   /**
    * Returns a game relative angle between two points
    */
   public final static int getFacingAngle(int x, int y, int ax, int ay)
   {
      // figure the two sides of our right angle triangle
      int a = MathFP.toFP(Math.abs(ax - x));
      int b = MathFP.toFP(Math.abs(ay - y));

      if (a == 0) a = FP_ONE;
      if (b == 0) b = FP_ONE;

      int bovera = MathFP.div(b, a);
      int angleInRadians = MathFP.atan(bovera);
      int angle = getAngleFromRadians(angleInRadians);

      // The tan result from this calculation is between 0 and 90 degrees so now
// we adjust the result for the actual quadrant we're in relative to the
// other Actor.
      if (ax < x) // left side
      {
         if (ay < y)
            return angle + 90;   // top
         return angle + 180;     // bottom
      }
      else // right side
      {
         if (ay < y)
            return angle;        // top
         return angle + 270;     // bottom
      }
   }

   public final static int getAngleFromRadians(int radiansFP)
   {
      return MathFP.toInt(MathFP.mul(radiansFP, FP_DEGREES_PER_RAD));
   }

   public final static int getRadiansFromAngle(int angle)
   {
      return MathFP.div(MathFP.toFP(angle), FP_DEGREES_PER_RAD);
   }

   /**
    * returns the opposite of an angle (ie. 0=180, 90=270)
    * @param angle
    */
   public final static int getOppositeAngle(int angle)
   {
      if (angle < 180) return angle + 180;
      return angle - 180;
   }

   /**
    * Project a point along a vector
    * @param x starting x position
    * @param y starting y position
    * @param angle angle to project along
    * @param distance distance to project
    * @return int[] containing x and y int positions
    */
   public final static int[] getProjectedPos(int x, int y, int angle,
                                             int distance)
   {
      int dx = lookupCosFP[angle];
      int dy = -lookupSinFP[angle];

      int xFP = MathFP.toFP(x);
      int yFP = MathFP.toFP(y);
      int distanceFP = MathFP.toFP(distance);

      xFP = MathFP.add(xFP, MathFP.mul(dx, distanceFP));
      yFP = MathFP.add(yFP, MathFP.mul(dy, distanceFP));

      int[] result = {MathFP.toInt(xFP), MathFP.toInt(yFP)};
      return result;
   }


   public final static int distance(int x1, int y1, int x2, int y2)
   {
      int dx = (x2 - x1) * (x2 - x1);
      int dy = (y2 - y1) * (y2 - y1);
      if (dx == 0 || dy == 0) return 0;

      try
      {
         return MathFP.toInt(MathFP.sqrt(MathFP.toFP(dx + dy)));
      }

      catch (ArithmeticException ae)
      {
         return 0;
      }
   }

}