actor.java

此文件是关于手机游戏开发的理论

/**
 * A dynamic moving object capable of existing in a World.
 */

import javax.microedition.lcdui.Graphics;

import net.jscience.math.kvm.MathFP;

abstract public class Actor
{
   public static final int FP_MINUS_1 = MathFP.toFP("-1.0");
   public static final int FP_MINUS_05 = MathFP.toFP("-0.5");
   public static final int FP_MINUS_01 = MathFP.toFP("-0.1");
   public static final int FP_225 = MathFP.toFP("22.5");
   public static final int FP_PI2 = MathFP.mul(MathFP.PI, MathFP.toFP(2));
   public static final int FP_DEGREES_PER_RAD = MathFP.div(MathFP.toFP(360), FP_PI2);
   public static final int FP_ONE = MathFP.toFP("1");

   // Actor types - we place them all in here so we can check the type of
   // a actor instance without doing an expensive instanceof test. This is
   // (of course) a horrible corruption of the intent of an abstract Actor
   // class - it's considered worth it for the performance gain.

   private int xFP, yFP;              	// current position
   private int x, y;							// integer versions (stored for speed)
   private int startingX, startingY;	// where the actor starts (used for restart)
   private int startingDir;				// starting direction (used for restart)
   private int lastXFP, lastYFP;
   private int lastX, lastY;
   private int xVelFP, yVelFP;        	// current velocity
   private int xAccFP, yAccFP;        	// current acceleration
   private int thrustFP;
   private int spinFP;                	// current spin rate (in degrees per second)
   private int maxSpinRate;           	// current spin rate (in degrees per second)
   private int maxVelFP;					// maximum velocity
   private int bounceVel;					// velocity to variance when bouncing off an impact
   private int realDir;                // actual direction in degrees
   private int alignedDir;             // aligned direction
   private int alignedDivDegreesFP;   	// degrees per facing division
   private boolean wantAlignment;		// turn auto alignment on

   private Actor nextInZMap;           // used by zmap to ref next actor
   private Actor prevInZMap;           // used by zmap to ref prev actor

   private long fluff = 0;
   private boolean autoSpinning;			// we set a flag to avoid over calling setSpin()
   private int targetAngle;

   protected Actor owner;
   protected World world;
   private boolean collidable;			// can anything collide with us?
   private boolean visible;				// whether we should be drawn or not

   public Actor()
   {
   }

   public Actor(World w)
   {
      world = w;
   }

   public void init(Actor newOwner, int xArg, int yArg, int thrustArg, int speedArg, int maxVelArg,
                    int dirArg, int alignedDivArg, int bounceVelArg, int maxSpinRateArg)
   {
      setX(xArg);
      setY(yArg);

      owner = newOwner;
      startingX = x;
      startingY = y;
      startingDir = dirArg;

      maxVelFP = MathFP.toFP(maxVelArg);
      maxSpinRate = maxSpinRateArg;

      wantAlignment = false;
      if (alignedDivArg > 0)
      {
         alignedDivDegreesFP = MathFP.div(360, alignedDivArg);
         wantAlignment = true;
      }
      setDirection(dirArg);
      setThrust(thrustArg);
      setVel(speedArg);

      bounceVel = bounceVelArg;
      collidable = true;
      visible = true;
   }

   public void setNextInZMap(Actor a) { nextInZMap = a; }
   public Actor getNextInZMap() { return nextInZMap; }
   public void setPrevInZMap(Actor a) { prevInZMap = a; }
   public Actor getPrevInZMap() { return prevInZMap; }


   // typically used to restart state for a level (ie. when the player dies)
   public void reset()
   {
      int oldX = x;
      int oldY = y;
      setX(startingX);
      setY(startingY);
      setDirection(startingDir);
      setSpin(0);
   }

   public int getStartingY()
   {
      return startingY;
   }

   public int getStartingX()
   {
      return startingX;
   }

   public final void setStartingPos(int startingX, int startingY)
   {
      this.startingX = startingX;
      this.startingY = startingY;
   }

   public final Actor getOwner()
   {
      return owner;
   }

   public final void setCollidable(boolean b)
   {
      collidable = b;
   }

   public final boolean isCollidable()
   {
      return collidable;
   }

   public final boolean isVisible()
   {
      return visible;
   }

   public final void setVisible(boolean visible)
   {
      this.visible = visible;
   }

   public void render(Graphics g, int offsetX, int offsetY)
   {
   }

   abstract public int getWidth();

   abstract public int getHeight();

   public final void setVel(int speedArg)
   {
      xVelFP = MathFP.mul(MathFP.toFP(speedArg), World.lookupCosFP[alignedDir]);
      yVelFP = MathFP.mul(MathFP.toFP(speedArg), -World.lookupSinFP[alignedDir]);
      // If you change this remember to change the cycle code
      if (xVelFP > maxVelFP)
         xVelFP = maxVelFP;
      else if (xVelFP < -maxVelFP) xVelFP = -maxVelFP;
      if (yVelFP > maxVelFP)
         yVelFP = maxVelFP;
      else if (yVelFP < -maxVelFP) yVelFP = -maxVelFP;
   }

   /**
    * Set the direction (in degrees; east = 0). We also set the alignedDir
    * to the closest angle available.
    */
   public final void setDirection(int d)
   {
      realDir = d;
      if (realDir < 0) realDir = (359 + (realDir));   // add the neg value
      if (realDir > 359) realDir = (d - 360);

      // set the facing direction to be the closest alignment
      if (wantAlignment)
      {
         alignedDir = getAlignedDirection(realDir);
      }
      else
         alignedDir = realDir;

   }

   public final int getAlignedDirection(int dir)
   {
      int fp = MathFP.toInt(MathFP.div(MathFP.toFP(dir), alignedDivDegreesFP));
      int ad = MathFP.toInt(MathFP.mul(MathFP.toFP(fp), alignedDivDegreesFP));
      if (ad < 0) ad = 0;
      if (ad > 359) ad = 0;
      return ad;
   }

   public final int getDirection()
   {
      return alignedDir;
   }

   public final int getRealDirection()
   {
      return realDir;
   }

   public final World getWorld()
   {
      return world;
   }

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

   public final void setTargetDirection(int angle)
   {
      // 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
      targetAngle = angle;
      autoSpinning = false;
   }

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

   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)));
         // figure out the amount of movement based on our speed in pixels per ticks
         if (thrustFP != 0)
         {
            //xAccFP = MathFP.mul(thrustFP, lookupCosFP[alignedDir]);
            //yAccFP = MathFP.mul(thrustFP, lookupSinFP[alignedDir]);
            //xVelFP = MathFP.add(xVelFP, xAccFP);
            //yVelFP = MathFP.add(yVelFP, yAccFP);
            xVelFP = MathFP.mul(thrustFP, World.lookupCosFP[alignedDir]);
            yVelFP = MathFP.mul(thrustFP, -World.lookupSinFP[alignedDir]);
         }

         // 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;
         lastX = x;
         lastYFP = yFP;
         lastY = y;

         // adjust X
         xFP = MathFP.add(xFP, MathFP.mul(xVelFP, ticksFP));
         x = MathFP.toInt(xFP);

         // now check if we collided with anything (we test X first)
         if (collidable)
         {
            // collisions are disabled in the raycaster
         }

         // 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 (lastYFP == yFP)
         {
            yFP = MathFP.add(yFP, MathFP.mul(yVelFP, ticksFP));
            y = MathFP.toInt(yFP);

            // now check if we collided with anything in Y movement
            if (collidable)
            {
               // collisions are disabled in the raycaster
            }
         }

      }
   }

   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));
   }

   public final static int getFacingAngle(int x1, int y1, int x2, int y2)
   {
      // figure the two sides of our right angle triangle
      int a = MathFP.toFP(Math.abs(x2 - x1));
      int b = MathFP.toFP(Math.abs(y2 - y1));

      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);

      // now adjust for which quadrant we're really in
      if (x2 < x1)
      {
         // left side
         if (y2 < y1)
            return angle + 180;
         return angle + 90;
      }
      else
      {
         // right side
         if (y2 < y1)
            return angle + 180;
         return angle;
      }
   }

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

   public final static int getRadiansFPFromAngle(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 = World.lookupCosFP[angle];
      int dy = World.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));

      //System.out.println("origX=" + x + " y=" + y + " dx=" + MathFP.toString(dx) + " dy=" + MathFP.toString(dy) + " " +
      //                   "distance=" + MathFP.toString(distanceFP) +
      //                   " x=" + MathFP.toString(xFP) + " y=" + MathFP.toString(yFP) + " rad=" +
      //                   MathFP.toString(radAngleFP));

      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;
      }
   }

}