Slick Forums

package org.newdawn.slick.tests;

import org.lwjgl.opengl.GL11;
import org.newdawn.slick.AppGameContainer;
import org.newdawn.slick.BasicGame;
import org.newdawn.slick.Color;
import org.newdawn.slick.GameContainer;
import org.newdawn.slick.Graphics;
import org.newdawn.slick.Image;
import org.newdawn.slick.Input;
import org.newdawn.slick.SlickException;

/**
* A test to demonstrate alphamap light effects
*
* @author kalle hämäläinen aka pitbuller
*/
public class AlphaMapTest extends BasicGame {
   /** The alpha map being applied */
   private Image alphaMap;
   /** The texture to apply over the top */
   private Image sky;
   /** the horizontal coordinate */
   private float x;
   /** the vertical coordinate */
   private float y;
   /** boolean array for all the keys */
   private boolean keys[] = new boolean[256];

   private final static float speed = 0.2f;

   /**
    * Create a new tester for the clip plane based clipping
    */
   public AlphaMapTest() {
      super("AlphaMapLight Test");

   }

   /**
    * @see org.newdawn.slick.BasicGame#init(org.newdawn.slick.GameContainer)
    */
   public void init(GameContainer container) throws SlickException {
      alphaMap = new Image("testdata/alphamini.png");
      sky = new Image("testdata/sky.jpg");
   }

   /**
    * @see org.newdawn.slick.BasicGame#update(org.newdawn.slick.GameContainer,
    *      int)
    */
   public void update(GameContainer container, int delta)
         throws SlickException {
      if (keys[Input.KEY_UP])
         y -= speed * delta;
      if (keys[Input.KEY_DOWN])
         y += speed * delta;
      if (keys[Input.KEY_LEFT])
         x -= speed * delta;
      if (keys[Input.KEY_RIGHT])
         x += speed * delta;
      if (keys[Input.KEY_ESCAPE])
         container.exit();

   }

   /**
    * @see org.newdawn.slick.Game#render(org.newdawn.slick.GameContainer,
    *      org.newdawn.slick.Graphics)
    */
   public void render(GameContainer container, Graphics g)
         throws SlickException {
      /** first draw everything as normal */
      sky.draw();
      /** then add lights */
      lights(g, 4);

      /** then draw UI */
      g.setColor(Color.white);
      g.drawString("AlphaMapTest", 270, 10);
   }

   private final void lights(Graphics g, int size) {

      /** Scaling stuff so we don't have to use big alpha map image */
      float invSize = 1f / size;
      g.scale(size, size);

      /** setting alpha channel ready so lights add up instead of clipping */
      g.clearAlphaMap();
      GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE);

      /** actual lights, coordinates are transformed to scaled coordinates */
      alphaMap.drawCentered(x * invSize, y * invSize);
      alphaMap.drawCentered(200 * invSize, 200 * invSize);

      /** Scaling back stuff so we don't have to use big alpha map image */
      g.scale(invSize, invSize);

      /**
       * setting alpha channel for clearing everything but light maps just
       * added
       */
      GL11.glBlendFunc(GL11.GL_ONE, GL11.GL_DST_ALPHA);

      /** paint everything else with black */
      g.fillRect(0, 0, 400, 400);
      /** setting drawing mode back to normal */
      g.setDrawMode(Graphics.MODE_NORMAL);

   }

   /**
    * @see org.newdawn.slick.BasicGame#keyPressed(int, char)
    */
   public void keyPressed(int key, char c) {
      keys[key] = true;
   }

   public void keyReleased(int key, char c) {
      keys[key] = false;
   }

   /**
    * Entry point to our test
    *
    * @param argv
    *            The arguments to pass into the test
    */
   public static void main(String[] argv) {
      try {
         AppGameContainer container = new AppGameContainer(
               new AlphaMapTest());
         container.setDisplayMode(400, 400, false);
         container.start();
      } catch (SlickException e) {
         e.printStackTrace();
      }
   }
}

      /** paint everything else with black */
      g.setColor(Color.black);

GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE);
//lightmaps there
GL11.glBlendFunc(GL11.GL_ONE, GL11.GL_DST_ALPHA);
//black rect there