Experimental pseudo-3d support for PointLight

Experimental feature (libgdx#40)
Only PolygonShapes currently drop dynamic shadow

src/box2dLight/Light.java

@@ -7,6 +7,7 @@
 import com.badlogic.gdx.physics.box2d.Filter;
 import com.badlogic.gdx.physics.box2d.Fixture;
 import com.badlogic.gdx.physics.box2d.RayCastCallback;
+import com.badlogic.gdx.utils.Array;
 import com.badlogic.gdx.utils.Disposable;
 
 /**
@@ -47,6 +48,7 @@ public abstract class Light implements Disposable {
 
 	protected Mesh lightMesh;
 	protected Mesh softShadowMesh;
+	protected Array<Mesh> dynamicShadowMeshes = new Array<Mesh>();
 
 	protected float segments[];
 	protected float[] mx;
@@ -90,6 +92,13 @@ public Light(RayHandler rayHandler, int rays, Color color,
 	 */
 	abstract void render();
 
+	/**
+	 * Render this light shadow
+	 */
+	void dynamicShadowRender() {
+
+	}
+
 	/**
 	 * Sets light distance
 	 * 
@@ -223,6 +232,10 @@ public void remove() {
 	public void dispose() {
 		lightMesh.dispose();
 		softShadowMesh.dispose();
+		for (Mesh mesh : dynamicShadowMeshes) {
+			mesh.dispose();
+		}
+		dynamicShadowMeshes.clear();
 	}
 
 	/**
@@ -444,5 +457,13 @@ static public void setContactFilter(short categoryBits, short groupIndex,
 		filterA.groupIndex = groupIndex;
 		filterA.maskBits = maskBits;
 	}
+
+	/** Returns the distance between the given line and point. Note the specified line is not a line segment. */
+	public static float sqDistanceLinePoint (float startX, float startY, float endX, float endY, float pointX, float pointY) {
+		float tmp1 = (endX - startX);
+		float tmp2 = (endY - startY);
+		float normalLength2 = tmp1 * tmp1 + tmp2 * tmp2;
+		return ((pointX - startX) * tmp2 - (pointY - startY) * tmp1) / normalLength2;
+	}
 
 }

src/box2dLight/LightData.java

@@ -0,0 +1,13 @@
+package box2dLight;
+
+public class LightData {
+
+	float height;
+
+	int shadowsDropped = 0;
+
+	public LightData(float h) {
+		height = h;
+	}
+
+}

src/box2dLight/PointLight.java

@@ -1,7 +1,15 @@
 package box2dLight;
 
 import com.badlogic.gdx.graphics.Color;
+import com.badlogic.gdx.graphics.GL20;
+import com.badlogic.gdx.graphics.Mesh;
+import com.badlogic.gdx.graphics.Mesh.VertexDataType;
+import com.badlogic.gdx.graphics.VertexAttribute;
+import com.badlogic.gdx.graphics.VertexAttributes.Usage;
 import com.badlogic.gdx.math.MathUtils;
+import com.badlogic.gdx.physics.box2d.Fixture;
+import com.badlogic.gdx.physics.box2d.PolygonShape;
+import com.badlogic.gdx.physics.box2d.Shape;
 
 /**
  * Light shaped as a circle with given radius
@@ -58,6 +66,74 @@ public void update () {
 
 		dirty = false;
 		updateMesh();
+
+		if (rayHandler.pseudo3d && height != 0f) {
+			prepeareFixtureData();
+		}
+	}
+
+	@Override
+	void dynamicShadowRender () {
+		if (height == 0f) return;
+
+		updateDynamicShadowMeshes();
+		for (Mesh m : dynamicShadowMeshes) {
+			m.render(rayHandler.lightShader, GL20.GL_TRIANGLE_STRIP);
+		}
+	}
+
+
+	protected void updateDynamicShadowMeshes() {
+		for (Mesh mesh : dynamicShadowMeshes) {
+			mesh.dispose();
+		}
+		dynamicShadowMeshes.clear();
+
+		if (dynamicSegments == null) {
+			dynamicSegments = new float[vertexNum * 16];
+		}
+
+		float colBits = rayHandler.ambientLight.toFloatBits();
+		for (Fixture fixture : affectedFixtures) {
+			LightData data = (LightData)fixture.getUserData();
+			Shape fixtureShape = fixture.getShape();
+			if (fixtureShape instanceof PolygonShape) {
+				Mesh mesh = new Mesh(
+						VertexDataType.VertexArray, staticLight, 2 * vertexNum, 0,
+						new VertexAttribute(Usage.Position, 2, "vertex_positions"),
+						new VertexAttribute(Usage.ColorPacked, 4, "quad_colors"),
+						new VertexAttribute(Usage.Generic, 1, "s"));
+				PolygonShape shape = (PolygonShape)fixtureShape;
+				int size = 0;
+				float l;
+				float dst = fixture.getBody().getWorldCenter().dst(start);
+				float f = 1f / data.shadowsDropped;
+				for (int n = 0; n < shape.getVertexCount(); n++) {
+					shape.getVertex(n, tmpVec);
+					tmpVec.set(fixture.getBody().getWorldPoint(tmpVec));
+
+					dynamicSegments[size++] = tmpVec.x;
+					dynamicSegments[size++] = tmpVec.y;
+					dynamicSegments[size++] = colBits;
+					dynamicSegments[size++] = f;
+
+					if (height > data.height) {
+						l = dst * data.height / (height - data.height);
+						if (l > distance - dst) l = distance - dst;
+					} else {
+						l = distance - dst;
+					}
+
+					tmpEnd.set(tmpVec).sub(start).limit(l).add(tmpVec);
+					dynamicSegments[size++] = tmpEnd.x;
+					dynamicSegments[size++] = tmpEnd.y;
+					dynamicSegments[size++] = colBits;
+					dynamicSegments[size++] = f;
+				}
+				mesh.setVertices(dynamicSegments, 0, size);
+				dynamicShadowMeshes.add(mesh);
+			}
+		}
 	}
 
 	/**
@@ -73,6 +149,10 @@ public void setDistance(float dist) {
 		dirty = true;
 	}
 
+	public void setHeight(float height) {
+		this.height = height;
+	}
+
 	/** Updates light basing on it's distance and rayNum **/
 	void setEndPoints() {
 		float angleNum = 360f / (rayNum - 1);

src/box2dLight/PositionalLight.java

@@ -10,6 +10,9 @@
 import com.badlogic.gdx.math.MathUtils;
 import com.badlogic.gdx.math.Vector2;
 import com.badlogic.gdx.physics.box2d.Body;
+import com.badlogic.gdx.physics.box2d.Fixture;
+import com.badlogic.gdx.physics.box2d.QueryCallback;
+import com.badlogic.gdx.utils.Array;
 
 /**
  * Abstract base class for all positional lights
@@ -20,6 +23,7 @@
  */
 public abstract class PositionalLight extends Light {
 
+	protected final Vector2 tmpStart = new Vector2();
 	protected final Vector2 tmpEnd = new Vector2();
 	protected final Vector2 start = new Vector2();
 
@@ -34,6 +38,12 @@ public abstract class PositionalLight extends Light {
 	protected float endX[];
 	protected float endY[];
 
+	protected float[] dynamicSegments;
+	final Vector2 tmpVec = new Vector2();
+	final Array<Fixture> affectedFixtures = new Array<Fixture>();
+
+	protected float height = 0f;
+
 	/** 
 	 * Creates new positional light and automatically adds it to the specified
 	 * {@link RayHandler} instance.
@@ -76,6 +86,7 @@ void update() {
 		if (staticLight && !dirty) return;
 
 		dirty = false;
+
 		updateMesh();
 	}
 
@@ -87,7 +98,7 @@ void render() {
 		lightMesh.render(
 			rayHandler.lightShader, GL20.GL_TRIANGLE_FAN, 0, vertexNum);
 
-		if (soft && !xray) {
+		if (soft && !xray && !rayHandler.pseudo3d) {
 			softShadowMesh.render(
 				rayHandler.lightShader,
 				GL20.GL_TRIANGLE_STRIP,
@@ -208,6 +219,10 @@ protected void setRayNum(int rays) {
 		cos = new float[rays];
 		endX = new float[rays];
 		endY = new float[rays];
+
+		if (rayHandler.pseudo3d) {
+			dynamicSegments = new float[vertexNum * 16];
+		}
 	}
 
 	protected boolean cull() {
@@ -238,12 +253,26 @@ protected void updateMesh() {
 			mx[i] = tmpEnd.x;
 			tmpEnd.y = endY[i] + start.y;
 			my[i] = tmpEnd.y;
-			if (rayHandler.world != null && !xray) {
+			if (rayHandler.world != null && !xray && !rayHandler.pseudo3d) {
 				rayHandler.world.rayCast(ray, start, tmpEnd);
 			}
 		}
 		setMesh();
 	}
+
+	protected void prepeareFixtureData() {
+		affectedFixtures.clear();
+		rayHandler.world.QueryAABB(
+				dynamicShadowCallback,
+				start.x - distance, start.y - distance,
+				start.x + distance, start.y + distance);
+		for (Fixture fixture : affectedFixtures) {
+			if (fixture.getUserData() instanceof LightData) {
+				LightData data = (LightData)fixture.getUserData();
+				data.shadowsDropped++;
+			}
+		}
+	}
 
 	protected void setMesh() {
 		// ray starting point
@@ -262,7 +291,7 @@ protected void setMesh() {
 		}
 		lightMesh.setVertices(segments, 0, size);
 
-		if (!soft || xray) return;
+		if (!soft || xray || rayHandler.pseudo3d) return;
 
 		size = 0;
 		// rays ending points.
@@ -280,4 +309,16 @@ protected void setMesh() {
 		softShadowMesh.setVertices(segments, 0, size);
 	}
 
+	final QueryCallback dynamicShadowCallback = new QueryCallback() {
+
+		@Override
+		public boolean reportFixture(Fixture fixture) {
+			if (fixture.getBody() != body) {
+				affectedFixtures.add(fixture);
+			}
+			return true;
+		}
+
+	};
+
 }

src/box2dLight/RayHandler.java

@@ -11,6 +11,8 @@
 import com.badlogic.gdx.graphics.glutils.ShaderProgram;
 import com.badlogic.gdx.math.MathUtils;
 import com.badlogic.gdx.math.Matrix4;
+import com.badlogic.gdx.physics.box2d.Body;
+import com.badlogic.gdx.physics.box2d.Fixture;
 import com.badlogic.gdx.physics.box2d.World;
 import com.badlogic.gdx.utils.Array;
 import com.badlogic.gdx.utils.Disposable;
@@ -72,6 +74,8 @@ public class RayHandler implements Disposable {
 	 * <p>NOTE: DO NOT MODIFY THIS LIST
 	 */
 	final Array<Light> disabledLights = new Array<Light>(false, 16);
+
+	final Array<Body> bodies = new Array<Body>();
 
 	final LightMap lightMap;
 	final ShaderProgram lightShader;
@@ -80,6 +84,9 @@ public class RayHandler implements Disposable {
 	boolean shadows = true;
 	boolean blur = true;
 
+	/** Experimental mode **/
+	boolean pseudo3d = false;
+
 	int blurNum = 1;
 
 	boolean customViewport = false;
@@ -271,6 +278,16 @@ public void updateAndRender() {
 	 * @see #render()
 	 */
 	public void update() {
+		world.getBodies(bodies);
+		for (Body body : bodies) {
+			for (Fixture fixture : body.getFixtureList()) {
+				if (fixture.getUserData() instanceof LightData) {
+					LightData data = (LightData)fixture.getUserData();
+					data.shadowsDropped = 0;
+				}
+			}
+		}
+
 		for (Light light : lightList) {
 			light.update();
 		}
@@ -297,7 +314,6 @@ public void render() {
 
 		Gdx.gl.glDepthMask(false);
 		Gdx.gl.glEnable(GL20.GL_BLEND);
-		simpleBlendFunc.apply();
 
 		boolean useLightMap = (shadows || blur); 
 		if (useLightMap) {
@@ -309,9 +325,18 @@ public void render() {
 		lightShader.begin();
 		{
 			lightShader.setUniformMatrix("u_projTrans", combined);
+
+			simpleBlendFunc.apply();
 			for (Light light : lightList) {
 				light.render();
 			}
+
+			if (pseudo3d) {
+				shadowBlendFunc.apply();
+				for (Light light : lightList) {
+					light.dynamicShadowRender();
+				}
+			}
 		}
 		lightShader.end();
 
@@ -535,6 +560,15 @@ public void useCustomViewport(int x, int y, int width, int height) {
 	public void useDefaultViewport() {
 		customViewport = false;
 	}
+
+	/** 
+	 * /!\ Experimental mode with dynamic shadowing in pseudo-3d world
+	 * 
+	 * @param flag
+	 */
+	public void setPseudo3dLight(boolean flag) {
+		pseudo3d = flag;
+	}
 
 	/**
 	 * Enables/disables lightMap automatic rendering.