RayCastTest.java

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 * Copyright (c) 2011, Daniel Murphy
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 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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package org.jbox2d.gwt.showcase.client.example;

import java.util.List;

import org.jbox2d.callbacks.RayCastCallback;
import org.jbox2d.collision.shapes.CircleShape;
import org.jbox2d.collision.shapes.PolygonShape;
import org.jbox2d.common.Color3f;
import org.jbox2d.common.MathUtils;
import org.jbox2d.common.Vec2;
import org.jbox2d.dynamics.Body;
import org.jbox2d.dynamics.BodyDef;
import org.jbox2d.dynamics.Fixture;
import org.jbox2d.dynamics.FixtureDef;
import org.jbox2d.gwt.showcase.client.framework.BaseExample;
import org.jbox2d.gwt.showcase.client.framework.ShowcaseSettings;

public class RayCastTest extends BaseExample {
	
	public static final int e_maxBodies = 256;
	
	enum Mode {
		e_closest, e_any, e_multiple
	};
	
	int m_bodyIndex;
	Body[] m_bodies;
	Integer[] m_userData;
	PolygonShape[] m_polygons;
	CircleShape m_circle;
	
	float m_angle;
	
	Mode m_mode;
	
	@Override
	public String getTestName() {
		return "Raycast";
	}
	
	@Override
	public void initTest() {
		m_bodies = new Body[e_maxBodies];
		m_userData = new Integer[e_maxBodies];
		m_polygons = new PolygonShape[4];
		{
			BodyDef bd = new BodyDef();
			Body ground = m_world.createBody(bd);
			
			PolygonShape shape = new PolygonShape();
			shape.setAsEdge(new Vec2(-40.0f, 0.0f), new Vec2(40.0f, 0.0f));
			ground.createFixture(shape, 0.0f);
		}
		
		{
			Vec2 vertices[] = new Vec2[3];
			vertices[0] = new Vec2(-0.5f, 0.0f);
			vertices[1] = new Vec2(0.5f, 0.0f);
			vertices[2] = new Vec2(0.0f, 1.5f);
			m_polygons[0] = new PolygonShape();
			m_polygons[0].set(vertices, 3);
		}
		
		{
			Vec2 vertices[] = new Vec2[3];
			vertices[0] = new Vec2(-0.1f, 0.0f);
			vertices[1] = new Vec2(0.1f, 0.0f);
			vertices[2] = new Vec2(0.0f, 1.5f);
			m_polygons[1] = new PolygonShape();
			m_polygons[1].set(vertices, 3);
		}
		
		{
			float w = 1.0f;
			float b = w / (2.0f + MathUtils.sqrt(2.0f));
			float s = MathUtils.sqrt(2.0f) * b;
			
			Vec2 vertices[] = new Vec2[8];
			vertices[0] = new Vec2(0.5f * s, 0.0f);
			vertices[1] = new Vec2(0.5f * w, b);
			vertices[2] = new Vec2(0.5f * w, b + s);
			vertices[3] = new Vec2(0.5f * s, w);
			vertices[4] = new Vec2(-0.5f * s, w);
			vertices[5] = new Vec2(-0.5f * w, b + s);
			vertices[6] = new Vec2(-0.5f * w, b);
			vertices[7] = new Vec2(-0.5f * s, 0.0f);
			
			m_polygons[2] = new PolygonShape();
			m_polygons[2].set(vertices, 8);
		}
		
		{
			m_polygons[3] = new PolygonShape();
			m_polygons[3].setAsBox(0.5f, 0.5f);
		}
		
		{
			m_circle = new CircleShape();
			m_circle.m_radius = 0.5f;
		}
		
		m_bodyIndex = 0;
		
		m_angle = 0.0f;
		
		m_mode = Mode.e_closest;
	}
	
	RayCastClosestCallback ccallback = new RayCastClosestCallback();
	RayCastAnyCallback acallback = new RayCastAnyCallback();
	RayCastMultipleCallback mcallback = new RayCastMultipleCallback();
	
	// pooling
	Vec2 point1 = new Vec2();
	Vec2 d = new Vec2();
	Vec2 pooledHead = new Vec2();
	Vec2 point2 = new Vec2();
	
	@Override
	public void render(ShowcaseSettings settings) {
    //TODO(pruggia): verify if any of this needs to go inside step()
		super.render(settings);
		
		addTextLine("Mode = " + m_mode);
		
		float L = 11.0f;
		point1.set(0.0f, 10.0f);
		d.set(L * MathUtils.cos(m_angle), L * MathUtils.sin(m_angle));
		point2.set(point1);
		point2.addLocal(d);
		
		if (m_mode == Mode.e_closest) {
			ccallback.init();
			m_world.raycast(ccallback, point1, point2);
			
			if (ccallback.m_hit) {
				m_debugDraw.drawPoint(ccallback.m_point, 5.0f, new Color3f(0.4f, 0.9f, 0.4f));
				m_debugDraw.drawSegment(point1, ccallback.m_point, new Color3f(0.8f, 0.8f, 0.8f));
				pooledHead.set(ccallback.m_normal);
				pooledHead.mulLocal(.5f).addLocal(ccallback.m_point);
				m_debugDraw.drawSegment(ccallback.m_point, pooledHead, new Color3f(0.9f, 0.9f, 0.4f));
			}
			else {
				m_debugDraw.drawSegment(point1, point2, new Color3f(0.8f, 0.8f, 0.8f));
			}
		}
		else if (m_mode == Mode.e_any) {
			acallback.init();
			m_world.raycast(acallback, point1, point2);
			
			if (acallback.m_hit) {
				m_debugDraw.drawPoint(acallback.m_point, 5.0f, new Color3f(0.4f, 0.9f, 0.4f));
				m_debugDraw.drawSegment(point1, acallback.m_point, new Color3f(0.8f, 0.8f, 0.8f));
				pooledHead.set(acallback.m_normal);
				pooledHead.mulLocal(.5f).addLocal(acallback.m_point);
				m_debugDraw.drawSegment(acallback.m_point, pooledHead, new Color3f(0.9f, 0.9f, 0.4f));
			}
			else {
				m_debugDraw.drawSegment(point1, point2, new Color3f(0.8f, 0.8f, 0.8f));
			}
		}
		else if (m_mode == Mode.e_multiple) {
			mcallback.init();
			m_world.raycast(mcallback, point1, point2);
			m_debugDraw.drawSegment(point1, point2, new Color3f(0.8f, 0.8f, 0.8f));
			
			for (int i = 0; i < mcallback.m_count; ++i) {
				Vec2 p = mcallback.m_points[i];
				Vec2 n = mcallback.m_normals[i];
				m_debugDraw.drawPoint(p, 5.0f, new Color3f(0.4f, 0.9f, 0.4f));
				m_debugDraw.drawSegment(point1, p, new Color3f(0.8f, 0.8f, 0.8f));
				pooledHead.set(n);
				pooledHead.mulLocal(.5f).addLocal(p);
				m_debugDraw.drawSegment(p, pooledHead, new Color3f(0.9f, 0.9f, 0.4f));
			}
		}
		
	  m_angle += 0.25f * MathUtils.PI / 180.0f;
	}
	
  @Override
  public List<String> getInstructions() {
    List<String> instructions = super.getInstructions();
    instructions.add("Press 1-5 to drop stuff, m to change the mode");
    instructions.add("Polygon 1 is filtered");
    return instructions;
  }
	
	void Create(int index) {
		if (m_bodies[m_bodyIndex] != null) {
			m_world.destroyBody(m_bodies[m_bodyIndex]);
			m_bodies[m_bodyIndex] = null;
		}
		
		BodyDef bd = new BodyDef();
		
		float x = (float) Math.random() * 20 - 10;
		float y = (float) Math.random() * 20;
		bd.position.set(x, y);
		bd.angle = (float) Math.random() * MathUtils.TWOPI - MathUtils.PI;
		
		m_userData[m_bodyIndex] = index;
		bd.userData = m_userData[m_bodyIndex];
		
		if (index == 4) {
			bd.angularDamping = 0.02f;
		}
		
		m_bodies[m_bodyIndex] = m_world.createBody(bd);
		
		if (index < 4) {
			FixtureDef fd = new FixtureDef();
			fd.shape = m_polygons[index];
			fd.friction = 0.3f;
			m_bodies[m_bodyIndex].createFixture(fd);
		}
		else {
			FixtureDef fd = new FixtureDef();
			fd.shape = m_circle;
			fd.friction = 0.3f;
			
			m_bodies[m_bodyIndex].createFixture(fd);
		}
		
		m_bodyIndex = (m_bodyIndex + 1) % e_maxBodies;
	}
	
	void DestroyBody() {
		for (int i = 0; i < e_maxBodies; ++i) {
			if (m_bodies[i] != null) {
				m_world.destroyBody(m_bodies[i]);
				m_bodies[i] = null;
				return;
			}
		}
	}
	
	@Override
	public void keyPressed(char argKeyChar, int argKeyCode, ShowcaseSettings settings) {
		
		switch (argKeyChar) {
			case '1' :
			case '2' :
			case '3' :
			case '4' :
			case '5' :
				Create(argKeyChar - '1');
				break;
			
			case 'd' :
				DestroyBody();
				break;
			
			case 'm' :
				if (m_mode == Mode.e_closest) {
					m_mode = Mode.e_any;
				}
				else if (m_mode == Mode.e_any) {
					m_mode = Mode.e_multiple;
				}
				else if (m_mode == Mode.e_multiple) {
					m_mode = Mode.e_closest;
				}
				break;
		}
	}
	
}

// This test demonstrates how to use the world ray-cast feature.
// NOTE: we are intentionally filtering one of the polygons, therefore
// the ray will always miss one type of polygon.

// This callback finds the closest hit. Polygon 0 is filtered.
class RayCastClosestCallback implements RayCastCallback {
	
	boolean m_hit;
	Vec2 m_point;
	Vec2 m_normal;
	
	public void init() {
		m_hit = false;
	}
	
	public float reportFixture(Fixture fixture, Vec2 point, Vec2 normal, float fraction) {
		Body body = fixture.getBody();
		Object userData = body.getUserData();
		if (userData != null) {
			int index = (Integer) userData;
			if (index == 0) {
				// filter
				return -1f;
			}
		}
		
		m_hit = true;
		m_point = point;
		m_normal = normal;
		return fraction;
	}
	
};

// This callback finds any hit. Polygon 0 is filtered.
class RayCastAnyCallback implements RayCastCallback {
	public void init() {
		m_hit = false;
	}
	
	public float reportFixture(Fixture fixture, Vec2 point, Vec2 normal, float fraction) {
		Body body = fixture.getBody();
		Object userData = body.getUserData();
		if (userData != null) {
			int index = (Integer) userData;
			if (index == 0) {
				// filter
				return -1f;
			}
		}
		
		m_hit = true;
		m_point = point;
		m_normal = normal;
		return 0f;
	}
	
	boolean m_hit;
	Vec2 m_point;
	Vec2 m_normal;
};

// This ray cast collects multiple hits along the ray. Polygon 0 is filtered.
class RayCastMultipleCallback implements RayCastCallback {
	public int e_maxCount = 5;
	Vec2 m_points[] = new Vec2[e_maxCount];
	Vec2 m_normals[] = new Vec2[e_maxCount];
	int m_count;
	
	public void init() {
		for (int i = 0; i < e_maxCount; i++) {
			m_points[i] = new Vec2();
			m_normals[i] = new Vec2();
		}
		m_count = 0;
	}
	
	public float reportFixture(Fixture fixture, Vec2 point, Vec2 normal, float fraction) {
		Body body = fixture.getBody();
		int index = 0;
		Object userData = body.getUserData();
		if (userData != null) {
			index = (Integer) userData;
			if (index == 0) {
				// filter
				return -1f;
			}
		}
		
		assert (m_count < e_maxCount);
		
		m_points[m_count].set(point);
		m_normals[m_count].set(normal);
		++m_count;
		
		if (m_count == e_maxCount) {
			return 0f;
		}
		
		return 1f;
	}
	
};