WeldTest.java

package me.tomski.blobrun.desktop;


import com.badlogic.gdx.ApplicationListener;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.InputProcessor;
import com.badlogic.gdx.backends.lwjgl.LwjglApplication;
import com.badlogic.gdx.backends.lwjgl.LwjglApplicationConfiguration;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.math.Vector3;
import com.badlogic.gdx.physics.box2d.*;
import com.badlogic.gdx.physics.box2d.BodyDef.BodyType;
import com.badlogic.gdx.physics.box2d.joints.MouseJoint;
import com.badlogic.gdx.physics.box2d.joints.MouseJointDef;
import com.badlogic.gdx.physics.box2d.joints.WeldJointDef;
import com.badlogic.gdx.utils.Array;
import com.badlogic.gdx.utils.TimeUtils;

/**
 * Created by Tom on 15/04/14.
 */
public class WeldTest {

	public static void main(String[] args) {
		LwjglApplicationConfiguration config = new LwjglApplicationConfiguration();
		config.width = 1280;
		config.height = 720;
		config.foregroundFPS = 60;
		config.backgroundFPS = 60;
		config.fullscreen = false;
		config.vSyncEnabled = true;
		config.resizable = false;
		new LwjglApplication(new WeldTestDemo());
	}

	static class WeldTestDemo implements ApplicationListener, InputProcessor {

		World world;
		OrthographicCamera camera;
		Box2DDebugRenderer renderer;
		MouseJoint mouseJoint = null;
		Body hitBody = null;
		Body groundBody;

		long lastCreate = 0;
		Contact createContact = null;

		@Override
		public void create() {
			world = new World(new Vector2(0, -10), false);

			camera = new OrthographicCamera(40, 22.5f);
			camera.position.set(20, 11.25f, 0);
			camera.update();
			renderer = new Box2DDebugRenderer();

			Body bodyOne = createBody();
			Body bodyTwo = createBody();
			Body kin = createKinematicBody();

			bodyOne.setTransform(10, 10, 0);
			bodyTwo.setTransform(10, 13, 0);

			kin.setTransform(20,10,0);
			kin.setAngularVelocity(0.5f);

			WeldJointDef jointDef = new WeldJointDef();
			jointDef.initialize(bodyOne, bodyTwo, bodyTwo.getWorldCenter());
			jointDef.collideConnected = false;
			world.createJoint(jointDef);

			PolygonShape groundPoly = new PolygonShape();
			groundPoly.setAsBox(50, 1);

			BodyDef groundBodyDef = new BodyDef();
			groundBodyDef.type = BodyType.StaticBody;
			groundBodyDef.position.set(0, 0);
			groundBody = world.createBody(groundBodyDef);

			FixtureDef fixtureDef = new FixtureDef();
			fixtureDef.shape = groundPoly;
			fixtureDef.filter.groupIndex = 0;
			groundBody.createFixture(fixtureDef);
			groundPoly.dispose();

			Gdx.input.setInputProcessor(this);
		}

		private Body createBody() {
			BodyDef def = new BodyDef();
			def.type = BodyType.DynamicBody;

			PolygonShape shape = new PolygonShape();
			shape.setAsBox(1, 1);

			Body b = world.createBody(def);

			FixtureDef fDef = new FixtureDef();
			fDef.shape = shape;
			fDef.density = 0.2f;
			fDef.friction = 0.2f;
			fDef.restitution = 0.5f;

			b.createFixture(fDef);
			shape.dispose();

			return b;
		}

		private Body createKinematicBody() {
			BodyDef def = new BodyDef();
			def.type = BodyType.KinematicBody;

			PolygonShape shape = new PolygonShape();
			shape.setAsBox(3, 3);

			Body b = world.createBody(def);

			FixtureDef fDef = new FixtureDef();
			fDef.shape = shape;
			fDef.density = 15f;
			fDef.friction = 0.2f;
			fDef.restitution = 0.5f;

			Fixture f = b.createFixture(fDef);
			f.setUserData("k");

			shape.dispose();

			return b;
		}

		private void createFallingBody() {

			BodyDef def = new BodyDef();
			def.type = BodyType.DynamicBody;

			CircleShape shape = new CircleShape();
			shape.setRadius(1);

			Body b = world.createBody(def);

			FixtureDef fDef = new FixtureDef();
			fDef.shape = shape;
			fDef.density = 0.9f;
			fDef.friction = 0.2f;
			fDef.restitution = 0.5f;

			Fixture f = b.createFixture(fDef);
			f.setUserData("d");

			shape.setRadius( shape.getRadius() * 2.0f);
			fDef.shape = shape;
			fDef.density = 0.1f;
			//fDef.isSensor = false;

			Fixture outer = b.createFixture(fDef);
			outer.setUserData("o");

			shape.dispose();

			b.setTransform(20, 50, 0);

		}

		public void createWeldJointFromContact() {
			System.out.println("A: " + createContact.getFixtureA().getUserData() + " B: " + createContact.getFixtureB().getUserData());

			Array<Fixture> bFixtures = createContact.getFixtureB().getBody().getFixtureList();

			for (int iB = 0; iB < bFixtures.size; iB++) {
				System.out.println("\t" + iB + " name: " + bFixtures.get(iB).getUserData());
			}

			WeldJointDef jointDef = new WeldJointDef();
			jointDef.initialize(createContact.getFixtureA().getBody(), createContact.getFixtureB().getBody(), createContact.getFixtureB().getBody().getWorldCenter());
			jointDef.collideConnected = true;
			world.createJoint(jointDef);

			//nudgeFixtures.add(create)

			createContact = null;
		}

		@Override
		public void resize(int width, int height) {

		}

		@Override
		public void render() {
			Gdx.gl.glClearColor(0.05f, 0.05f, 0.05f, 1f);
			Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

			world.step(1 / 30f, 6, 2);
			renderer.render(world, camera.combined);

			if (TimeUtils.millis() - lastCreate > 1000) {
				createFallingBody();
				lastCreate = TimeUtils.millis();
			}

			if (createContact != null) {
				createWeldJointFromContact();
			}
		}

		@Override
		public void pause() {

		}

		@Override
		public void resume() {

		}

		@Override
		public void dispose() {

		}

		@Override
		public boolean keyDown(int keycode) {
			return false;
		}

		@Override
		public boolean keyUp(int keycode) {
			return false;
		}

		@Override
		public boolean keyTyped(char character) {
			return false;
		}


		Vector3 testPoint = new Vector3();
		QueryCallback callback = new QueryCallback() {
			@Override
			public boolean reportFixture(Fixture fixture) {
				if (fixture.getBody() == groundBody) return true;
				if (fixture.testPoint(testPoint.x, testPoint.y)) {
					hitBody = fixture.getBody();
					return false;
				} else
					return true;
			}
		};


		@Override
		public boolean touchDown(int x, int y, int pointer, int newParam) {
			testPoint.set(x, y, 0);
			camera.unproject(testPoint);

			hitBody = null;
			world.QueryAABB(callback, testPoint.x - 0.1f, testPoint.y - 0.1f, testPoint.x + 0.1f, testPoint.y + 0.1f);

			if (hitBody != null) {
				MouseJointDef def = new MouseJointDef();
				def.bodyA = groundBody;
				def.bodyB = hitBody;
				def.collideConnected = true;
				def.target.set(testPoint.x, testPoint.y);
				def.maxForce = 1000.0f * hitBody.getMass();

				mouseJoint = (MouseJoint) world.createJoint(def);
				hitBody.setAwake(true);
			}
			return false;
		}

		Vector2 target = new Vector2();

		@Override
		public boolean touchDragged(int x, int y, int pointer) {

			if (mouseJoint != null) {
				camera.unproject(testPoint.set(x, y, 0));
				mouseJoint.setTarget(target.set(testPoint.x, testPoint.y));
			}
			return false;
		}

		@Override
		public boolean touchUp(int x, int y, int pointer, int button) {
			if (mouseJoint != null) {
				world.destroyJoint(mouseJoint);
				mouseJoint = null;
			}
			return false;
		}


		@Override
		public boolean mouseMoved(int screenX, int screenY) {
			return false;
		}

		@Override
		public boolean scrolled(int amount) {
			return false;
		}

	}
}