package com.leakedbits.codelabs.box2d;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.physics.box2d.Body;
import com.badlogic.gdx.physics.box2d.BodyDef.BodyType;
import com.badlogic.gdx.physics.box2d.Box2DDebugRenderer;
import com.badlogic.gdx.physics.box2d.Contact;
import com.badlogic.gdx.physics.box2d.ContactImpulse;
import com.badlogic.gdx.physics.box2d.ContactListener;
import com.badlogic.gdx.physics.box2d.Fixture;
import com.badlogic.gdx.physics.box2d.FixtureDef;
import com.badlogic.gdx.physics.box2d.Manifold;
import com.badlogic.gdx.physics.box2d.Shape;
import com.badlogic.gdx.physics.box2d.World;
import com.leakedbits.codelabs.box2d.utils.Box2DFactory;
import com.leakedbits.codelabs.utils.Sample;
public class CollisionsSample extends Sample implements ContactListener {
/* Use Box2DDebugRenderer, which is a model renderer for debug purposes */
private Box2DDebugRenderer debugRenderer;
/* As always, we need a camera to be able to see the objects */
private OrthographicCamera camera;
/* Define a world to hold all bodies and simulate reactions between them */
private World world;
private Body walls;
private boolean ballTouchedWall;
private boolean ballTouchedBox;
/* Fields to store previous accelerometer values in each iteration */
private float prevAccelX;
private float prevAccelY;
/**
* Main constructor used to update sample name.
*/
public CollisionsSample() {
name = "Collisions";
}
@Override
public void render(float delta) {
/*
* Clear screen with a black background. Use red instead if the ball
* touched a wall or blue if touched the box.
*/
if (ballTouchedWall) {
Gdx.gl.glClearColor(0.6f, 0, 0, 1);
} else if (ballTouchedBox) {
Gdx.gl.glClearColor(0, 0, 0.6f, 1);
} else {
Gdx.gl.glClearColor(0, 0, 0, 1);
}
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
/* Check if we should change the gravity */
processAccelerometer();
/* Render all graphics before do physics step */
debugRenderer.render(world, camera.combined);
/* Step the simulation with a fixed time step of 1/60 of a second */
world.step(1 / 60f, 6, 2);
}
@Override
public void show() {
/*
* This line is found in every sample but is not necessary for the
* sample functionality. calls Sample.show() method. That method set the
* sample to receive all touch and key input events. Also prevents the
* app from be closed whenever the user press back button and instead
* returns to main menu.
*/
super.show();
/*
* Create world with a common gravity vector (9.81 m/s2 downwards force)
* and tell world that we want objects to sleep. This last value
* conserves CPU usage. As we use the accelerometer and the world
* gravity to change bodies positions, we can't let bodies to sleep.
*/
world = new World(new Vector2(0, -9.81f), false);
/* Create renderer */
debugRenderer = new Box2DDebugRenderer();
/*
* Define camera viewport. Box2D uses meters internally so the camera
* must be defined also in meters. We set a desired width and adjust
* height to different resolutions.
*/
camera = new OrthographicCamera(20,
20 * (Gdx.graphics.getHeight() / (float) Gdx.graphics
.getWidth()));
/* Create the ball */
Shape shape = Box2DFactory.createCircleShape(1);
FixtureDef fixtureDef = Box2DFactory.createFixture(shape, 2.5f, 0.25f,
0.75f, false);
Box2DFactory.createBody(world, BodyType.DynamicBody, fixtureDef,
new Vector2(5, 0));
/* Create the box */
shape = Box2DFactory.createBoxShape(0.5f, 0.5f, new Vector2(0, 0), 0);
fixtureDef = Box2DFactory.createFixture(shape, 1, 0.5f, 0.5f, false);
Box2DFactory.createBody(world, BodyType.StaticBody, fixtureDef,
new Vector2(0, 0));
/* Create the walls */
walls = Box2DFactory.createWalls(world, camera.viewportWidth,
camera.viewportHeight, 1);
world.setContactListener(this);
}
@Override
public void dispose() {
debugRenderer.dispose();
world.dispose();
}
private void processAccelerometer() {
/* Get accelerometer values */
float y = Gdx.input.getAccelerometerY();
float x = Gdx.input.getAccelerometerX();
/*
* If accelerometer values have changed since previous processing,
* change world gravity.
*/
if (prevAccelX != x || prevAccelY != y) {
/* Negative on the x axis but not in the y */
world.setGravity(new Vector2(y, -x));
/* Store new accelerometer values */
prevAccelX = x;
prevAccelY = y;
}
}
@Override
public void beginContact(Contact contact) {
Fixture fixtureA = contact.getFixtureA();
Fixture fixtureB = contact.getFixtureB();
/*
* If one of the fixture contacting is an static body, and is the wall,
* set ballTouchedWall to true.
*/
if (fixtureA.getBody().getType() == BodyType.StaticBody) {
if (fixtureA.getBody().equals(walls)) {
ballTouchedBox = false;
ballTouchedWall = true;
} else {
ballTouchedBox = true;
ballTouchedWall = false;
}
} else if (fixtureB.getBody().getType() == BodyType.StaticBody) {
if (fixtureA.getBody().equals(walls)) {
ballTouchedBox = false;
ballTouchedWall = true;
} else {
ballTouchedBox = true;
ballTouchedWall = false;
}
}
}
@Override
public void endContact(Contact contact) {
}
@Override
public void preSolve(Contact contact, Manifold oldManifold) {
}
@Override
public void postSolve(Contact contact, ContactImpulse impulse) {
}
}
