Java tutorial
/******************************************************************************* * Copyright 2011 See AUTHORS file. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. ******************************************************************************/ /* * Copyright 2010 Mario Zechner (contact@badlogicgames.com), Nathan Sweet (admin@esotericsoftware.com) * * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the * License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" * BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language * governing permissions and limitations under the License. */ package com.badlogic.gdx.tests.box2d; import com.badlogic.gdx.Input.Keys; import com.badlogic.gdx.math.Vector2; import com.badlogic.gdx.physics.box2d.Body; import com.badlogic.gdx.physics.box2d.BodyDef; import com.badlogic.gdx.physics.box2d.BodyDef.BodyType; import com.badlogic.gdx.physics.box2d.EdgeShape; import com.badlogic.gdx.physics.box2d.FixtureDef; import com.badlogic.gdx.physics.box2d.PolygonShape; import com.badlogic.gdx.physics.box2d.Transform; import com.badlogic.gdx.physics.box2d.World; import com.badlogic.gdx.physics.box2d.joints.FrictionJointDef; public class ApplyForce extends Box2DTest { Body m_body; @Override protected void createWorld(World world) { world.setGravity(new Vector2(0, 0)); float k_restitution = 0.4f; Body ground; { BodyDef bd = new BodyDef(); bd.position.set(0, 20); ground = world.createBody(bd); EdgeShape shape = new EdgeShape(); FixtureDef sd = new FixtureDef(); sd.shape = shape; sd.density = 0; sd.restitution = k_restitution; shape.set(new Vector2(-20, -20), new Vector2(-20, 20)); ground.createFixture(sd); shape.set(new Vector2(20, -20), new Vector2(20, 20)); ground.createFixture(sd); shape.set(new Vector2(-20, 20), new Vector2(20, 20)); ground.createFixture(sd); shape.set(new Vector2(-20, -20), new Vector2(20, -20)); ground.createFixture(sd); shape.dispose(); } { Transform xf1 = new Transform(new Vector2(), 0.3524f * (float) Math.PI); xf1.setPosition(xf1.mul(new Vector2(1, 0))); Vector2[] vertices = new Vector2[3]; vertices[0] = xf1.mul(new Vector2(-1, 0)); vertices[1] = xf1.mul(new Vector2(1, 0)); vertices[2] = xf1.mul(new Vector2(0, 0.5f)); PolygonShape poly1 = new PolygonShape(); poly1.set(vertices); FixtureDef sd1 = new FixtureDef(); sd1.shape = poly1; sd1.density = 4.0f; Transform xf2 = new Transform(new Vector2(), -0.3524f * (float) Math.PI); xf2.setPosition(xf2.mul(new Vector2(-1, 0))); vertices[0] = xf2.mul(new Vector2(-1, 0)); vertices[1] = xf2.mul(new Vector2(1, 0)); vertices[2] = xf2.mul(new Vector2(0, 0.5f)); PolygonShape poly2 = new PolygonShape(); poly2.set(vertices); FixtureDef sd2 = new FixtureDef(); sd2.shape = poly2; sd2.density = 2.0f; BodyDef bd = new BodyDef(); bd.type = BodyType.DynamicBody; bd.angularDamping = 5.0f; bd.linearDamping = 0.1f; bd.position.set(0, 2); bd.angle = (float) Math.PI; bd.allowSleep = false; m_body = world.createBody(bd); m_body.createFixture(sd1); m_body.createFixture(sd2); poly1.dispose(); poly2.dispose(); } { PolygonShape shape = new PolygonShape(); shape.setAsBox(0.5f, 0.5f); FixtureDef fd = new FixtureDef(); fd.shape = shape; fd.density = 1.0f; fd.friction = 0.3f; for (int i = 0; i < 10; i++) { BodyDef bd = new BodyDef(); bd.type = BodyType.DynamicBody; bd.position.set(0, 5 + 1.54f * i); Body body = world.createBody(bd); body.createFixture(fd); float gravity = 10.0f; float I = body.getInertia(); float mass = body.getMass(); float radius = (float) Math.sqrt(2 * I / mass); FrictionJointDef jd = new FrictionJointDef(); jd.localAnchorA.set(0, 0); jd.localAnchorB.set(0, 0); jd.bodyA = ground; jd.bodyB = body; jd.collideConnected = true; jd.maxForce = mass * gravity; jd.maxTorque = mass * radius * gravity; world.createJoint(jd); } shape.dispose(); } } private final Vector2 tmp = new Vector2(); public boolean keyDown(int keyCode) { if (keyCode == Keys.W) { Vector2 f = m_body.getWorldVector(tmp.set(0, -200)); Vector2 p = m_body.getWorldPoint(tmp.set(0, 2)); m_body.applyForce(f, p, true); } if (keyCode == Keys.A) m_body.applyTorque(50, true); if (keyCode == Keys.D) m_body.applyTorque(-50, true); return false; } }