本文實(shí)例講述了Android下2d物理引擎Box2d用法。分享給大家供大家參考。具體如下：
程序運(yùn)行的時(shí)候需要加載Jbox2d的庫(kù)，可到以下地址下載（使用的是不帶渲染部分的庫(kù)jbox2d-2.0.1-library-only.jar）：
http://sourceforge.net/projects/jbox2d/
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package com.test;import org.jbox2d.collision.AABB;import org.jbox2d.collision.CircleDef;import org.jbox2d.collision.PolygonDef;import org.jbox2d.common.Vec2;import org.jbox2d.dynamics.Body;import org.jbox2d.dynamics.BodyDef;import org.jbox2d.dynamics.World;import android.app.Activity;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.os.Bundle;import android.os.Handler;import android.view.View;import android.view.Window;import android.view.WindowManager;public class MyBox2d extends Activity { private final static int RATE = 10;//屏幕到現(xiàn)實(shí)世界的比例 10px：1m; private AABB worldAABB; //創(chuàng)建 一個(gè)管理碰撞的世界 private World world; private float timeStep = 1/60;//模擬的的頻率 private int iterations = 10;//迭代越大，模擬約精確，但性能越低 private Body body,body2,body3; private MyView myView; private Handler mHandler; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); getWindow().setFlags(WindowManager.LayoutParams. FLAG_FULLSCREEN , WindowManager.LayoutParams. FLAG_FULLSCREEN); worldAABB = new AABB(); //上下界，以屏幕的左上方為 原點(diǎn)，如果創(chuàng)建的剛體到達(dá)屏幕的邊緣的話，會(huì)停止模擬 worldAABB.lowerBound.set(-100.0f,-100.0f)； worldAABB.upperBound.set(100.0f, 100.0f); //注意這里使用的是現(xiàn)實(shí)世界的單位 Vec2 gravity = new Vec2(0.0f,10.0f); boolean doSleep = true; world = new World(worldAABB, gravity, doSleep);//創(chuàng)建世界 createBox(160, 470, 160, 10, true); createBox1(160, 150, 160, 10, false); createCircle(160, 100, 10); createCircle1(150, 60, 10); timeStep = 1.0f/60.0f; iterations = 10; myView = new MyView(this); setContentView(myView); mHandler = new Handler(); mHandler.post(update); } private Runnable update = new Runnable() { public void run() { world.step(timeStep, iterations);//開始模擬 Vec2 position = body.getPosition(); Vec2 position1 = body2.getPosition(); Vec2 position2 = body3.getPosition(); myView.x=position.x*RATE; myView.y=position.y*RATE; myView.x1=position1.x*RATE; myView.y1=position1.y*RATE; myView.x2=position2.x*RATE; myView.y2=position2.y*RATE; myView.update(); mHandler.postDelayed(update, (long)timeStep*1000); } }; public void createBox(float x,float y,float half_width,float half_height,boolean isStatic){ PolygonDef shape = new PolygonDef(); if(isStatic){shape.density = 0;} else{shape.density = 2.0f;} shape.friction = 0.8f; shape.restitution = 0.3f; shape.setAsBox(half_width/RATE, half_height/RATE); BodyDef bodyDef = new BodyDef(); bodyDef.position.set(x/RATE, y/RATE); Body body1= world.createBody(bodyDef); body1.createShape(shape); body1.setMassFromShapes(); } public void createCircle(float x,float y,float radius){ CircleDef shape = new CircleDef(); shape.density = 7; shape.friction = 0.2f; shape.radius = radius/RATE; BodyDef bodyDef = new BodyDef(); bodyDef.position.set(x/RATE, y/RATE); body2 = world.createBody(bodyDef); body2.createShape(shape); body2.setMassFromShapes(); } public void createCircle1(float x,float y,float radius){ CircleDef shape = new CircleDef(); shape.density = 7; shape.friction = 0.2f; shape.radius = radius/RATE; BodyDef bodyDef = new BodyDef(); bodyDef.position.set(x/RATE, y/RATE); body3 = world.createBody(bodyDef); body3.createShape(shape); body3.setMassFromShapes(); } public void createBox1(float x,float y,float half_width,float half_height,boolean isStatic){ PolygonDef shape = new PolygonDef(); if(isStatic){shape.density = 0;} else{shape.density = 2.0f;} shape.friction = 0.3f; shape.setAsBox(half_width/RATE, half_height/RATE); BodyDef bodyDef = new BodyDef(); bodyDef.position.set(x/RATE, y/RATE); body= world.createBody(bodyDef); body.createShape(shape); body.setMassFromShapes(); } class MyView extends View{ Canvas canvas; public float x=160,y=150; public float x1=160,y1=100; public float x2=150,y2=60; public MyView(Context context) { super(context); } public void drawBox(float x,float y){ Paint mPaint = new Paint(); mPaint.setAntiAlias(true); mPaint.setColor(Color.RED); canvas.drawRect(x-160, y-10, x+160, y+10, mPaint); } public void drawGround(){ Paint mPaint = new Paint(); mPaint.setAntiAlias(true); mPaint.setColor(Color.BLUE); canvas.drawRect(0, 460, 320, 480, mPaint); } public void drawCircle(float x1,float y1){ Paint mPaint = new Paint(); mPaint.setAntiAlias(true); mPaint.setColor(Color.GREEN); canvas.drawCircle(x1, y1, 10, mPaint); } public void update(){ postInvalidate(); } protected void onDraw(Canvas canvas) { super.onDraw(canvas); this.canvas = canvas; drawGround(); drawBox(x, y); drawCircle(x1, y1); drawCircle(x2, y2); } }} |
希望本文所述對(duì)大家的Android程序設(shè)計(jì)有所幫助。
