package com.rj;
import org.jbox2d.collision.AABB;
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 org.jbox2d.dynamics.joints.RevoluteJoint;
import org.jbox2d.dynamics.joints.RevoluteJointDef;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.SurfaceHolder.Callback;
public class MySurfaceView extends SurfaceView implements Callback, Runnable {
private Thread th;
private SurfaceHolder sfh;
private Canvas canvas;
private Paint paint;
private boolean flag;
// ----添加一个物理世界---->>
final float RATE = 30;
World world;
AABB aabb;
Vec2 gravity;
float timeStep = 1f / 60f;
int iterations = 10;
// ------>>旋转关节
Body body1, body2;
float body1x =40, body1y = 10, body1w = 10, body1h = 70, body2w = 80, body2h = 30;
public MySurfaceView(Context context) {
super(context);
this.setKeepScreenOn(true);
sfh = this.getHolder();
sfh.addCallback(this);
paint = new Paint();
paint.setStyle(Style.STROKE);
paint.setAntiAlias(true);
this.setFocusable(true);
// --添加一个物理世界--->>
aabb = new AABB();
gravity = new Vec2(0, 10);
aabb.lowerBound.set(-100, -100);
aabb.upperBound.set(100, 100);
world = new World(aabb, gravity, true);
// ----在物理世界中添加两个矩形Body
body1 = createPolygon(body1x , body1y, body1w, body1h, false);
body2 = createPolygon(body1x+body1w/2-body2w/2, body1y+body1h/2-body2h/2, body2w, body2h, true);
// 设置旋转关节
createRevoluteJoint();
}
public void surfaceCreated(SurfaceHolder holder) {
flag = true;
th = new Thread(this);
th.start();
}
public RevoluteJoint createRevoluteJoint() {
//创建一个旋转关节的数据实例
RevoluteJointDef rjd = new RevoluteJointDef();
//初始化旋转关节数据
rjd.initialize(body1, body2, body1.getWorldCenter());
rjd.maxMotorTorque = 1;// 马达的预期最大扭矩
rjd.motorSpeed =20;//马达最终扭矩
rjd.enableMotor = true;// 启动马达
//利用world创建一个旋转关节
RevoluteJoint rj = (RevoluteJoint)world.createJoint(rjd);
return rj ;
}
public Body createPolygon(float x, float y, float width, float height, boolean isStatic) {
PolygonDef pd = new PolygonDef();
if (isStatic) {
pd.density = 0;
} else {
pd.density = 1;
}
pd.friction = 0.8f;
pd.restitution = 0.3f;
pd.setAsBox(width / 2 / RATE, height / 2 / RATE);
BodyDef bd = new BodyDef();
bd.position.set((x + width / 2) / RATE, (y + height / 2) / RATE);
Body body = world.createBody(bd);
body.m_userData = new MyRect(x, y, width, height);
body.createShape(pd);
body.setMassFromShapes();
return body;
}
public void myDraw() {
try {
canvas = sfh.lockCanvas();
if (canvas != null) {
canvas.drawColor(Color.WHITE);
Body body = world.getBodyList();
for (int i = 1; i < world.getBodyCount(); i++) {
((MyRect) body.m_userData).draw(canvas, paint);
body = body.m_next;
}
}
} catch (Exception e) {
Log.e("Himi", "myDraw is Error!");
} finally {
if (canvas != null)
sfh.unlockCanvasAndPost(canvas);
}
}
public void Logic() {
world.step(timeStep, iterations);
Body body = world.getBodyList();
for (int i = 1; i < world.getBodyCount(); i++) {
MyRect mc = (MyRect) body.m_userData;
mc.setX(body.getPosition().x * RATE - mc.w / 2);
mc.setY(body.getPosition().y * RATE - mc.h / 2);
mc.setAngle((float) (body.getAngle() * 180 / Math.PI));
body = body.m_next;
}
}
public void run() {
while (flag) {
myDraw();
Logic();
try {
Thread.sleep((long) timeStep * 1000);
} catch (Exception ex) {
Log.e("Himi", "Thread is Error!");
}
}
}
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
public void surfaceDestroyed(SurfaceHolder holder) {
flag = false;
}
}