小程序源码 (鼠标关节拖拽Body).rar

package com.mj; 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.MouseJoint; import org.jbox2d.dynamics.joints.MouseJointDef; 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.MotionEvent; 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; float body1x = 52, body1y = 10, body1w = 10, body1h = 70; float touchX=body1x+body1w/2, touchY=body1y+body1h/2; MouseJoint mouseJoint; boolean bodyFlag; Body test = null; 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); this.setFocusableInTouchMode(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); // ----在物理世界中添加一个矩形Body body1 = createPolygon(body1x + body1w / 2 - body1w / 2, body1y + body1h / 2 - body1h / 2, body1w, body1h, false); // 设置鼠标关节 mouseJoint = createMouseJoint(); mouseJoint.m_gamma = 100;// 弹性度 } public void surfaceCreated(SurfaceHolder holder) { //添加边界 createPolygon(5, 5, this.getWidth() - 10, 2, true); createPolygon(5, this.getHeight() - 10, this.getWidth() - 10, 2, true); createPolygon(5, 5, 2, this.getHeight() - 10, true); createPolygon(this.getWidth() - 10, 5, 2, this.getHeight() - 10, true); flag = true; th = new Thread(this); th.start(); } @Override public boolean onTouchEvent(MotionEvent event) { touchX = event.getX(); touchY = event.getY(); //唤醒body1 body1.wakeUp(); mouseJoint.m_target.set(event.getX() / RATE, event.getY() / RATE); return true; } // 鼠标关节 public MouseJoint createMouseJoint() { MouseJointDef mjd = new MouseJointDef(); //设置鼠标关节的第一个Body实例（默认使用接地Body） mjd.body1 = world.getGroundBody(); //设置鼠标关节的第二个Body实例(被拖拽的Body) mjd.body2 = body1; //设置目标点的X坐标 mjd.target.x = body1.getPosition().x; //设置目标点的Y坐标 mjd.target.y = body1.getPosition().y; // body1.allowSleeping(false);//设置body1永不休眠 // 设置鼠标关节的目标位置 mjd.maxForce = 100;// 拉力 //由World来创建鼠标关节 MouseJoint mj = (MouseJoint) world.createJoint(mjd); return mj; } 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 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; } canvas.drawLine(body1.getPosition().x * RATE, body1.getPosition().y * RATE, touchX, touchY, paint); } } catch (Exception e) { Log.e("Himi", "myDraw is Error!"); } finally { if (canvas != null) sfh.unlockCanvasAndPost(canvas); } } 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; } }