LibGDX - Box2D的：使用MouseJoint 2個手指

Question

我想通過兩個手指來控制盒象下面這樣：

我有基本MouseJoint implementation：

public class MyMouseJoint{ 

OrthographicCamera cam; 
World world; 

Body groundBody ; 
public MouseJoint mouseJoint = null;  
Body hitBody = null;  
Vector2 target = new Vector2(); 
Vector3 testPoint = new Vector3(); 

QueryCallback callback = new QueryCallback() { 
    @Override 
    public boolean reportFixture (Fixture fixture) { 
     // if the hit fixture's body is the ground body we ignore it    
     if (fixture.getBody() == groundBody) return true; 

     // if the hit point is inside the fixture of the body 
     // we report it 
     if (fixture.testPoint(testPoint.x, testPoint.y)) { 
      hitBody = fixture.getBody(); 
      return false; 
     } else 
      return true; 
    } 
}; 

public MyMouseJoint(OrthographicCamera cam, World world, Body groundBody){ 
    this.cam=cam; 
    this.world=world; 
    this.groundBody = groundBody; 
} 

    //USE THIS FUNCTION IN touchDown 
public void createMouseJoint(float x, float y){ 
    // translate the mouse coordinates to world coordinates 
      testPoint.set(x, y, 0); 
      cam.unproject(testPoint); 

      // ask the world which bodies are within the given 
      // bounding box around the mouse pointer 
      hitBody = null; 
      world.QueryAABB(callback, testPoint.x - 0.1f, testPoint.y - 0.1f, testPoint.x + 0.1f, testPoint.y + 0.1f); 

      if (hitBody != null) { 
       MouseJointDef def = new MouseJointDef(); 
       def.bodyA = groundBody; 
       def.bodyB = hitBody; 
       def.collideConnected = true; 
       def.target.set(testPoint.x, testPoint.y); 
       def.maxForce = 10000.0f * hitBody.getMass(); 
       def.frequencyHz=100; 
       def.dampingRatio=0; 

       mouseJoint = (MouseJoint)world.createJoint(def); 
       hitBody.setAwake(true); 
      } 

} 

    //USE THIS FUNCTION IN touchDragged 
public void dragMouseJoint(float x, float y){ 
    if (mouseJoint != null) { 
     cam.unproject(testPoint.set(x, y, 0)); 
     mouseJoint.setTarget(target.set(testPoint.x, testPoint.y)); 
    } 
} 

    //USE THIS FUNCTION IN touchUp 
public void releaseMouseJoint(){ 
    if (mouseJoint != null) { 
     world.destroyJoint(mouseJoint); 
     mouseJoint = null; 
    } 
} 
} 

如何修改這個類使用2個手指？

Answer 1

你可以做的是創建一個Body數組，並用你的觸摸指針初始化hitbody []。您可以將上面的代碼更改爲以下代碼。

在下面的函數指針varable是，如果你的當前觸摸

public class MyMouseJoint{ 

OrthographicCamera cam; 
World world; 

Body groundBody ; 
public MouseJoint mouseJoint[] = new MouseJoint[2];  
Body hitBody[] = new Body[2];  
Vector2 target = new Vector2(); 
Vector3 testPoint = new Vector3(); 

Body tempBody; 

QueryCallback callback = new QueryCallback() { 
    @Override 
    public boolean reportFixture (Fixture fixture) { 
     // if the hit fixture's body is the ground body we ignore it    
     if (fixture.getBody() == groundBody) return true; 

     // if the hit point is inside the fixture of the body 
     // we report it 
     if (fixture.testPoint(testPoint.x, testPoint.y)) { 
      tempBody = fixture.getBody(); 
      return false; 
     } else 
      return true; 
    } 
}; 
public MyMouseJoint(OrthographicCamera cam, World world, Body groundBody){ 
    this.cam=cam; 
    this.world=world; 
    this.groundBody = groundBody; 
} 

    //USE THIS FUNCTION IN touchDown 
public void createMouseJoint(float x, float y,int pointer){ 
    // translate the mouse coordinates to world coordinates 
      testPoint.set(x, y, 0); 
      cam.unproject(testPoint); 

      // ask the world which bodies are within the given 
      // bounding box around the mouse pointer 
      hitBody[pointer] = null; 

      world.QueryAABB(callback, testPoint.x - 0.1f, testPoint.y - 0.1f, testPoint.x + 0.1f, testPoint.y + 0.1f); 
      hitBody[pointer] = tempBody; 

      if (hitBody[pointer] != null) { 
       MouseJointDef def = new MouseJointDef(); 
       def.bodyA = groundBody; 
       def.bodyB = hitBody[pointer]; 
       def.collideConnected = true; 
       def.target.set(testPoint.x, testPoint.y); 
       def.maxForce = 10000.0f * hitBody[pointer].getMass(); 
       def.frequencyHz=100; 
       def.dampingRatio=0; 

       mouseJoint[pointer] = (MouseJoint)world.createJoint(def); 
       hitBody[pointer].setAwake(true); 
      } 

} 

    //USE THIS FUNCTION IN touchDragged 
public void dragMouseJoint(float x, float y,int pointer){ 
    if (mouseJoint[pointer] != null) { 
     cam.unproject(testPoint.set(x, y, 0)); 
     mouseJoint[pointer].setTarget(target.set(testPoint.x, testPoint.y)); 
    } 
} 

    //USE THIS FUNCTION IN touchUp 
public void releaseMouseJoint(int pointer){ 
    if (mouseJoint[pointer] != null) { 
     world.destroyJoint(mouseJoint[pointer]); 
     mouseJoint[pointer] = null; 
    } 
} 
}