如何平移放大缩小min3d中的功能Android

Question

我是OpenGl Devloper中的新成员，我想在OpenGl android中呈现3D模型，因此我选择了min3d框架库。

我想平移放大缩小功能，为我min3d

像模型，像照相机放大缩小，我有3dmodel小姐，我想缩小她的脸上没有规模的任何解决方案目的？

Answer 1

您需要更改相机位置。我建议你定义一些额外的参数center和distance，因为你想平移。

当您有缩放手势时，只需将缩放比例应用到距离distance *= scale（或distance = originalDistance*scale，具体取决于实施）。

在平底锅上，您只需将center移动距离center.x += (newXOnScreen-oldXOnScreen)*speedFactor和center.y += (newYOnScreen-oldYOnScreen)*speedFactor即可。速度因素在这里可能是恒定的（随着它的变化而变化），但最好也可以将它乘以缩放比例，如果它非常接近，则中心移动得更少。

既然你有这2个参数，你需要将它们应用到相机。假设你的模型位置为(0,0,0)：

scene.camera.position = {center.x, center.y, center.z-distance} 
scene.camera.target = {center.x, center.y, center.z} 
scene.camera.up = {0, 1, 0} 

Answer 2

以下代码片段适用于我。这不是完整的代码，但我刚刚添加了在min3d框架中执行三维对象的缩放和拖动的部分。我放在一起通过下面的在线教程中的代码here和修改根据应用

//import statements 
    public class threedviewActivity extends RendererActivity { 
     private Object3dContainer Object3D; 
     private ScaleGestureDetector mScaleDetector; 
     private float mScaleFactor = 1.f,mLastTouchX,mLastTouchY,mPosX,mPosY; 
     private int mActivePointerId = INVALID_POINTER_ID,flag; 

     @Override 
     public void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       mScaleDetector = new ScaleGestureDetector(threedviewActivity.this, new ScaleListener()); 

     } 

     @Override 
     public boolean onTouchEvent(MotionEvent ev) { 
       // Let the ScaleGestureDetector inspect all events. 
       mScaleDetector.onTouchEvent(ev); 
       final int action = MotionEventCompat.getActionMasked(ev); 

       switch (action) { 
        case MotionEvent.ACTION_DOWN: { 
         final int pointerIndex = MotionEventCompat.getActionIndex(ev); 
         final float x = MotionEventCompat.getX(ev, pointerIndex); 
         final float y = MotionEventCompat.getY(ev, pointerIndex); 

         mLastTouchX = x; 
         mLastTouchY = y; 

         mActivePointerId = MotionEventCompat.getPointerId(ev, 0); 
         updateScene(); 
         break; 
        } 

        case MotionEvent.ACTION_MOVE: { 
         // Find the index of the active pointer and fetch its position 
         final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId); 
         final float x = MotionEventCompat.getX(ev, pointerIndex); 
         final float y = MotionEventCompat.getY(ev, pointerIndex); 

         final float dx = x - mLastTouchX; 
         final float dy = y - mLastTouchY; 

         mPosX += dx; 
         mPosY += dy; 

         // Remember this touch position for the next move event 
         mLastTouchX = x; 
         mLastTouchY = y; 
         flag = 1; 
         updateScene(); 
         break; 
        } 

        case MotionEvent.ACTION_UP: { 
         mActivePointerId = INVALID_POINTER_ID; 
         break; 
        } 

        case MotionEvent.ACTION_CANCEL: { 
         mActivePointerId = INVALID_POINTER_ID; 
         break; 
        } 

        case MotionEvent.ACTION_POINTER_UP: { 

         final int pointerIndex = MotionEventCompat.getActionIndex(ev); 
         final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex); 

         if (pointerId == mActivePointerId) { 
           // This was our active pointer going up. Choose a new 
          // active pointer and adjust accordingly. 
          final int newPointerIndex = pointerIndex == 0 ? 1 : 0; 
          mLastTouchX = MotionEventCompat.getX(ev, newPointerIndex); 
          mLastTouchY = MotionEventCompat.getY(ev, newPointerIndex); 
          mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex); 
         } 
         break; 
        } 
      } 
      return true; 
     } 

     @Override 
     public void initScene() 
     { 
       //this is where you initialize your 3d object. Check below for links for tutorials on that. 
     } 

     private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener { 
       @Override 
       public boolean onScale(ScaleGestureDetector detector) { 
        mScaleFactor *= detector.getScaleFactor(); 

        // Don't let the object get too small or too large. 
        mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 5.0f)); 
        Object3D.scale().x = Object3D.scale().y = Object3D.scale().z = mScaleFactor*1.5f; 
        flag = 0; 
        updateScene(); 
        return true; 

       } 
     } 

     @Override 
     public void updateScene() 
     { 
       if(flag == 1) 
       { 
        Object3D.position().x = mPosX/100; 
        Object3D.position().y = -mPosY/100; 
       } 
     } 

    } 

对于initalizing min3D，跟着你必须的lookAt矩阵接入教程here和here