java - OpenGl ES on android微调光线拾取代码

Question

我使用 min3d 和我在网上找到的一些代码实现了光线拾取，但是当我实现它时，我注意到它有时会关闭一点，这意味着当我点击一个框时，有时会选择错误的框。有时选择的那个甚至不在屏幕上。这首先需要大量代码才能实现，但我调用的主要两个方法如下:

private void rayPicking(float x, float y)
{
    //intersection with near plane
    float[] near = new float[4];
    GLU.gluUnProject(x, scene.getViewport()[3] - y, 0f, scene.getGrabber().mModelView, 0, scene.getGrabber().mProjection, 0, scene.getViewport(), 0, near, 0);
    if (near[3] != 0)
    {
        near[0] = near[0] / near[3];
        near[1] = near[1] / near[3];
        near[2] = near[2] / near[3];
    }
    Number3d near3 = new Number3d(near[0], near[1], near[2]);

    //and far plane
    float[] far = new float[4];
    GLU.gluUnProject(x, scene.getViewport()[3] - y, 1f, scene.getGrabber().mModelView, 0, scene.getGrabber().mProjection, 0, scene.getViewport(), 0, far, 0);
    if (far[3] != 0)
    {
        far[0] = far[0] / far[3];
        far[1] = far[1] / far[3];
        far[2] = far[2] / far[3];
    }
    Number3d far3 = new Number3d(far[0], far[1], far[2]);

    Box firstPicked = null;
    Box currentModel = null;
    Number3d currentCoords = null;
    Number3d firstPickedCoords = new Number3d();

if (!sceneBoxes.isEmpty())
{
    //here we check each model if it was tapped and if several models were tapped, we take only that which is closer to the near clipping plane
    Iterator<Box> itr = sceneBoxes.iterator();
    while (itr.hasNext())
    {
        currentModel = itr.next();
        currentCoords = new Number3d(currentModel.position().x, currentModel.position().y, currentModel.position().z);
        if (picked (far3, near3, currentCoords, 1.2f)) 
            if (firstPicked==null) 
                {
                    firstPicked = currentModel;
                    firstPickedCoords.setAllFrom(currentCoords); 
                }
            else if (Number3d.add(currentCoords, near3).length() < Number3d.add(firstPickedCoords, near3).length()) 
                {
                    firstPicked = currentModel;
                    firstPickedCoords.setAllFrom(currentCoords);
                }
    }
}   

    if (firstPicked != null) // if model picked
     {
        String temp = firstPicked.getTitle();
        String temp2 = firstPicked.getLink();
        Log.w("3d touch working "+temp, "3d touch working "+temp);
        Intent intent = new Intent(CurAct.this, WebViewer.class);
        intent.putExtra("clkURL", temp2);
        intent.putExtra("clkUID", curr_uid);
        intent.putExtra("rid", curr_rid);
        startActivity(intent);

        firstPicked = null;
        temp = null;
        temp2 = null;

    }
}

private boolean picked(Number3d a, Number3d b, Number3d q, float r)
{
    float ab = (float) Math.sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y)+(a.z-b.z)*(a.z-b.z));
    float aq = (float) Math.sqrt((a.x-q.x)*(a.x-q.x)+(a.y-q.y)*(a.y-q.y)+(a.z-q.z)*(a.z-q.z));
    float bq = (float) Math.sqrt((b.x-q.x)*(b.x-q.x)+(b.y-q.y)*(b.y-q.y)+(b.z-q.z)*(b.z-q.z));

    float p = (ab + aq + bq) / 2;

    float hh = (float) Math.sqrt(p * (p - ab) * (p - aq) * (p - bq));
    float h;
    if (ab!=0) h = 2 * hh / ab; else h = 2*hh;

    if (aq<h) h = aq;
    if (bq<h) h = bq;

    if (h<r)return true; else return false;
}

现在我也尝试过实现截锥体剔除，但这样做会减慢速度，因为我没有做太多优化它而且它不是本地运行的。但是，如果有人可以查看并可能给我一些关于如何使其更准确的指示，那就太棒了。这是我调用选择方法的地方。

 _glSurfaceView.setOnTouchListener( 
        new View.OnTouchListener() {

            @Override
            public boolean onTouch(View arg0, MotionEvent e) {

                switch (e.getAction() & MotionEvent.ACTION_MASK) 
                {
                    case MotionEvent.ACTION_DOWN:
                        startX = e.getX();
                        startY = e.getY();
                        trace = 0.0f;
                        time = System.currentTimeMillis();
                        touchMode = DRAG;
                    break;

                    case MotionEvent.ACTION_UP:
                        // we use ray picking only when the tap wasn't longer than 0.5 sec and if we almost didn't move our finger
                        //Log.w("this is touch y"+e.getY()+" viewport is"+scene.getViewport()[3], "this is touch x"+e.getX());
                        if ((System.currentTimeMillis()-time < 500) && (trace<scene.getViewport()[3]*0.075)) rayPicking(e.getX(), e.getY());
                        time = 0;

                    case MotionEvent.ACTION_POINTER_UP:
                        touchMode = NONE;
                    break;
                }
                return true;

            }
            }
        );

Answer 1

你的错误听起来像是你在碰撞检测中犯了一个错误，我在点积函数中有一个错误，导致了一些非常奇怪的结果。你能发布更多你的碰撞算法吗？

我在这里实现了光线拾取:http://android-raypick.blogspot.ca/我没有在这里粘贴代码，因为有很多代码，请随时将您的代码与这段代码进行比较，这段代码已经过测试并且可以正常工作。