将3D世界（arcore锚点姿势）转换为其相应的2D屏幕坐标

将3D世界（arcore锚点/姿势）转换为其相应的2D屏幕坐标

最终，经过几天的调查并从不同的资源中获取了信息，我才能够使它工作。以下是一个代码片段（基于arcore示例Java应用），用于将World坐标（Arcore中的位姿）转换为2D屏幕坐标：

首先，我们需要计算要从世界->屏幕转换的矩阵：

  public float[] calculateWorld2CameraMatrix(float[] modelmtx, float[] viewmtx, float[] prjmtx) {    float scaleFactor = 1.0f;    float[] scaleMatrix = new float[16];    float[] modelXscale = new float[16];    float[] viewXmodelXscale = new float[16];    float[] world2screenMatrix = new float[16];    Matrix.setIdentityM(scaleMatrix, 0);    scaleMatrix[0] = scaleFactor;    scaleMatrix[5] = scaleFactor;    scaleMatrix[10] = scaleFactor;    Matrix.multiplyMM(modelXscale, 0, modelmtx, 0, scaleMatrix, 0);    Matrix.multiplyMM(viewXmodelXscale, 0, viewmtx, 0, modelXscale, 0);    Matrix.multiplyMM(world2screenMatrix, 0, prjmtx, 0, viewXmodelXscale, 0);    return world2screenMatrix;

}

一旦有了这个矩阵，就可以将点从3D世界投影到2D，但是在投影过程中，我们必须将NDC坐标转换为屏幕。以下是执行此转换的方法：

  double[] world2Screen(int screenWidth, int screenHeight, float[] world2cameraMatrix)  {    float[] origin = {0f, 0f, 0f, 1f};    float[] ndcCoord = new float[4];    Matrix.multiplyMV(ndcCoord, 0,  world2cameraMatrix, 0,  origin, 0);    ndcCoord[0] = ndcCoord[0]/ndcCoord[3];    ndcCoord[1] = ndcCoord[1]/ndcCoord[3];    double[] pos_2d = new double[]{0,0};    pos_2d[0] = screenWidth  * ((ndcCoord[0] + 1.0)/2.0);    pos_2d[1] = screenHeight * (( 1.0 - ndcCoord[1])/2.0);    return pos_2d;  }

最后，一个简单的用法示例：

        DisplayMetrics displayMetrics = new DisplayMetrics();        getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);        int height = displayMetrics.heightPixels;        int width = displayMetrics.widthPixels;        // Get projection matrix.        float[] projmtx = new float[16];        camera.getProjectionMatrix(projmtx, 0, 0.1f, 100.0f);        // Get camera matrix and draw.        float[] viewmtx = new float[16];        camera.getViewMatrix(viewmtx, 0);        float[] anchorMatrix = new float[16];        anchor.getPose().toMatrix(anchorMatrix, 0);        float[] world2screenMatrix = virtualObject.calculateWorld2CameraMatrix(anchorMatrix, viewmtx, projmtx);        double[] anchor_2d =  world2Screen(width, height, world2screenMatrix);