Android OpenGLES 2.0 Buttons

Question

I am a newbee to android OpenGL i am trying to draw buttons using OpenGL I have added a Gesture Listener for the GLSurface View now i have motionevent when ever the user touches. My question is how can i convert motionevent.getx and motionevent.gety (which are in pixel range )to window or Object coordinates of the view?

Answer 1

I Found the solution for this question posting in case if some one requires it.

   public float[] convertToObjectCoordinates(MotionEvent event) {
        float[] worldPos = new float[2];
        float[] invertedMatrix, transformMatrix,
                normalizedInPoint, outPoint, mProjMatrix, mVMatrix;
        invertedMatrix = new float[16];
        transformMatrix = new float[16];
        mProjMatrix = new float[16];
        mProjMatrix = mRenderer.getmProjMatrix();
        mVMatrix = new float[16];
        //Change the Proj and ModelView matrix according to your model and view matrix or you can use your mvpMatrix directly instead of transform Matrix                                     
        Matrix.setLookAtM(mVMatrix, 0, 0, 0, -3, 0, 0, 0f, 0.0f, 1.0f, 0.0f);
        normalizedInPoint = new float[4];
        outPoint = new float[4];
        float y = screenHeight - event.getY();
        setHeightAndWidth();
        normalizedInPoint[0] = (float) ((event.getX()) * 2.0f / screenWidth - 1.0);
        normalizedInPoint[1] = (float) ((y) * 2.0f / screenHeight - 1.0);
        normalizedInPoint[2] = - 1.0f;
        normalizedInPoint[3] = 1.0f;
        Matrix.multiplyMM( transformMatrix, 0, mProjMatrix, 0, mVMatrix, 0);
        Matrix.invertM(invertedMatrix, 0, transformMatrix, 0);
        Matrix.multiplyMV(outPoint, 0, invertedMatrix, 0, normalizedInPoint, 0);
        if (outPoint[3] !=  0.0)
        {
            worldPos[0] = outPoint[0] / outPoint[3];
            worldPos[1] = outPoint[1] / outPoint[3];
        } else {
            Log.e("Error", "Normalised Zero Error");
        }
        return worldPos;
    }

This is remake from the following post for Android OpenGL2.0 : Android OpenGL ES 2.0 screen coordinates to world coordinates EROl's Answer thanks to EROl for his reply.

      public void setHeightAndWidth() {
         screenHeight = this.getHeight();
         screenWidth = this.getWidth();
      }

The above method should be written in the GLSurfaceView class so that it gives the exact view's height and width. If your View occupies complete screen you may also use Display metrics to get complete screen width and height.