在Android OpenGL ES 2.0中，使用gluUnProject将触摸映射到x,y连线在z=0平面上

I've drawn a grid at z=0 in OpenGL 2.0 ES, and just want to convert touch inputs to x/y coordinates on that plane. It seems like this is best done through ray tracing, which involves running gluUnProject on 0 and 1, then creating a ray, solving that ray for z=0?I've drawn a grid at z=0 in OpenGL 2.0 ES, and