i try to implement a coordinate picking function with OpenGL ES 2.0.
I cannot implement the two versions i've implemented in my desktop version.

Version 1 is to render every triangle in a unique color, which represent the index of the triangle and than to calculate the coordinate with an raycast. This version doesn't work, because in the OpenGL ES GLSL Version 1.0 is no variable GL_PrimitiveID an bitwise shifting is also not possible.

Version 2 is to render the coordinate as the value of a floating-point texture, but floating-point texture is not available in OpenGL ES 2.0.

Has anybody another idea what I can implement? I don't want to raycast every triangle, because it's not so performant.

Thanks for help and any ideas.