Is it possible to read floats out from OpenGL ES framebuffer via the iOS texture cache API?

Question

This is related to OpenGL ES 2.0 :glReadPixels() with float or half_float textures.

I want to read out the float values from a framebuffer object after rendering.

On iOS, the following

    GLint ext_type;
    glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE, &ext_type);

really just tells us that glReadPixels only allows GL_UNSIGNED_BYTEs to be read out.

Is there a way to use the textured cache technique related in this article to get around this?

The back story is that I am trying to implement a general matrix multiplication routine for arbitrary-sized matrices (e.g., 100,000 x 100,000) using an OpenGL ES 2.0 fragment shader (similar to Dominik Göddeke's trusty ol' tutorial example). glReadPixel is not being particularly cooperative here because it converts the framebuffer floats to GL_UNSIGNED_BITS, causing a loss of precision.

Answer 1

I asked a similar question and I think the answer is NO, if only because texture caches (as an API) use CoreVideo pixel buffers and they don't currently don't support float formats.