render to floating point texture under iOS

Question

The iPad now supports the OES_texture_half_float extension. Unfortunately I'm having trouble binding a floating-point texture to a framebuffer object. Here's my attempt:

GLuint textureHandle;
glGenTextures(1, &textureHandle);
glBindTexture(GL_TEXTURE_2D, textureHandle);
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, 256, 256, 0, GL_LUMINANCE, GL_HALF_FLOAT_OES, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
assert(GL_NO_ERROR == glGetError()); // this passes

GLuint fboHandle;
glGenFramebuffers(1, &fboHandle);
glBindFramebuffer(GL_FRAMEBUFFER, fboHandle);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textureHandle, 0);
assert(GL_FRAMEBUFFER_COMPLETE == glCheckFramebufferStatus(GL_FRAMEBUFFER)); // this asserts

This works fine when replacing GL_HALF_FLOAT_OES with GL_UNSIGNED_BYTE.

Is this a limitation with iOS or am I doing something incorrectly?

Answer 1

I posted a similar question on this topic here.

It seems that the OES_texture_float extension is currently only supported on iPhone 4S and iPad 2, even though it's not explicitly mentioned in Apple's guide.

Thanks to kal21 for pointing this out.