OpenGL ES 2.0 on iPhone - How many texture units can i use?

Question

In apple's docs:(http://developer.apple.com/library/ios/#documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/OpenGLESPlatforms/OpenGLESPlatforms.html)

it says that for "OpenGL ES 1.1 on the PowerVR SGX" "There are 8 texture units available."

it doesn't say how many units are available on OpenGL ES 2.0, does that mean there is no limit?

Answer 1

Rather than asking and getting an answer that may or may not be correct in the future, your app should be checking programmatically at runtime using something like this:

glGetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS, &MaxTextureUnits);

Note that there are also separate numbers for the number of allowed texture units in a vertex shader and a fragment shader. They would use the constants GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS and GL_MAX_TEXTURE_IMAGE_UNITS. The COMBINED number is the number available to both at the same time.

Answer 2

There is a detailed listing of all the hardware across iPhones and iPads on Apple's iOS Device Compatibility Reference

Based on this, you are safe with using upto 8 Texture units on any iOS device.