Texture lookup in vertex shader behaves differently on iPad device vs iPad simulator - OpenGL ES 2.0

Question

I have a vertex shader in which I do a texture lookup to determine gl_Position. I am using this as part of a GPU particle simulation system, where particle positions are sto

Answer 1

I have a feeling GLES on the iPad (or iPhone) does not support texture look up in a vertex shader, but don't quote me.

If it does support texel lookup in vertex shaders, perhaps you have your texture coordinates clipped or wrapping? Because 1.0x1.0 is outside of the texture IIRC.

1.0x1.0 in wrapping mode should be 0.0x0.0. 1.0x1.0 in clipping should be the last texel.