iOS OpenGL ES 2.0 Shader's limits

Question

Are some limits of shader's size or variable's number in fragment shader?

I've fragment shader, which returns empty image after some threshold size of code. I think, that problem is in limit of shader's size or number of variables.

I check my shader program after compilation - all is ok.

Apple said:

OpenGL ES limits the number of each variable type you can use in a vertex or fragment shader. The OpenGL ES specification doesn’t require implementations to provide a software fallback when these limits are exceeded; instead, the shader simply fails to compile or link.

Khronos said:

2 Length of Shader Executable This is defined by the conformance tests. 3 Usage of Temporary Variables The maximum number of variables is defined by the conformance tests.

But I can't find value of this limits.

UPDATE:

Sometimes application is interrupted on glFlush or glDrawArrays with EXC_BAD_ACCESS, if image is big.

SOLVED

Problem was in too long loop and from whence in long calculation time. Shader is no big, but very complexity.

UPDATE

Same problem: GPUImage Kuwahara filter on iPhone 4S

I don't think you can query the maximum length. The compilation should fail if you exceed it, though. — Reto Koradi
I think, that problem is in the long loop. But I can't do that otherwise. I think, that principally another approach must be implemented here. — George
Post your shader. That's going to be the only way to get help. — badweasel

ovikoomikko ovikoomikko · Accepted Answer · 2014-12-24T08:48:17

If you are checking the results of your shader compilations and linking (like instructed in Listing 10-1 in Apple's best practices.) and there are no errors, something else causes your empty image.

If you are not checking the log, you should start checking :)

iOS OpenGL ES 2.0 Shader's limits

1 Answers