CODEWITHSUNDEEP
opengltypesglslbyteunsigned
l'arbre
l'arbre

Reputation: 719

(unsigned) byte in GLSL

Some of my vertex attributes are single unsigned bytes, I need them in my GLSL fragment shader, not for any "real" calculations, but for comparing them (like enums if you will). I didnt find any unsigned byte or even byte data type in GLSL, so is there a way as using it as an input? If not (which at the moment it seems to be) what is the purpose of GL_UNSIGNED_BYTE?

Upvotes: 15

Views: 15576

Answers (1)

Nicol Bolas
Nicol Bolas

Reputation: 473537

GLSL doesn't deal in sized types (well, not sized types smaller than 32-bits). It only has signed/unsigned integers, floats, doubles, booleans, and vectors/matrices of them. If you pass an unsigned byte as an integer vertex attribute to a vertex shader, then it can read it as a uint type, which is 32-bits in size. Passing integral attributes requires the use of glVertexAttribIPointer/IFormat (note the "I").

The vertex shader can then pass this value to the fragment shader as a uint type (but only with the flat interpolation qualifier). Of course, every fragment for a triangle will get the same value.

Upvotes: 19

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