Same sampler, multiple texture units, OpenGL

Question

With OpenGL (core profile, 4.4), is it "legal" to bind the same sampler object to 2 different texture units at the same time?

My test shows it works, but I don't know if my driver is being forgiving or if it's a feature.

Answer 1

Yes, this is perfectly acceptable as discussed below.

OpenGL 4.4 Core Profile Specification - 8.2 Sampler Objects - pp. 164-165

8.2 Sampler Objects

When a sampler object is bound to a texture unit, its state supersedes that of the texture object bound to that texture unit. If the sampler name zero is bound to a texture unit, the currently bound texture's sampler state becomes active. A single sampler object may be bound to multiple texture units simultaneously.

A sampler object binding is effected with the command:

void glBindSampler (GLuint unit, GLuint sampler);

with unit set to the zero-based index of the texture unit to which to bind the sampler and sampler set to the name of a sampler object returned from a previous call to glGenSamplers .

If the bind is successful no change is made to the state of the bound sampler object, and any previous binding to unit is broken.