Would it make sense to add a SHADER_LOC_USER ?

[neonrust]

Currently, Raylib defines some SHADER_LOC_... constants which it automatically uses to set the available locations in LoadShader().

If I want to add some of my own locations, like in the example "basic_lighting", where it uses a bunch, it would be nice to be able to look them up once, and store/cache them in the Shader::locs array. The tricky part is that it's not obvious which of those slots are not used, nor how many are possible to store there.

Looking in the source, config.h and rlgl.c, it becomes clear that the last predefined location is id = 25 (at the moment) and the locs array is allocated with size 32.

So, I propose adding a SHADER_LOC_USER constant, which would be defined as <last predefined location> + 1 (in practice, just last in the ShaderLocationIndex enum). This enables the developer to know that anything above SHADER_LOC_USER is available.
So, defining constants for custom locations becomes simpler, e.g.: SHADER_LOC_FOG_DAMPNESS = SHADER_LOC_USER + 3 (completely fictitious 😄).

Also, the RL_MAX_SHADER_LOCATIONS could be bumped to like 128 (or 256 even). Alternatively, the max could be settable at run-time, before the first shader is created (i.e. if the Shader struct becomes too large in some context).

Note that the locs array doesn't affect how many locations actually exist in a shader, it's just client-side storage for remembering (some of) them 😉.

edit: rephrased a bit