Re: [AD] shader deferred sets

[Jon Rafkind <workmin@xxxxxxxxxx>]

On 03/01/2013 02:52 PM, Peter Wang wrote:
> On Fri, 01 Mar 2013 12:11:16 -0700, Jon Rafkind <workmin@xxxxxxxxxx> wrote:
>> The answer here, as suggested by Trent, is to make the deferred shader copy the float vector. I will make this change if no one beats me to it.
> The same problem applies to al_set_shader_matrix.
>
> Since there are a limited number of elements per vector, it would
> be faster to use fixed sized arrays in the GLSL_DEFERRED_SET structure
> (use a union to reduce the size) instead of allocating per set.

I think the elements of a vector can be infinite because you can set arrays of vectors.

vec4 x;
vec4 x[2];
vec4 x[100];


> But, I'd also like to know why there are deferred sets.

I understand their usage now. You cannot set a variable on a shader until you do glUseProgram first. al_use_shader does this. Without deferred sets you would have to use the shader you are about to set some uniforms on, then set the old shader back. Deferred sets allow you to make changes to a shader without changing the current state.

> Also, why are the al_set_shader_*_array functions are different?
> They are not deferred for the GLSL backend, and not implemented (but
> return success anyway) for the HLSL backend.
>
> Peter
>
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