Re: [AD] shader deferred sets

[Jon Rafkind <workmin@xxxxxxxxxx>]

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.

On 03/01/2013 01:11 AM, Jon Rafkind wrote:
> I just ran into an issue where I tried to pass a local float[] to al_set_shader_float_vector and then later call al_use_shader(). Luckily (?) my program didn't crash but the shader got garbage data for the uniform I was trying to set. Whats the point of deferred sets again? I can't see it at the moment, but if there is one then can there also be an API that has an immediate affect. Right now I just call al_set_shader_float_vector immediately followed by al_use_shader and that works.
>
> void draw(){
>   setup_shader_vec4(my_shader, "x", 1, 1, 1, 1);
>   al_use_shader(my_shader);
>   al_draw();
> }
>
> void setup_shader_vec4(ALLEGRO_SHADER * shader, char * name, float v1, float v2, float v3, float v4){
>   float vector[4] = {v1, v2, v3, v4};
>   al_set_shader_float_vector(shader, name, 4, &vector[0], 1);
>   // al_use_shader(shader); // to have an immediate affect
> }
>
> The reason this code doesn't work of course is that the deferred set gets the pointer &vector[0] without copying its contents.
>
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