[AD] shader conveniences

[Peter Wang <novalazy@xxxxxxxxxx>]

[moving to ad]

On Wed, 06 Mar 2013 11:42:00 -0700, Jon Rafkind <workmin@xxxxxxxxxx> wrote:
> Also I had to add a line to src/bitmap.c that copied the parent's shader to the sub-bitmap in al_create_sub_bitmap
> 
> bitmap->shader = parent->shader;
> 
> Anyway, after implementing my idea below some graphics still don't show up. I guess the default shader is still not being set in some circumstances. Also its a little yucky to set a shader. I have to copy the old target, set the new target, set the shader, then set the old target back.
> 
> if (al_get_bitmap_flags(bitmap) & ALLEGRO_VIDEO_BITMAP){
>       ALLEGRO_BITMAP * old = al_get_target_bitmap();
>       al_set_target_bitmap(bitmap);
>       al_use_shader(shader_default);
>       al_set_target_bitmap(old);
> }
> 
> Could there be a al_use_shader_for_bitmap(ALLEGRO_BITMAP*, ALLEGRO_SHADER*) ?
> 

I agree that's annoying.

I think some more conveniences are in order:

- a bitmap should by default act the same in programmable pipeline mode
  or not, so I guess that means new bitmaps should use a default shader.
  Would this solve the issue above in most cases?

- shaders should be destroyed automatically by the destructor system.

- shaders should implicitly be unused by any bitmaps when the shader is
  destroyed. Otherwise your program will explode if you later target
  one of those bitmaps.

Peter