Should we have another shader that combines texture and a uniform color or update GPU_SHADER_3D_IMAGE_MODULATE_ALPHA to do this job?

In general each shader should do exactly what you want -- no more no less. So make a new shader if you want different behavior. Sounds like a GPU_SHADER_2D_IMAGE_MODULATE_COLOR, yes? Would you like to do the GLSL part?

Right now it seems silly to have 2D and 3D versions of some shaders, but it will make more sense when the 2D matrix stack is ready!

Ah, forgot to mention: while testing this patch I found unfreed memory blocks. It happens if you go to Texture Painting, assign a texture (the object needs to have UV coords and a channel to paint on, just press the buttons indicated in the tool shelf in tex painting mode to add them). The error:

Error: Not freed memory blocks: 2, total unfreed memory 0.004738 MB

Here the info by running Blender in debug mode:

Error: Not freed memory blocks: 2, total unfreed memory 0.004738 MB
ImBuf_struct len: 2480 0x7f320349b438
imb_addrectImBuf len: 4 0x7f32034c7088

I debugged for some minutes yesterday, but will need to investigate more to see where it should be freed.

In D2311#53445, @Mike Erwin (merwin) wrote:

Should we have another shader that combines texture and a uniform color or update GPU_SHADER_3D_IMAGE_MODULATE_ALPHA to do this job?

In general each shader should do exactly what you want -- no more no less. So make a new shader if you want different behavior. Sounds like a GPU_SHADER_2D_IMAGE_MODULATE_COLOR, yes? Would you like to do the GLSL part?

Cool, will be fun to do it, thanks : ).