GPUTexture: Small refactor.

This includes a few modification:
 - The biggest one is call glActiveTexture before doing any call to
   glBindTexture for rendering purpose (uniform value depends on it).
   This is also better to know what's going on when rendering UI. So if
   there is missing UI elements because of this commit look for this first.
   This allows us to have "less calls" to glActiveTexture (I did not
   measure the final count) and less checks inside GPU_texture.

 - Remove use of GL_TEXTURE0 as a uniform value in a few places.

 - Be more strict and use BLI_assert for bad usage of GPU_texture functions.

 - Disable filtering for integer and stencil textures (not supported by
   OGL specs).

 - Replace bools inside GPUTexture by a bitflag supporting more options to
   identify texture types.

1 files changed, 3 insertions, 1 deletions

diff --git a/source/blender/gpu/GPU_texture.h b/source/blender/gpu/GPU_texture.h
index 0fde0edcf2b..72e3859a5a8 100644
--- a/source/blender/gpu/GPU_texture.h
+++ b/source/blender/gpu/GPU_texture.h
@@ -196,10 +196,12 @@ void GPU_texture_framebuffer_set(GPUTexture *tex, struct GPUFrameBuffer *fb, int
 int GPU_texture_target(const GPUTexture *tex);
 int GPU_texture_width(const GPUTexture *tex);
 int GPU_texture_height(const GPUTexture *tex);
-int GPU_texture_format(const GPUTexture *tex);
+GPUTextureFormat GPU_texture_format(const GPUTexture *tex);
 int GPU_texture_samples(const GPUTexture *tex);
+bool GPU_texture_cube(const GPUTexture *tex);
 bool GPU_texture_depth(const GPUTexture *tex);
 bool GPU_texture_stencil(const GPUTexture *tex);
+bool GPU_texture_integer(const GPUTexture *tex);
 int GPU_texture_opengl_bindcode(const GPUTexture *tex);
 
 #ifdef __cplusplus