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.

3 files changed, 5 insertions, 3 deletions

diff --git a/source/blender/windowmanager/intern/wm_draw.c b/source/blender/windowmanager/intern/wm_draw.c
index 4a6bc2ded28..cfd3291293c 100644
--- a/source/blender/windowmanager/intern/wm_draw.c
+++ b/source/blender/windowmanager/intern/wm_draw.c
@@ -505,8 +505,6 @@ void wm_triple_draw_textures(wmWindow *win, wmDrawTriple *triple, float alpha)
 	immUnbindProgram();
 
 	glBindTexture(GL_TEXTURE_2D, 0);
-	if (activeTex != 0)
-		glActiveTexture(GL_TEXTURE0);
 }
 
 static void wm_triple_copy_textures(wmWindow *win, wmDrawTriple *triple)
diff --git a/source/blender/windowmanager/intern/wm_operators.c b/source/blender/windowmanager/intern/wm_operators.c
index 53098ea58b2..fb8130f8954 100644
--- a/source/blender/windowmanager/intern/wm_operators.c
+++ b/source/blender/windowmanager/intern/wm_operators.c
@@ -2504,6 +2504,7 @@ static void radial_control_set_tex(RadialControl *rc)
 				glBindTexture(GL_TEXTURE_2D, rc->gltex);
 				glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, ibuf->x, ibuf->y, 0,
 				             GL_RED, GL_FLOAT, ibuf->rect_float);
+				glBindTexture(GL_TEXTURE_2D, 0);
 				MEM_freeN(ibuf->rect_float);
 				MEM_freeN(ibuf);
 			}
@@ -2544,6 +2545,7 @@ static void radial_control_paint_tex(RadialControl *rc, float radius, float alph
 
 		unsigned int texCoord = GWN_vertformat_attr_add(format, "texCoord", GWN_COMP_F32, 2, GWN_FETCH_FLOAT);
 
+		glActiveTexture(GL_TEXTURE0);
 		glBindTexture(GL_TEXTURE_2D, rc->gltex);
 
 		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
@@ -2555,7 +2557,7 @@ static void radial_control_paint_tex(RadialControl *rc, float radius, float alph
 		immBindBuiltinProgram(GPU_SHADER_2D_IMAGE_MASK_UNIFORM_COLOR);
 
 		immUniformColor3fvAlpha(col, alpha);
-		immUniform1i("image", GL_TEXTURE0);
+		immUniform1i("image", 0);
 
 		/* set up rotation if available */
 		if (rc->rot_prop) {
diff --git a/source/blender/windowmanager/intern/wm_stereo.c b/source/blender/windowmanager/intern/wm_stereo.c
index b70769b2d51..b52fc4ae213 100644
--- a/source/blender/windowmanager/intern/wm_stereo.c
+++ b/source/blender/windowmanager/intern/wm_stereo.c
@@ -204,6 +204,7 @@ static void wm_method_draw_stereo3d_sidebyside(wmWindow *win)
 	unsigned int pos = GWN_vertformat_attr_add(format, "pos", GWN_COMP_F32, 2, GWN_FETCH_FLOAT);
 
 	immBindBuiltinProgram(GPU_SHADER_2D_IMAGE_ALPHA);
+	glActiveTexture(GL_TEXTURE0);
 
 	for (view = 0; view < 2; view ++) {
 		drawdata = BLI_findlink(&win->drawdata, (view * 2) + 1);
@@ -266,6 +267,7 @@ static void wm_method_draw_stereo3d_topbottom(wmWindow *win)
 	unsigned int pos = GWN_vertformat_attr_add(format, "pos", GWN_COMP_F32, 2, GWN_FETCH_FLOAT);
 
 	immBindBuiltinProgram(GPU_SHADER_2D_IMAGE_ALPHA);
+	glActiveTexture(GL_TEXTURE0);
 
 	for (view = 0; view < 2; view ++) {
 		drawdata = BLI_findlink(&win->drawdata, (view * 2) + 1);