Cleanup: GPU: Move towards an explicit Blend state

This make use of the GLStateStack functions for:
- `GPU_blend()`
- `GPU_blend_set_func()`
- `GPU_blend_set_func_separate()`

The goal is to unify them using an explicit state setting.
This will remove the need to use obscure blend functions

3 files changed, 5 insertions, 11 deletions

diff --git a/source/blender/editors/screen/area.c b/source/blender/editors/screen/area.c
index 267fc441f20..68d39246e5f 100644
--- a/source/blender/editors/screen/area.c
+++ b/source/blender/editors/screen/area.c
@@ -135,7 +135,6 @@ static void region_draw_emboss(const ARegion *region, const rcti *scirct, int si
   immUnbindProgram();
 
   GPU_blend(false);
-  GPU_blend_set_func(GPU_SRC_ALPHA, GPU_ONE_MINUS_SRC_ALPHA);
 }
 
 void ED_region_pixelspace(ARegion *region)
diff --git a/source/blender/editors/screen/screen_draw.c b/source/blender/editors/screen/screen_draw.c
index d8d47fb01aa..b0e96c2dae1 100644
--- a/source/blender/editors/screen/screen_draw.c
+++ b/source/blender/editors/screen/screen_draw.c
@@ -308,10 +308,9 @@ static void scrarea_draw_shape_dark(ScrArea *area, char dir, uint pos)
  */
 static void scrarea_draw_shape_light(ScrArea *area, char UNUSED(dir), uint pos)
 {
-  GPU_blend_set_func(GPU_DST_COLOR, GPU_SRC_ALPHA);
-  /* value 181 was hardly computed: 181~105 */
-  immUniformColor4ub(255, 255, 255, 50);
-  /* draw_join_shape(area, dir); */
+  GPU_blend_set_func_separate(
+      GPU_SRC_ALPHA, GPU_ONE_MINUS_SRC_ALPHA, GPU_ONE, GPU_ONE_MINUS_SRC_ALPHA);
+  immUniformColor4ub(255, 255, 255, 25);
 
   immRectf(pos, area->v1->vec.x, area->v1->vec.y, area->v3->vec.x, area->v3->vec.y);
 }
diff --git a/source/blender/editors/sculpt_paint/paint_cursor.c b/source/blender/editors/sculpt_paint/paint_cursor.c
index 63b4516b1cc..0c5e4ea9538 100644
--- a/source/blender/editors/sculpt_paint/paint_cursor.c
+++ b/source/blender/editors/sculpt_paint/paint_cursor.c
@@ -634,8 +634,8 @@ static bool paint_draw_tex_overlay(UnifiedPaintSettings *ups,
     uint texCoord = GPU_vertformat_attr_add(format, "texCoord", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
 
     /* Premultiplied alpha blending. */
-    GPU_blend_set_func(GPU_ONE, GPU_ONE_MINUS_SRC_ALPHA);
     GPU_blend(true);
+    GPU_blend_set_func(GPU_ONE, GPU_ONE_MINUS_SRC_ALPHA);
 
     immBindBuiltinProgram(GPU_SHADER_2D_IMAGE_COLOR);
 
@@ -670,8 +670,6 @@ static bool paint_draw_tex_overlay(UnifiedPaintSettings *ups,
 
     GPU_texture_unbind(texture);
 
-    GPU_blend_set_func(GPU_SRC_ALPHA, GPU_ONE_MINUS_SRC_ALPHA);
-
     if (ELEM(mtex->brush_map_mode, MTEX_MAP_MODE_STENCIL, MTEX_MAP_MODE_VIEW)) {
       GPU_matrix_pop();
     }
@@ -729,8 +727,8 @@ static bool paint_draw_cursor_overlay(
     uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
     uint texCoord = GPU_vertformat_attr_add(format, "texCoord", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
 
-    GPU_blend_set_func(GPU_ONE, GPU_ONE_MINUS_SRC_ALPHA);
     GPU_blend(true);
+    GPU_blend_set_func(GPU_ONE, GPU_ONE_MINUS_SRC_ALPHA);
 
     immBindBuiltinProgram(GPU_SHADER_2D_IMAGE_COLOR);
 
@@ -757,8 +755,6 @@ static bool paint_draw_cursor_overlay(
 
     immUnbindProgram();
 
-    GPU_blend_set_func(GPU_SRC_ALPHA, GPU_ONE_MINUS_SRC_ALPHA);
-
     if (do_pop) {
       GPU_matrix_pop();
     }