Fix T84053: Mask overlay in image editor not working

The mask overlay wasn't part of the overlay engine. The reasoning nehind
this was that more editors used the mask overlay and most of them used
old drawing code. This patch adds the mask overlay drawing to the draw
overlay engine. This code path will only be used by the image editor
VSE, Compositor and Movie Clip editor will still use the previous
method.

During this patch some alternatives have been researched:
1. `ED_mask_draw_region`: this would lead to different code paths when
   drawing in the image editor, and some hacks to retrieve the correct
   framebuffer.
2. Add mask drawing to image engine: Would lead to incorrect color
   management when viewing the mask.
3. Add mask drawing to image engine and overlay engine: Would lead to
   duplicated code.
4. Add mask drawing to overlay engine and for combined overlay select
   the correct framebuffer.

Option 4 was chosen as the exception (switching framebuffers) can be
done without hacks. The code stays clean.

1 files changed, 15 insertions, 3 deletions

diff --git a/source/blender/draw/engines/overlay/overlay_private.h b/source/blender/draw/engines/overlay/overlay_private.h
index 3355e1bdf16..3aee391c281 100644
--- a/source/blender/draw/engines/overlay/overlay_private.h
+++ b/source/blender/draw/engines/overlay/overlay_private.h
@@ -34,9 +34,9 @@ extern "C" {
 #  define USE_GEOM_SHADER_WORKAROUND 0
 #endif
 
-/* Needed for eSpaceImage_UVDT_Stretch */
+/* Needed for eSpaceImage_UVDT_Stretch and eMaskOverlayMode */
+#include "DNA_mask_types.h"
 #include "DNA_space_types.h"
-
 /* Forward declarations */
 struct ImBuf;
 
@@ -99,6 +99,7 @@ typedef struct OVERLAY_PassList {
   DRWPass *edit_uv_stretching_ps;
   DRWPass *edit_uv_tiled_image_borders_ps;
   DRWPass *edit_uv_stencil_ps;
+  DRWPass *edit_uv_mask_ps;
   DRWPass *extra_ps[2];
   DRWPass *extra_blend_ps;
   DRWPass *extra_centers_ps;
@@ -368,18 +369,23 @@ typedef struct OVERLAY_PrivateData {
     bool do_tiled_image_overlay;
     bool do_tiled_image_border_overlay;
     bool do_stencil_overlay;
+    bool do_mask_overlay;
 
     bool do_faces;
     bool do_face_dots;
 
     float uv_opacity;
+
+    int image_size[2];
+    float image_aspect[2];
+
     /* edge drawing */
     OVERLAY_UVLineStyle line_style;
     float dash_length;
     int do_smooth_wire;
 
     /* stretching overlay */
-    float aspect[2];
+    float uv_aspect[2];
     eSpaceImage_UVDT_Stretch draw_type;
     ListBase totals;
     float total_area_ratio;
@@ -389,6 +395,11 @@ typedef struct OVERLAY_PrivateData {
     struct Image *stencil_image;
     struct ImBuf *stencil_ibuf;
     void *stencil_lock;
+
+    /* mask overlay */
+    Mask *mask;
+    eMaskOverlayMode mask_overlay_mode;
+    GPUTexture *mask_texture;
   } edit_uv;
   struct {
     bool transparent;
@@ -690,6 +701,7 @@ GPUShader *OVERLAY_shader_edit_uv_stretching_area_get(void);
 GPUShader *OVERLAY_shader_edit_uv_stretching_angle_get(void);
 GPUShader *OVERLAY_shader_edit_uv_tiled_image_borders_get(void);
 GPUShader *OVERLAY_shader_edit_uv_stencil_image(void);
+GPUShader *OVERLAY_shader_edit_uv_mask_image(void);
 GPUShader *OVERLAY_shader_extra(bool is_select);
 GPUShader *OVERLAY_shader_extra_groundline(void);
 GPUShader *OVERLAY_shader_extra_wire(bool use_object, bool is_select);