Brush: Wrap mtex/mask_tex around functions.

`Brush` has two attributes for holding texture information (`MTex`).
One for color textures (`mtex`) and one for mask textures (`mask_mtex`).

Unfortunately sculpt mode due to reasons used `mtex` to store mask textures.
Changes like brush asset/paint mode require modes/tools to read the mask/color texture from
one place.

To start sanatizing this we isolate the attributes in functions.
`BKE_brush_color_texture_get` and `BKE_brush_mask_texture_get`. All object
paint modes should use these functions.

1 files changed, 20 insertions, 2 deletions

diff --git a/source/blender/blenkernel/intern/brush.cc b/source/blender/blenkernel/intern/brush.cc
index 20d86ea5a2d..6f1435e90b8 100644
--- a/source/blender/blenkernel/intern/brush.cc
+++ b/source/blender/blenkernel/intern/brush.cc
@@ -1974,19 +1974,37 @@ void BKE_brush_curve_preset(Brush *b, eCurveMappingPreset preset)
   BKE_curvemapping_changed(cumap, false);
 }
 
+const struct MTex *BKE_brush_mask_texture_get(const struct Brush *brush,
+                                              const eObjectMode object_mode)
+{
+  if (object_mode == OB_MODE_SCULPT) {
+    return &brush->mtex;
+  }
+  return &brush->mask_mtex;
+}
+
+const struct MTex *BKE_brush_color_texture_get(const struct Brush *brush,
+                                               const eObjectMode object_mode)
+{
+  if (object_mode == OB_MODE_SCULPT) {
+    return &brush->mask_mtex;
+  }
+  return &brush->mtex;
+}
+
 float BKE_brush_sample_tex_3d(const Scene *scene,
                               const Brush *br,
+                              const MTex *mtex,
                               const float point[3],
                               float rgba[4],
                               const int thread,
                               struct ImagePool *pool)
 {
   UnifiedPaintSettings *ups = &scene->toolsettings->unified_paint_settings;
-  const MTex *mtex = &br->mtex;
   float intensity = 1.0;
   bool hasrgb = false;
 
-  if (!mtex->tex) {
+  if (mtex == nullptr || mtex->tex == nullptr) {
     intensity = 1;
   }
   else if (mtex->brush_map_mode == MTEX_MAP_MODE_3D) {