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.

5 files changed, 24 insertions, 19 deletions

diff --git a/source/blender/editors/sculpt_paint/paint_image_2d.c b/source/blender/editors/sculpt_paint/paint_image_2d.c
index 79316361e53..b7ce4b2973c 100644
--- a/source/blender/editors/sculpt_paint/paint_image_2d.c
+++ b/source/blender/editors/sculpt_paint/paint_image_2d.c
@@ -402,7 +402,8 @@ static ImBuf *brush_painter_imbuf_new(
 
       if (is_texbrush) {
         brush_imbuf_tex_co(&tex_mapping, x, y, texco);
-        BKE_brush_sample_tex_3d(scene, brush, texco, rgba, thread, pool);
+        const MTex *mtex = &brush->mtex;
+        BKE_brush_sample_tex_3d(scene, brush, mtex, texco, rgba, thread, pool);
         /* TODO(sergey): Support texture paint color space. */
         if (!use_float) {
           IMB_colormanagement_scene_linear_to_display_v3(rgba, display);
@@ -446,6 +447,7 @@ static void brush_painter_imbuf_update(BrushPainter *painter,
 {
   Scene *scene = painter->scene;
   Brush *brush = painter->brush;
+  const MTex *mtex = &brush->mtex;
   BrushPainterCache *cache = &tile->cache;
 
   const char *display_device = scene->display_settings.display_device;
@@ -485,7 +487,7 @@ static void brush_painter_imbuf_update(BrushPainter *painter,
       if (!use_texture_old) {
         if (is_texbrush) {
           brush_imbuf_tex_co(&tex_mapping, x, y, texco);
-          BKE_brush_sample_tex_3d(scene, brush, texco, rgba, thread, pool);
+          BKE_brush_sample_tex_3d(scene, brush, mtex, texco, rgba, thread, pool);
           /* TODO(sergey): Support texture paint color space. */
           if (!use_float) {
             IMB_colormanagement_scene_linear_to_display_v3(rgba, display);
diff --git a/source/blender/editors/sculpt_paint/paint_image_proj.c b/source/blender/editors/sculpt_paint/paint_image_proj.c
index 41d5090b38c..d9aa11a2847 100644
--- a/source/blender/editors/sculpt_paint/paint_image_proj.c
+++ b/source/blender/editors/sculpt_paint/paint_image_proj.c
@@ -5370,7 +5370,7 @@ static void do_projectpaint_thread(TaskPool *__restrict UNUSED(pool), void *ph_v
 
             /* Color texture (alpha used as mask). */
             if (ps->is_texbrush) {
-              MTex *mtex = &brush->mtex;
+              const MTex *mtex = BKE_brush_color_texture_get(brush, OB_MODE_TEXTURE_PAINT);
               float samplecos[3];
               float texrgba[4];
 
@@ -5386,7 +5386,8 @@ static void do_projectpaint_thread(TaskPool *__restrict UNUSED(pool), void *ph_v
 
               /* NOTE: for clone and smear,
                * we only use the alpha, could be a special function */
-              BKE_brush_sample_tex_3d(ps->scene, brush, samplecos, texrgba, thread_index, pool);
+              BKE_brush_sample_tex_3d(
+                  ps->scene, brush, mtex, samplecos, texrgba, thread_index, pool);
 
               copy_v3_v3(texrgb, texrgba);
               custom_mask *= texrgba[3];
diff --git a/source/blender/editors/sculpt_paint/paint_vertex.cc b/source/blender/editors/sculpt_paint/paint_vertex.cc
index 6e3504332ed..acd8b1a6bb1 100644
--- a/source/blender/editors/sculpt_paint/paint_vertex.cc
+++ b/source/blender/editors/sculpt_paint/paint_vertex.cc
@@ -433,9 +433,10 @@ static void paint_and_tex_color_alpha_intern(VPaint *vp,
                                              float r_rgba[4])
 {
   const Brush *brush = BKE_paint_brush(&vp->paint);
-  BLI_assert(brush->mtex.tex != nullptr);
-  if (brush->mtex.brush_map_mode == MTEX_MAP_MODE_3D) {
-    BKE_brush_sample_tex_3d(vc->scene, brush, co, r_rgba, 0, nullptr);
+  const MTex *mtex = BKE_brush_mask_texture_get(brush, OB_MODE_SCULPT);
+  BLI_assert(mtex->tex != nullptr);
+  if (mtex->brush_map_mode == MTEX_MAP_MODE_3D) {
+    BKE_brush_sample_tex_3d(vc->scene, brush, mtex, co, r_rgba, 0, nullptr);
   }
   else {
     float co_ss[2]; /* screenspace */
@@ -445,7 +446,7 @@ static void paint_and_tex_color_alpha_intern(VPaint *vp,
             co_ss,
             (eV3DProjTest)(V3D_PROJ_TEST_CLIP_BB | V3D_PROJ_TEST_CLIP_NEAR)) == V3D_PROJ_RET_OK) {
       const float co_ss_3d[3] = {co_ss[0], co_ss[1], 0.0f}; /* we need a 3rd empty value */
-      BKE_brush_sample_tex_3d(vc->scene, brush, co_ss_3d, r_rgba, 0, nullptr);
+      BKE_brush_sample_tex_3d(vc->scene, brush, mtex, co_ss_3d, r_rgba, 0, nullptr);
     }
     else {
       zero_v4(r_rgba);
diff --git a/source/blender/editors/sculpt_paint/sculpt.c b/source/blender/editors/sculpt_paint/sculpt.c
index 0f71acd3698..95192114429 100644
--- a/source/blender/editors/sculpt_paint/sculpt.c
+++ b/source/blender/editors/sculpt_paint/sculpt.c
@@ -2458,7 +2458,7 @@ float SCULPT_brush_strength_factor(SculptSession *ss,
 {
   StrokeCache *cache = ss->cache;
   const Scene *scene = cache->vc->scene;
-  const MTex *mtex = &br->mtex;
+  const MTex *mtex = BKE_brush_mask_texture_get(br, OB_MODE_SCULPT);
   float avg = 1.0f;
   float rgba[4];
   float point[3];
@@ -2470,7 +2470,7 @@ float SCULPT_brush_strength_factor(SculptSession *ss,
   }
   else if (mtex->brush_map_mode == MTEX_MAP_MODE_3D) {
     /* Get strength by feeding the vertex location directly into a texture. */
-    avg = BKE_brush_sample_tex_3d(scene, br, point, rgba, 0, ss->tex_pool);
+    avg = BKE_brush_sample_tex_3d(scene, br, mtex, point, rgba, 0, ss->tex_pool);
   }
   else {
     float symm_point[3], point_2d[2];
@@ -2499,19 +2499,19 @@ float SCULPT_brush_strength_factor(SculptSession *ss,
       x = symm_point[0];
       y = symm_point[1];
 
-      x *= br->mtex.size[0];
-      y *= br->mtex.size[1];
+      x *= mtex->size[0];
+      y *= mtex->size[1];
 
-      x += br->mtex.ofs[0];
-      y += br->mtex.ofs[1];
+      x += mtex->ofs[0];
+      y += mtex->ofs[1];
 
-      avg = paint_get_tex_pixel(&br->mtex, x, y, ss->tex_pool, thread_id);
+      avg = paint_get_tex_pixel(mtex, x, y, ss->tex_pool, thread_id);
 
       avg += br->texture_sample_bias;
     }
     else {
       const float point_3d[3] = {point_2d[0], point_2d[1], 0.0f};
-      avg = BKE_brush_sample_tex_3d(scene, br, point_3d, rgba, 0, ss->tex_pool);
+      avg = BKE_brush_sample_tex_3d(scene, br, mtex, point_3d, rgba, 0, ss->tex_pool);
     }
   }
 
diff --git a/source/blender/editors/sculpt_paint/sculpt_expand.c b/source/blender/editors/sculpt_paint/sculpt_expand.c
index 655b03bbb36..3133bb2007e 100644
--- a/source/blender/editors/sculpt_paint/sculpt_expand.c
+++ b/source/blender/editors/sculpt_paint/sculpt_expand.c
@@ -167,15 +167,16 @@ static float sculpt_expand_falloff_value_vertex_get(SculptSession *ss,
   if (expand_cache->texture_distortion_strength == 0.0f) {
     return expand_cache->vert_falloff[v_i];
   }
-
-  if (!expand_cache->brush->mtex.tex) {
+  const Brush *brush = expand_cache->brush;
+  const MTex *mtex = BKE_brush_mask_texture_get(brush, OB_MODE_SCULPT);
+  if (!mtex->tex) {
     return expand_cache->vert_falloff[v_i];
   }
 
   float rgba[4];
   const float *vertex_co = SCULPT_vertex_co_get(ss, v);
   const float avg = BKE_brush_sample_tex_3d(
-      expand_cache->scene, expand_cache->brush, vertex_co, rgba, 0, ss->tex_pool);
+      expand_cache->scene, brush, mtex, vertex_co, rgba, 0, ss->tex_pool);
 
   const float distortion = (avg - 0.5f) * expand_cache->texture_distortion_strength *
                            expand_cache->max_vert_falloff;