Fix T42561 (semi feature request/comeback) UVs in image editor can get

too crowded.

UVs in the same layer can be used for many images. It used to be
possible to filter UV faces based on the image, but this is impossible
now due to the way the system works, so I added an option to allow
filtering UVs based on active material index.

Rationale on using option and not being smart here (options are bad tm)
is that for some workflows, such as preserving image space by using the
same image for many materials, people might want to turn this off.

6 files changed, 21 insertions, 2 deletions

diff --git a/release/scripts/startup/bl_ui/space_image.py b/release/scripts/startup/bl_ui/space_image.py
index bdb0ca7aa15..1e3a7433e25 100644
--- a/release/scripts/startup/bl_ui/space_image.py
+++ b/release/scripts/startup/bl_ui/space_image.py
@@ -82,6 +82,7 @@ class IMAGE_MT_view(Menu):
         layout.prop(uv, "show_other_objects")
         if paint.brush and (context.image_paint_object or sima.mode == 'PAINT'):
             layout.prop(uv, "show_texpaint")
+            layout.prop(uv, "texpaint_filter_mat")
 
         layout.separator()
 
diff --git a/source/blender/editors/space_image/space_image.c b/source/blender/editors/space_image/space_image.c
index 42c1b920f39..770582f4afa 100644
--- a/source/blender/editors/space_image/space_image.c
+++ b/source/blender/editors/space_image/space_image.c
@@ -791,7 +791,7 @@ static void image_main_area_draw(const bContext *C, ARegion *ar)
 #endif
 }
 
-static void image_main_area_listener(bScreen *UNUSED(sc), ScrArea *UNUSED(sa), ARegion *ar, wmNotifier *wmn)
+static void image_main_area_listener(bScreen *UNUSED(sc), ScrArea *sa, ARegion *ar, wmNotifier *wmn)
 {
 	/* context changes */
 	switch (wmn->category) {
@@ -803,6 +803,14 @@ static void image_main_area_listener(bScreen *UNUSED(sc), ScrArea *UNUSED(sa), A
 			if (wmn->action == NA_PAINTING)
 				ED_region_tag_redraw(ar);
 			break;
+		case NC_MATERIAL:
+			if (wmn->data == ND_SHADING_LINKS) {
+				SpaceImage *sima = sa->spacedata.first;
+
+				if (sima->flag & SI_TEXPAINT_FILTER_MATERIAL)
+					ED_region_tag_redraw(ar);
+			}
+			break;
 	}
 }
 
diff --git a/source/blender/editors/uvedit/uvedit_draw.c b/source/blender/editors/uvedit/uvedit_draw.c
index 525cedb859f..7b674e75525 100644
--- a/source/blender/editors/uvedit/uvedit_draw.c
+++ b/source/blender/editors/uvedit/uvedit_draw.c
@@ -506,6 +506,8 @@ static void draw_uvs_texpaint(SpaceImage *sima, Scene *scene, Object *ob)
 		mloopuv_base = mloopuv;
 
 		for (a = me->totpoly; a > 0; a--, mpoly++) {
+			if ((sima->flag & SI_TEXPAINT_FILTER_MATERIAL) && mpoly->mat_nr != ob->actcol - 1)
+				continue;
 			glBegin(GL_LINE_LOOP);
 
 			mloopuv = mloopuv_base + mpoly->loopstart;
diff --git a/source/blender/makesdna/DNA_space_types.h b/source/blender/makesdna/DNA_space_types.h
index a267217abf6..41b302ebdd8 100644
--- a/source/blender/makesdna/DNA_space_types.h
+++ b/source/blender/makesdna/DNA_space_types.h
@@ -809,7 +809,9 @@ typedef enum eSpaceImage_Flag {
 
 	SI_COLOR_CORRECTION   = (1 << 24),
 
-	SI_NO_DRAW_TEXPAINT   = (1 << 25)
+	SI_NO_DRAW_TEXPAINT   = (1 << 25),
+	/* filter texpaint uvs based on active material */
+	SI_TEXPAINT_FILTER_MATERIAL   = (1 << 26)
 } eSpaceImage_Flag;
 
 /* Text Editor ============================================ */
diff --git a/source/blender/makesrna/intern/rna_object.c b/source/blender/makesrna/intern/rna_object.c
index 690468a5278..b57c3689d05 100644
--- a/source/blender/makesrna/intern/rna_object.c
+++ b/source/blender/makesrna/intern/rna_object.c
@@ -941,6 +941,7 @@ static void rna_MaterialSlot_name_get(PointerRNA *ptr, char *str)
 static void rna_MaterialSlot_update(Main *bmain, Scene *scene, PointerRNA *ptr)
 {
 	rna_Object_internal_update(bmain, scene, ptr);
+
 	WM_main_add_notifier(NC_OBJECT | ND_OB_SHADING, ptr->id.data);
 	WM_main_add_notifier(NC_MATERIAL | ND_SHADING_LINKS, NULL);
 }
diff --git a/source/blender/makesrna/intern/rna_space.c b/source/blender/makesrna/intern/rna_space.c
index 68173ebefb4..8788a724f0c 100644
--- a/source/blender/makesrna/intern/rna_space.c
+++ b/source/blender/makesrna/intern/rna_space.c
@@ -1523,6 +1523,11 @@ static void rna_def_space_image_uv(BlenderRNA *brna)
 	RNA_def_property_ui_text(prop, "Draw Texture Paint UVs", "Draw overlay of texture paint uv layer");
 	RNA_def_property_update(prop, NC_SPACE | ND_SPACE_IMAGE, NULL);
 
+	prop = RNA_def_property(srna, "texpaint_filter_mat", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_sdna(prop, NULL, "flag", SI_TEXPAINT_FILTER_MATERIAL);
+	RNA_def_property_ui_text(prop, "Same Material UVs", "Only draw UVs of faces with active material");
+	RNA_def_property_update(prop, NC_SPACE | ND_SPACE_IMAGE, NULL);
+
 	prop = RNA_def_property(srna, "show_normalized_coords", PROP_BOOLEAN, PROP_NONE);
 	RNA_def_property_boolean_sdna(prop, NULL, "flag", SI_COORDFLOATS);
 	RNA_def_property_ui_text(prop, "Normalized Coordinates",