Fix #28347: VBO's highlights wrong faces when Mirror modifier is in use

Added callback to drawMappedFaces which checks if two faces have got equal draw options.

After discussion with Brecht we found it's nicest solution for now:
- Disabling VBOs in edit mode for this case wouldn't be nicer for this case -
  some additional flag stored in DM should be added in this case.
- Adding new callback in DM isn't nicer that this solution.
- Handling face selection in drawobject would lead to duplicated code
  which is also not nice.

Hopefully, this callback could handle all cases in the future.

Also, Brecht mentioned current VBO implementation isn't perfect, so maybe
when we'll redesign this area dealing with edit mode wouldn't be so tricky.

2 files changed, 34 insertions, 12 deletions

diff --git a/source/blender/editors/space_view3d/drawmesh.c b/source/blender/editors/space_view3d/drawmesh.c
index 71c85483244..6e02ecbd5a8 100644
--- a/source/blender/editors/space_view3d/drawmesh.c
+++ b/source/blender/editors/space_view3d/drawmesh.c
@@ -607,7 +607,7 @@ void draw_mesh_textured(Scene *scene, View3D *v3d, RegionView3D *rv3d, Object *o
 	}
 	else if(faceselect) {
 		if(ob->mode & OB_MODE_WEIGHT_PAINT)
-			dm->drawMappedFaces(dm, wpaint__setSolidDrawOptions, me, 1, GPU_enable_material);
+			dm->drawMappedFaces(dm, wpaint__setSolidDrawOptions, me, 1, GPU_enable_material, NULL);
 		else
 			dm->drawMappedFacesTex(dm, me->mface ? draw_tface_mapped__set_draw : NULL, me);
 	}
diff --git a/source/blender/editors/space_view3d/drawobject.c b/source/blender/editors/space_view3d/drawobject.c
index 638d197ccf7..8ca352ffe42 100644
--- a/source/blender/editors/space_view3d/drawobject.c
+++ b/source/blender/editors/space_view3d/drawobject.c
@@ -2030,6 +2030,28 @@ static int draw_dm_faces_sel__setDrawOptions(void *userData, int index, int *UNU
 	return 0;
 }
 
+static int draw_dm_faces_sel__compareDrawOptions(void *userData, int index, int next_index)
+{
+	struct { unsigned char *cols[3]; EditFace *efa_act; } * data = userData;
+	EditFace *efa = EM_get_face_for_index(index);
+	EditFace *next_efa = EM_get_face_for_index(next_index);
+	unsigned char *col, *next_col;
+
+	if(efa == next_efa)
+		return 1;
+
+	if(efa == data->efa_act || next_efa == data->efa_act)
+		return 0;
+
+	col = data->cols[(efa->f&SELECT)?1:0];
+	next_col = data->cols[(next_efa->f&SELECT)?1:0];
+
+	if(col[3]==0 || next_col[3]==0)
+		return 0;
+
+	return col == next_col;
+}
+
 /* also draws the active face */
 static void draw_dm_faces_sel(DerivedMesh *dm, unsigned char *baseCol, unsigned char *selCol, unsigned char *actCol, EditFace *efa_act) 
 {
@@ -2039,7 +2061,7 @@ static void draw_dm_faces_sel(DerivedMesh *dm, unsigned char *baseCol, unsigned
 	data.cols[2] = actCol;
 	data.efa_act = efa_act;
 
-	dm->drawMappedFaces(dm, draw_dm_faces_sel__setDrawOptions, &data, 0, GPU_enable_material);
+	dm->drawMappedFaces(dm, draw_dm_faces_sel__setDrawOptions, &data, 0, GPU_enable_material, draw_dm_faces_sel__compareDrawOptions);
 }
 
 static int draw_dm_creases__setDrawOptions(void *UNUSED(userData), int index)
@@ -2449,7 +2471,7 @@ static void draw_em_fancy(Scene *scene, View3D *v3d, RegionView3D *rv3d, Object
 			glEnable(GL_LIGHTING);
 			glFrontFace((ob->transflag&OB_NEG_SCALE)?GL_CW:GL_CCW);
 
-			finalDM->drawMappedFaces(finalDM, draw_em_fancy__setFaceOpts, NULL, 0, GPU_enable_material);
+			finalDM->drawMappedFaces(finalDM, draw_em_fancy__setFaceOpts, NULL, 0, GPU_enable_material, NULL);
 
 			glFrontFace(GL_CCW);
 			glDisable(GL_LIGHTING);
@@ -2678,7 +2700,7 @@ static void draw_mesh_fancy(Scene *scene, ARegion *ar, View3D *v3d, RegionView3D
 			/* weight paint in solid mode, special case. focus on making the weights clear
 			 * rather than the shading, this is also forced in wire view */
 			GPU_enable_material(0, NULL);
-			dm->drawMappedFaces(dm, wpaint__setSolidDrawOptions, me->mface, 1, GPU_enable_material);
+			dm->drawMappedFaces(dm, wpaint__setSolidDrawOptions, me->mface, 1, GPU_enable_material, NULL);
 		
 			bglPolygonOffset(rv3d->dist, 1.0);
 			glDepthMask(0);	// disable write in zbuffer, selected edge wires show better
@@ -2758,7 +2780,7 @@ static void draw_mesh_fancy(Scene *scene, ARegion *ar, View3D *v3d, RegionView3D
 				glEnable(GL_LIGHTING);
 				glEnable(GL_COLOR_MATERIAL);
 
-				dm->drawMappedFaces(dm, wpaint__setSolidDrawOptions, me->mface, 1, GPU_enable_material);
+				dm->drawMappedFaces(dm, wpaint__setSolidDrawOptions, me->mface, 1, GPU_enable_material, NULL);
 				glDisable(GL_COLOR_MATERIAL);
 				glDisable(GL_LIGHTING);
 
@@ -2766,10 +2788,10 @@ static void draw_mesh_fancy(Scene *scene, ARegion *ar, View3D *v3d, RegionView3D
 			}
 			else if(ob->mode & (OB_MODE_VERTEX_PAINT|OB_MODE_TEXTURE_PAINT)) {
 				if(me->mcol)
-					dm->drawMappedFaces(dm, wpaint__setSolidDrawOptions, NULL, 1, GPU_enable_material);
+					dm->drawMappedFaces(dm, wpaint__setSolidDrawOptions, NULL, 1, GPU_enable_material, NULL);
 				else {
 					glColor3f(1.0f, 1.0f, 1.0f);
-					dm->drawMappedFaces(dm, wpaint__setSolidDrawOptions, NULL, 0, GPU_enable_material);
+					dm->drawMappedFaces(dm, wpaint__setSolidDrawOptions, NULL, 0, GPU_enable_material, NULL);
 				}
 			}
 		}
@@ -6459,7 +6481,7 @@ static void bbs_mesh_solid_EM(Scene *scene, View3D *v3d, Object *ob, DerivedMesh
 	cpack(0);
 
 	if (facecol) {
-		dm->drawMappedFaces(dm, bbs_mesh_solid__setSolidDrawOptions, (void*)(intptr_t) 1, 0, GPU_enable_material);
+		dm->drawMappedFaces(dm, bbs_mesh_solid__setSolidDrawOptions, (void*)(intptr_t) 1, 0, GPU_enable_material, NULL);
 
 		if(check_ob_drawface_dot(scene, v3d, ob->dt)) {
 			glPointSize(UI_GetThemeValuef(TH_FACEDOT_SIZE));
@@ -6470,7 +6492,7 @@ static void bbs_mesh_solid_EM(Scene *scene, View3D *v3d, Object *ob, DerivedMesh
 		}
 
 	} else {
-		dm->drawMappedFaces(dm, bbs_mesh_solid__setSolidDrawOptions, (void*) 0, 0, GPU_enable_material);
+		dm->drawMappedFaces(dm, bbs_mesh_solid__setSolidDrawOptions, (void*) 0, 0, GPU_enable_material, NULL);
 	}
 }
 
@@ -6499,8 +6521,8 @@ static void bbs_mesh_solid(Scene *scene, Object *ob)
 	
 	glColor3ub(0, 0, 0);
 		
-	if((me->editflag & ME_EDIT_PAINT_MASK))	dm->drawMappedFaces(dm, bbs_mesh_solid_hide__setDrawOpts, me, 0, GPU_enable_material);
-	else									dm->drawMappedFaces(dm, bbs_mesh_solid__setDrawOpts, me, 0, GPU_enable_material);
+	if((me->editflag & ME_EDIT_PAINT_MASK))	dm->drawMappedFaces(dm, bbs_mesh_solid_hide__setDrawOpts, me, 0, GPU_enable_material, NULL);
+	else									dm->drawMappedFaces(dm, bbs_mesh_solid__setDrawOpts, me, 0, GPU_enable_material, NULL);
 
 	dm->release(dm);
 }
@@ -6607,7 +6629,7 @@ static void draw_object_mesh_instance(Scene *scene, View3D *v3d, RegionView3D *r
 			GPU_end_object_materials();
 		}
 		else if(edm)
-			edm->drawMappedFaces(edm, NULL, NULL, 0, GPU_enable_material);
+			edm->drawMappedFaces(edm, NULL, NULL, 0, GPU_enable_material, NULL);
 		
 		glDisable(GL_LIGHTING);
 	}