Vertex/Weight Paint: Use PBVH for painting

2016 GSOC project by @nathanvollmer, see D2150

- Mirrored painting and radial symmetry, like in sculpt mode.
- Volume based splash prevention,
  which avoids painting vertices far away from the 3D brush location.
- Normal based splash prevention,
  which avoids painting vertices with normals opposite the normal
  at the 3D brush location.
- Blur mode now uses a nearest neighbor average.
- Average mode, which averages the color/weight
  of the vertices within the brush
- Smudge mode, which pulls the colors/weights
  along the direction of the brush
- RGB^2 color blending, which gives a more accurate
  blend between two colors
- multithreading support. (PBVH leaves are painted in parallel.)
- Foreground/background color picker in vertex paint

release/scripts/startup/bl_ui/space_view3d_toolbar.py

@@ -51,6 +51,19 @@ def draw_keyframing_tools(context, layout):
     row.operator("anim.keyframe_delete_v3d", text="Remove")
 
 
+# Used by vertex & weight paint
+def draw_vpaint_symmetry(layout, vpaint):
+    col = layout.column(align=True)
+    col.label(text="Mirror:")
+    row = col.row(align=True)
+
+    row.prop(vpaint, "use_symmetry_x", text="X", toggle=True)
+    row.prop(vpaint, "use_symmetry_y", text="Y", toggle=True)
+    row.prop(vpaint, "use_symmetry_z", text="Z", toggle=True)
+
+    col = layout.column()
+    col.prop(vpaint, "radial_symmetry", text="Radial")
+
 # ********** default tools for object-mode ****************
 
 
@@ -1134,7 +1147,11 @@ class VIEW3D_PT_tools_brush(Panel, View3DPaintPanel):
             self.prop_unified_color_picker(col, context, brush, "color", value_slider=True)
             if settings.palette:
                 col.template_palette(settings, "palette", color=True)
-            self.prop_unified_color(col, context, brush, "color", text="")
+            row = col.row(align=True)
+            self.prop_unified_color(row, context, brush, "color", text="")
+            self.prop_unified_color(row, context, brush, "secondary_color", text="")
+            row.separator()
+            row.operator("paint.brush_colors_flip", icon='FILE_REFRESH', text="")
 
             col.separator()
             row = col.row(align=True)
@@ -1717,6 +1734,19 @@ class VIEW3D_PT_tools_weightpaint(View3DPanel, Panel):
         props.data_type = 'VGROUP_WEIGHTS'
 
 
+class VIEW3D_PT_tools_weightpaint_symmetry(Panel, View3DPaintPanel):
+    bl_category = "Tools"
+    bl_context = "weightpaint"
+    bl_options = {'DEFAULT_CLOSED'}
+    bl_label = "Symmetry"
+
+    def draw(self, context):
+        layout = self.layout
+        toolsettings = context.tool_settings
+        wpaint = toolsettings.weight_paint
+        draw_vpaint_symmetry(layout, wpaint)
+
+
 class VIEW3D_PT_tools_weightpaint_options(Panel, View3DPaintPanel):
     bl_category = "Options"
     bl_context = "weightpaint"
@@ -1779,6 +1809,20 @@ class VIEW3D_PT_tools_vertexpaint(Panel, View3DPaintPanel):
 #~         col.label(text="Multiply:")
 #~         col.prop(vpaint, "mul", text="")
 
+
+class VIEW3D_PT_tools_vertexpaint_symmetry(Panel, View3DPaintPanel):
+    bl_category = "Tools"
+    bl_context = "vertexpaint"
+    bl_options = {'DEFAULT_CLOSED'}
+    bl_label = "Symmetry"
+
+    def draw(self, context):
+        layout = self.layout
+        toolsettings = context.tool_settings
+        vpaint = toolsettings.vertex_paint
+        draw_vpaint_symmetry(layout, vpaint)
+
+
 # ********** default tools for texture-paint ****************
 
 
@@ -2058,8 +2102,10 @@ classes = (
     VIEW3D_PT_sculpt_symmetry,
     VIEW3D_PT_tools_brush_appearance,
     VIEW3D_PT_tools_weightpaint,
+    VIEW3D_PT_tools_weightpaint_symmetry,
     VIEW3D_PT_tools_weightpaint_options,
     VIEW3D_PT_tools_vertexpaint,
+    VIEW3D_PT_tools_vertexpaint_symmetry,
     VIEW3D_PT_tools_imagepaint_external,
     VIEW3D_PT_tools_imagepaint_symmetry,
     VIEW3D_PT_tools_projectpaint,