small add-on to calculate face areas as vertex colors

Author: varkenvarken

facearea.py

@@ -0,0 +1,96 @@
+# ##### BEGIN GPL LICENSE BLOCK #####
+#
+#  facearea.py , a Blender addon to calculate vertex colors based on face area.
+#  (c) 2020 Michel J. Anders (varkenvarken)
+#
+#  This program is free software; you can redistribute it and/or
+#  modify it under the terms of the GNU General Public License
+#  as published by the Free Software Foundation; either version 2
+#  of the License, or (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software Foundation,
+#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+# ##### END GPL LICENSE BLOCK #####
+
+bl_info = {
+	"name": "facearea",
+	"author": "Michel Anders (varkenvarken)",
+	"version": (0, 0, 202005101258),
+	"blender": (2, 83, 0),
+	"location": "View3D > Vertex Paint > Weights > WeightLifter",
+	"description": "",
+	"warning": "",
+	"wiki_url": "",
+	"category": "Paint"}
+
+import numpy as np
+import bpy
+import bmesh
+
+
+class FaceArea(bpy.types.Operator):
+	bl_idname = "paint.facearea"
+	bl_label = "Face Area"
+	bl_description = "Calculate vertex colors based on face area"
+	bl_options = {'REGISTER', 'UNDO'}
+
+
+	@classmethod
+	def poll(self, context):
+		"""
+		Only visible in vertex paint mode if the active object is a mesh and has at least one vertex color layer
+		"""
+		p = (context.mode == 'PAINT_VERTEX' and
+			isinstance(context.object, bpy.types.Object) and
+			isinstance(context.object.data, bpy.types.Mesh) and
+			len(context.object.data.vertex_colors)
+			)
+		return p
+
+	def execute(self, context):
+		bpy.ops.object.mode_set(mode='OBJECT')
+
+		scene = context.scene
+		self.ob = context.active_object
+		mesh = context.object.data
+
+		vertex_colors = mesh.vertex_colors.active.data
+
+		areamap = {loop:f.area for f in mesh.polygons for loop in range(f.loop_start, f.loop_start + f.loop_total)}
+		maxarea = max(areamap.values())
+		print(maxarea)
+		for i,area in areamap.items():
+			w=area/maxarea
+			vertex_colors[i].color[:3] = (w,w,w)
+
+		bpy.ops.object.mode_set(mode='VERTEX_PAINT')
+		bpy.ops.object.mode_set(mode='EDIT')
+		bpy.ops.object.mode_set(mode='VERTEX_PAINT')
+
+		return {'FINISHED'}
+
+
+def menu_func_vcol(self, context):
+	self.layout.operator(FaceArea.bl_idname,icon='PLUGIN')
+
+classes = (FaceArea, )
+
+register_classes, unregister_classes = bpy.utils.register_classes_factory(classes)
+
+def register():
+	register_classes()
+	bpy.types.VIEW3D_MT_paint_vertex.append(menu_func_vcol)
+
+def unregister():
+	bpy.types.VIEW3D_MT_paint_vertex.remove(menu_func_vcol)
+	unregister_classes()
+
+if __name__ == "__main__":
+	register()