op_color_from_elements.py

import bpy
import bmesh
import operator
from mathutils import Vector
from collections import defaultdict
from math import pi

from . import utilities_color

class op(bpy.types.Operator):
    bl_idname = "uv.textools_color_from_elements"
    bl_label = "Color Elements"
    bl_description = "Assign a color ID to each mesh element"
    bl_options = {'REGISTER', 'UNDO'}
    

    @classmethod
    def poll(cls, context):
        if not bpy.context.active_object:
            return False

        if bpy.context.active_object not in bpy.context.selected_objects:
            return False

        if len(bpy.context.selected_objects) != 1:
            return False

        if bpy.context.active_object.type != 'MESH':
            return False

        #Only in UV editor mode
        if bpy.context.area.type != 'IMAGE_EDITOR':
            return False

        return True
    
    def execute(self, context):
        color_elements(self, context)
        return {'FINISHED'}



def color_elements(self, context):
    obj = bpy.context.active_object
    
    # Setup Edit & Face mode
    if obj.mode != 'EDIT':
        bpy.ops.object.mode_set(mode='EDIT')
    bpy.ops.mesh.select_mode(use_extend=False, use_expand=False, type='FACE')
    
    # Collect groups
    bm = bmesh.from_edit_mesh(bpy.context.active_object.data);
    faces_indices_processed = []
    groups = []

    for face in bm.faces:
        if face.index not in faces_indices_processed:
            # Select face & extend
            bpy.ops.mesh.select_all(action='DESELECT')
            face.select = True
            bpy.ops.mesh.select_linked(delimit={'NORMAL'})

            faces = [f.index for f in bm.faces if (f.select and f.index not in faces_indices_processed)]
            for f in faces:
                faces_indices_processed.append(f)
            groups.append(faces)

    
    # Assign color count (caps automatically e.g. max 20)
    bpy.context.scene.texToolsSettings.color_ID_count = len(groups)
    gamma = 2.2

    for i in range(bpy.context.scene.texToolsSettings.color_ID_count):
        color = utilities_color.get_color_id(i, bpy.context.scene.texToolsSettings.color_ID_count)
        # Fix Gamma
        color[0] = pow(color[0] , gamma)
        color[1] = pow(color[1] , gamma)
        color[2] = pow(color[2], gamma)
        utilities_color.set_color(i, color)

    # Assign Groups to colors
    index_color = 0
    for group in groups:
        # rebuild bmesh data (e.g. left edit mode previous loop)
        bm = bmesh.from_edit_mesh(bpy.context.active_object.data);
        if hasattr(bm.faces, "ensure_lookup_table"): 
            bm.faces.ensure_lookup_table()

        # Select group
        bpy.ops.mesh.select_all(action='DESELECT')
        for index_face in group:
            bm.faces[index_face].select = True

        # Assign to selection
        bpy.ops.uv.textools_color_assign(index=index_color)

        index_color = (index_color+1) % bpy.context.scene.texToolsSettings.color_ID_count

    bpy.ops.object.mode_set(mode='OBJECT')
    utilities_color.validate_face_colors(obj)

bpy.utils.register_class(op)