Select By Color (Blender)

select_by_color.py

import bpy
from mathutils import Color

bl_info = {
    'name': 'Select By Color',
    'author': 'Tamas Kemenczy',
    'version': (0, 1),
    'blender': (2, 6, 1),
    'location': 'View3D > Specials > Select By Color',
    'description': 'Select all faces with the same vertex color of the selected face',
    'category': 'Mesh'
}

def select_by_color(obj, threshold=0.01):
    # get wierd behavior/errors when in editmode
    bpy.ops.object.editmode_toggle()

    colors = obj.data.vertex_colors.active.data
    selected_polygons = list(filter(lambda p: p.select, obj.data.polygons))

    if len(selected_polygons):
        p = selected_polygons[0]
        r = g = b = 0
        for i in p.loop_indices:
            c = colors[i].color
            r += c.r
            g += c.g
            b += c.b
        r /= p.loop_total
        g /= p.loop_total
        b /= p.loop_total
        target = Color((r, g, b))

        for p in obj.data.polygons:
            r = g = b = 0
            for i in p.loop_indices:
                c = colors[i].color
                r += c.r
                g += c.g
                b += c.b
            r /= p.loop_total
            g /= p.loop_total
            b /= p.loop_total
            source = Color((r, g, b))

            print(target, source)

            if (abs(source.r - target.r) < threshold and
                abs(source.g - target.g) < threshold and
                abs(source.b - target.b) < threshold):

                p.select = True

    bpy.ops.object.editmode_toggle()

class SelectByColor(bpy.types.Operator):
    bl_idname = 'mesh.select_by_color'
    bl_label = 'Select By Color'
    bl_options = {'REGISTER', 'UNDO'}

    threshold = bpy.props.FloatProperty(name='Threshold', default=0.01, min=0.001, max=1.0, step=1)

    @classmethod
    def poll(cls, context):
        obj = context.active_object
        return (obj and obj.type == 'MESH')

    def execute(self, context):
        select_by_color(context.active_object, self.threshold)
        return {'FINISHED'}

def menu_func(self, context):
    self.layout.operator(SelectByColor.bl_idname, text='Select By Color')

def register():
    bpy.utils.register_module(__name__)
    bpy.types.VIEW3D_MT_edit_mesh_specials.append(menu_func)

def unregister():
    bpy.utils.unregister_module(__name__)
    bpy.types.VIEW3D_MT_edit_mesh_specials.remove(menu_func)

if __name__ == "__main__":
    register()

Great tool! Excactly what I was looking for, thanks a lot!!!

Works with .ply imported from magicavoxel.

What license is this under? I'd like to use it while manipulating commercial assets

Edit: Never mind, I just read on the Blender.org FAQ that python plugins that use the Blender API are part of the same license as Blender (GNU GPL). Commented for anybody else who might be interested.

how do you use this?