Changing Order of UV Maps

Question

For my mesh I have two UV Maps. I'm importing the Blender file into an external program which requires the UVMaps to be in a certain order. In the UV Maps list there are no up/down arrows like there is in the Vertex Groups list to change the order of elements in the list. Is there a way to assign the order of UV Maps in Blender? Or could there be a Python script to do this?

Answer 1

Here is an add-on that does what Stefan Schindler mentioned (I can't say I didn't already know that trick, but he did mention it before I did...). I would recommend that you check it out at the GitHub page here so that you know that you have the most up-to-date version. It is also just fine to use this link if you'd prefer to copy/paste rather than download and unzip it.

Here is the original version of the code though (like I said, it is preferable to get a copy from GitHub because I won't be updating this).

# Copyright 2016 Jake Dube
#
# ### BEGIN GPL LICENSE BLOCK ###
#
# 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 3 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, see <http://www.gnu.org/licenses/>.
#
# ### END GPL LICENSE BLOCK ###

import bpy
from bpy.types import Operator

bl_info = {
    "name": "UV Tools",
    "author": "Jake Dube",
    "version": (1, 0),
    "blender": (2, 77, 0),
    "location": "UV maps in properties window",
    "description": "Some tools for uv maps that should already be in Blender.",
    "category": "UV"}


def make_active(name):
    uvs = bpy.context.scene.objects.active.data.uv_textures
    for uv in uvs:
        if uv.name == name:
            uvs.active = uv
            return
    print("Could not find:", name, "\n(this should never happen)")


def move_to_bottom(index):
    uvs = bpy.context.scene.objects.active.data.uv_textures
    uvs.active_index = index
    new_name = uvs.active.name

    bpy.ops.mesh.uv_texture_add()

    # delete the "old" one
    make_active(new_name)
    bpy.ops.mesh.uv_texture_remove()

    # set the name of the last one
    uvs.active_index = len(uvs) - 1
    uvs.active.name = new_name


class MoveUVMapDown(Operator):
    bl_idname = "uv_tools.move_uvmap_down"
    bl_label = "Move Down"
    bl_options = {"REGISTER", "UNDO"}

    def execute(self, context):
        uvs = context.scene.objects.active.data.uv_textures

        # get the selected UV map
        orig_ind = uvs.active_index
        orig_name = uvs.active.name

        if orig_ind == len(uvs) - 1:
            return {'FINISHED'}

        # use "trick" on the one after it
        move_to_bottom(orig_ind + 1)

        # use the "trick" on the UV map
        move_to_bottom(orig_ind)

        # use the "trick" on the rest that are after where it was
        for i in range(orig_ind, len(uvs) - 2):
            move_to_bottom(orig_ind)

        make_active(orig_name)

        return {'FINISHED'}


class MoveUVMapUp(Operator):
    bl_idname = "uv_tools.move_uvmap_up"
    bl_label = "Move Up"
    bl_options = {"REGISTER", "UNDO"}

    def execute(self, context):
        uvs = context.scene.objects.active.data.uv_textures

        if uvs.active_index == 0:
            return {'FINISHED'}

        original = uvs.active.name
        uvs.active_index -= 1
        bpy.ops.uv_tools.move_uvmap_down()
        make_active(original)

        return {'FINISHED'}


def uv_tools_addition(self, context):
    layout = self.layout
    col = layout.column(align=True)
    col.operator("uv_tools.move_uvmap_up", icon='TRIA_UP')
    col.operator("uv_tools.move_uvmap_down", icon='TRIA_DOWN')


def register():
    bpy.utils.register_class(MoveUVMapDown)
    bpy.utils.register_class(MoveUVMapUp)
    bpy.types.DATA_PT_uv_texture.append(uv_tools_addition)


def unregister():
    bpy.utils.unregister_class(MoveUVMapDown)
    bpy.utils.unregister_class(MoveUVMapUp)
    bpy.types.DATA_PT_uv_texture.remove(uv_tools_addition)


if __name__ == "__main__":
    register()

This add-on (at the time of this writing) simply adds two buttons below the uv maps list like this:

Answer 2

There is a little trick to it. When you have selected one UV Map and hit the plus button it duplicates the currently selected UV Map and puts it at the end.

So here are steps needed in order to reorder the order of UV Maps :

1. Select the first UV Map.
2. Click on the Plus button.
3. Delete the first UV map.
4. Rename the last UV Map to not contain the .001 suffix.

Answer 3

Modified for 2.8

import bpy
from bpy.types import Operator

bl_info = {
    "name": "UV Tools",
    "author": "Jake Dube (modified by Denis Khomenko for 2.8)",
    "version": (1, 0),
    "blender": (2, 80, 75),
    "location": "UV maps in properties window",
    "description": "Some tools for uv maps that should already be in Blender.",
    "category": "UV"}


def make_active(name):
    uvs = bpy.context.active_object.data.uv_layers  #bpy.context.scene.objects.active.data.uv_textures
    for uv in uvs:
        if uv.name == name:
            uvs.active = uv
            return
    print("Could not find:", name, "\n(this should never happen)")


def move_to_bottom(index):
    uvs = bpy.context.active_object.data.uv_layers #bpy.context.scene.objects.active.data.uv_textur
    uvs.active_index = index
    new_name = uvs.active.name

    bpy.ops.mesh.uv_texture_add()

    # delete the "old" one
    make_active(new_name)
    bpy.ops.mesh.uv_texture_remove()

    # set the name of the last one
    uvs.active_index = len(uvs) - 1
    uvs.active.name = new_name


class MoveUVMapDown(Operator):
    bl_idname = "uv_tools.move_uvmap_down"
    bl_label = "Move Down"
    bl_options = {"REGISTER", "UNDO"}

    def execute(self, context):
        uvs = bpy.context.active_object.data.uv_layers #context.scene.objects.active.data.uv_textures

        # get the selected UV map
        orig_ind = uvs.active_index
        orig_name = uvs.active.name

        if orig_ind == len(uvs) - 1:
            return {'FINISHED'}

        # use "trick" on the one after it
        move_to_bottom(orig_ind + 1)

        # use the "trick" on the UV map
        move_to_bottom(orig_ind)

        # use the "trick" on the rest that are after where it was
        for i in range(orig_ind, len(uvs) - 2):
            move_to_bottom(orig_ind)

        make_active(orig_name)

        return {'FINISHED'}


class MoveUVMapUp(Operator):
    bl_idname = "uv_tools.move_uvmap_up"
    bl_label = "Move Up"
    bl_options = {"REGISTER", "UNDO"}

    def execute(self, context):
        uvs = bpy.context.active_object.data.uv_layers  #context.scene.objects.active.data.uv_textures

        if uvs.active_index == 0:
            return {'FINISHED'}

        original = uvs.active.name
        uvs.active_index -= 1
        bpy.ops.uv_tools.move_uvmap_down()
        make_active(original)

        return {'FINISHED'}


def uv_tools_addition(self, context):
    layout = self.layout
    col = layout.column(align=True)
    col.operator("uv_tools.move_uvmap_up", icon='TRIA_UP')
    col.operator("uv_tools.move_uvmap_down", icon='TRIA_DOWN')


def register():
    bpy.utils.register_class(MoveUVMapDown)
    bpy.utils.register_class(MoveUVMapUp)
    bpy.types.DATA_PT_uv_texture.append(uv_tools_addition)


def unregister():
    bpy.utils.unregister_class(MoveUVMapDown)
    bpy.utils.unregister_class(MoveUVMapUp)
    bpy.types.DATA_PT_uv_texture.remove(uv_tools_addition)


if __name__ == "__main__":
    register()

Answer 4

Another variation with options to sort UVs by name

# ### BEGIN GPL LICENSE BLOCK ###
#
# 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 3 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, see <http://www.gnu.org/licenses/>.
#
# ### END GPL LICENSE BLOCK ###

import bpy
from bpy.types import Operator

bl_info = {
    "name": "UV List Tools",
    "author": "Jake Dube, cdeguise, bovesan, APEC",
    "version": (1, 1),
    "blender": (2, 80, 0),
    "location": "UV maps in properties window",
    "description": "Some tools for uv maps that should already be in Blender.",
    "doc_url": "",
    "tracker_url": "",
    "category": "UV"
}


def make_active(name):
    uvs = bpy.context.view_layer.objects.active.data.uv_layers
    for uv in uvs:
        if uv.name == name:
            uvs.active = uv
            return
    print("Could not find:", name, "\n(this should never happen)")


def move_to_bottom(index):
    uvs = bpy.context.view_layer.objects.active.data.uv_layers
    uvs.active_index = index
    new_name = uvs.active.name

    bpy.ops.mesh.uv_texture_add()

    # delete the "old" one
    make_active(new_name)
    bpy.ops.mesh.uv_texture_remove()

    # set the name of the last one
    uvs.active_index = len(uvs) - 1
    uvs.active.name = new_name


class MESH_OT_uv_down(Operator):
    bl_idname = "mesh.uv_texture_down"
    bl_label = "Move Down"
    bl_options = {"REGISTER", "UNDO"}

    def execute(self, context):
        uvs = context.view_layer.objects.active.data.uv_layers

        # get the selected UV map
        orig_ind = uvs.active_index
        orig_name = uvs.active.name

        if orig_ind == len(uvs) - 1:
            return {'FINISHED'}

        # use "trick" on the one after it
        move_to_bottom(orig_ind + 1)

        # use the "trick" on the UV map
        move_to_bottom(orig_ind)

        # use the "trick" on the rest that are after where it was
        for i in range(orig_ind, len(uvs) - 2):
            move_to_bottom(orig_ind)

        make_active(orig_name)

        return {'FINISHED'}


class MESH_OT_uv_up(Operator):
    bl_idname = "mesh.uv_texture_up"
    bl_label = "Move Up"
    bl_options = {"REGISTER", "UNDO"}

    def execute(self, context):
        uvs = bpy.context.view_layer.objects.active.data.uv_layers

        if uvs.active_index == 0:
            return {'FINISHED'}

        original = uvs.active.name
        uvs.active_index -= 1
        bpy.ops.mesh.uv_texture_down()
        make_active(original)

        return {'FINISHED'}


class MESH_OT_uv_a_to_z (Operator):
    bl_idname = 'mesh.uv_texture_a_to_z'
    bl_label = 'Sort A to Z'
    bl_description = "Sorting UVs by name (A to Z)"
    bl_options = {"REGISTER", "UNDO"}
  
    def execute(self, context):        
        uvs = context.view_layer.objects.active.data.uv_layers
        orig_name = uvs.active.name
        
        for j in range (len(uvs)):
            for i in range (len(uvs)-1):
                uvs.active_index = i
                temp_name = uvs.active.name
                uvs.active_index = i+1
                if uvs.active.name < temp_name:
                    bpy.ops.mesh.uv_texture_up()
                    
        make_active(orig_name)
                    
        return {"FINISHED"}
        
    
class MESH_OT_uv_z_to_a (Operator):
    bl_idname = 'mesh.uv_texture_z_to_a'
    bl_label = 'Sort Z to A'
    bl_description = "Sorting UVs by name (Z to A)"
    bl_options = {"REGISTER", "UNDO"}
  
    def execute(self, context):
        uvs = context.view_layer.objects.active.data.uv_layers
        orig_name = uvs.active.name
         
        for j in range (len(uvs)):
            for i in range (len(uvs)-1):
                uvs.active_index = i+1
                temp_name = uvs.active.name
                uvs.active_index = i
                if uvs.active.name < temp_name:
                    bpy.ops.mesh.uv_texture_down()
        
        make_active(orig_name)
                    
        return {"FINISHED"}


def uv_tools_addition(self, context):
    layout = self.layout      
    layout.label(text="Active object UV Tools:")
    row = layout.row()
    
    col1 = row.column(align=True)
    col1.operator("mesh.uv_texture_up", icon='TRIA_UP')
    col1.operator("mesh.uv_texture_down", icon='TRIA_DOWN')
    
    layout.separator()   
     
    col2 = row.column(align=True)
    col2.operator("mesh.uv_texture_a_to_z", icon='TRIA_UP_BAR')
    col2.operator("mesh.uv_texture_z_to_a", icon='TRIA_DOWN_BAR')


def register():
    bpy.utils.register_class(MESH_OT_uv_down)
    bpy.utils.register_class(MESH_OT_uv_up)
    bpy.utils.register_class(MESH_OT_uv_a_to_z)
    bpy.utils.register_class(MESH_OT_uv_z_to_a)
    bpy.types.DATA_PT_uv_texture.append(uv_tools_addition)


def unregister():
    bpy.utils.unregister_class(MESH_OT_uv_down)
    bpy.utils.unregister_class(MESH_OT_uv_up)
    bpy.utils.unregister_class(MESH_OT_uv_a_to_z)
    bpy.utils.unregister_class(MESH_OT_uv_z_to_a)
    bpy.types.DATA_PT_uv_texture.remove(uv_tools_addition)


if __name__ == "__main__":
    register()