In this tutorial, we will see how to use the UV export layout Python function in Blender to export the UV maps (or: layouts) of all the MESH objects available in a scene.
Video Transcript
Hi! In this tutorial, we will see how to use the UV export layout Python function in Blender to export the UV maps (or: layouts) of all the MESH objects available in a scene.
This script can be helpful if you need to provide UV maps as images, such as when publishing your 3D scene on 3D stock websites.
This tutorial was made using Blender 3.3; sometimes, the Blender developers make changes to the Blender Python APIs (BPY for short), but this script should work from version 3 onwards.
The bpy.ops function we are going to use is pretty simple: it only requires two parameters, namely the filepath of the image to be created and the UV size in pixels; however, since we have to use it for all available MESH objects in the scene, we will use a for statement on the MESH objects.
Additionally, I will specify the file extension, which is PNG by default.
Actually, I will export the layouts as PNGs, but I want to show you how to specify it because you can also export the UV layouts as SVG or EPS files.
Okay, let's get started!
Open a BLEND file.
You can start with a brand-new file, too, but you will have to save it somewhere because we will put the PNG files in the same folder as the project.
Let's do some basic imports:
import bpy
from bpy import *
As I said before, the export_layout function requires two parameters, so let's define two variables (we could write the values in the function itself, but I prefer to define them here for clarity's sake):
UVpath = bpy.path.abspath("//") + "UV-LAYOUT---"
UVsize = (2048, 2048)
As you can see, "bpy.path.abspath" will yield the absolute path on disk of the BLEND file. We are going to add a prefix ("UV-LAYOUT---") to all the PNG files, but you can change or remove that.
The UVsize parameter is a tuple of two numerical values, which are the dimensions - in pixels - of the images to be created.
I'm writing 2048, thus creating a 2k image.
In order to execute the function on all the MESH objects available in a scene, we have to create a for statement. So we can write:
for o in bpy.data.objects:
then, inside the block of the for statement (so don't forget to indent the text), we can add a "filter" on the type of the object:
if(o.type=="MESH"):
The condition is clear: the type of the current bpy.data.object must be MESH.
The following statements must be put inside the if, so - again - don't forget to indent the text!
bpy.ops.objects.select_all(action='DESELECT');
we have to do this every time to deselect all the other objects, otherwise we would get an image with two or more UV maps overlapped.
bpy.context.view_layer.objects.active = o
This assignment will set the active object of the scene, assigning the current mesh to context.view_layer.objects.active.
We have to do this because the following OPS (Blender Python operation) will be performed on the one and only active object (remember: you can select multiple objects, but there's only one active object at a time).
bpy.ops.uv.export_layout(filepath = UVpath + o.name, size = UVsize, mode='PNG')
The ops statement will export the layout of the active object to the given filepath (made by the UVpath variable, with the "UV-LAYOUT---" prefix, plus the name of the active object) and with the given size, in pixels.
As I told you before, you can export the UV layouts as PNGs, EPSs, or SVGs. You can specify the output format with the mode parameter, as I just showed.
If we take a look at the output folder, we can see that the script has created as many images as there are meshes.
Since the meshes in my "Desk set 3" 3D model share the same layout with non-overlapping UV islands, I can join all the objects together, run the script again, and get just one non-overlapping UV layout map of the asset.
Before closing this tutorial, I'm going to give you an assignment: edit this script to export both the 2k and 4k UV layouts of the meshes available in your scenes, providing the images with two different prefixes ("UV-2K---" and "UV-4K---," for example).
That's all for this tutorial!
See you soon!