How to convert UV to mesh in blender?

Question

well i know about export svg , but i want to know how to use UV as a mesh then use it for shape key ? because vertex ids change after export and import svg , and can't be used for shape key , (For unfolding a mesh ) , is there any addon to do that ?

Answer 1

(See Update below for Blender 3.0b)

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Nowadays, this is quite simple with Geometry Nodes:

To separate any UV islands, duplicating seam vertices, you can split the edges first, and then re-weld them:

For this kind of transition, when you take the modifier's 'Fac' from 0 to 1:

If you would prefer to animate the transition with shape-keys, you could apply the modifiers at the start and end states on copies of your object, without the Weld, to maintain the vertex-count and order.

Then you can 'Join as Shapes' the copies, and edit other in-between keys as you wish. You would have to take care not to separate vertices which are not on seams, but seam verts and non-seam verts could be stashed as vertex groups, to make selection easier.

Update: Blender3.0b

In Geometry Nodes (Fields) the tree can be something more along these lines:

• Access to the UV Map is now through the modifier's interface
• Edges can be split inside the node tree
• .. and in 3.0+, re-welded with Geometry > Merge by Distance

Answer 2

To make a UV map mesh from a mesh's UVs

Nostalgic method, via some scripting

Suzanne transforming to her UVs

Using code from Exporting UV Layout with only outlines (similarly to Blender python trying to scale the uv and How to get data and edit it on UV map edges? )

can make a "UV mesh" in the $XY$ plane using the UV coordinates of the active UV map.

import bpy
import numpy as np

ob = bpy.context.object
me = ob.data
uv_layer = me.uv_layers.active
# get uv values
uvs = np.empty((2 * len(me.loops), 1))
uv_layer.data.foreach_get("uv", uvs)
x, y = uvs.reshape((-1, 2)).T

z = np.zeros((len(x)))

uvme = bpy.data.meshes.new("UVMesh")
verts = np.array((x, y, z)).T
#verts -= (0.5, 0.5, 0)
faces = [p.loop_indices for p in me.polygons]

uvme.from_pydata(
        verts,
        [],
        faces
        )

bpy.context.collection.objects.link(bpy.data.objects.new("UVMesh", uvme))

A matching face loop mesh

Equivalent of splitting all edges, to create a mesh from original with no connected faces (to match the UV loops)

import bpy
import numpy as np

ob = bpy.context.object
me = ob.data
coords = np.empty(3 * len(me.vertices))
me.vertices.foreach_get("co", coords)

idxs = np.empty(len(me.loops), dtype=int)
me.loops.foreach_get("vertex_index", idxs)


uvme = bpy.data.meshes.new("UVMesh")
verts = coords.reshape((-1, 3))

faces = [p.loop_indices for p in me.polygons]

uvme.from_pydata(
        verts[idxs],
        [],
        faces
        )

bpy.context.collection.objects.link(bpy.data.objects.new("UVMesh", uvme))

Join as Shapes.

Since the results of running both scripts above will have the same face and vertex counts they can be joined as shapes. To get a similar result shown as obtained by RobinBetts move the origin of UV to (0.5, 0.5, 0) and scale by 2.74 before joining.

Answer 3

Update for Blender 3.2:

Named Attributes are back! It's even easier now:

You can also use the new Merge By Distance node to join the faces together again.

Answer 4

You can use the Wrap Tools addon by Rich Colburn, video here:

• Create your object, rip it (V) along the seam you want to create, open the N panel > Extended Tools, click on Create UV Shape, it will create a shape key for this object:

• Back to Object mode, go into the Shape Key panel, select the second one and put the Value to 1 to "unwrap" the object. If you want to stick an object on the surface, create it, then select it, shift select your first object and press on Bind to Surface then Scene Update:

To bring back the object to its original shape, bring back the shape key Value to 0, the other object will follow:

Answer 5

Geometry Nodes for this are great, but they don't allow you to work on the mesh, because Geo Nodes are seen as a modifier.

If you want to be able to work on the unwrapped mesh, use TexTools:

https://github.com/SavMartin/TexTools-Blender/releases/tag/v1.5

In the UV editor, there's a Mesh UV Tools section and a button for Create UV Mesh. This will create a new mesh that has a shape key already in it. Set the shape key to 0 and you get your original mesh. Set it to 1 and you get the UV.