Disjoint mapping mesh question

Hi @Jussi_Aaltonen,

is it technically possible to use a single joined mesh (made from two non touching meshes in uv space) and assign it to a single surface (closed in one direction) as the mapping mesh ? Something like this:

The reason for this question is, if i try to assign this mapping mesh and use _Unwrap, it only unwraps one of the two mesh islands.

Edit: i do not “Unwrap” i mean using the _UV_Editor command.

thanks,
c.

Are you sure the islands are not on top of each other? Earlier this morning I used _Unwrap on a mesh with three disjoint parts, all the same, and they ended up right on top of each other.

Yes, but you will see texture artifacts along the texture seam that does not line up with polysurface edge - unless Advanced Texture Preview is enabled.
You can achieve that by first unwrapping that surface with the one edge selected as seam. Then open UVEditor and unweld the mesh edge you want to split along. Then use Explode to separate the unwelded halves.

Unwrap always starts from the object render mesh. It discards existing custom mapping mesh or any other mapping applied on that channel.

Hi @Jussi_Aaltonen,

actually, i try to setup this mapping programmatically on my own for the cylinder surface (_Unwrap command is not used).

If i set the RenderMesh of the cylinder surface to be a joined mesh cylinder (made of 2 halfes) should _UVEditor pick up this render mesh and unwrap the 2 mesh halfes side by side if i have given them my own texture coordinates ?

I’ve tried programmatically by setting a custom mapping mesh, which did not work. Here is an example i made using the Rhino UI, i just set the Mesh on the hidden layer as CustomMappingMesh:

CM_Cylinder.3dm (81.0 KB)

So it kinda proves, it works when done manually, but i cannot do the same with code ?

_
c.

Not sure what happens in that case. Manipulating render meshes (and relying nothing else manipulates them) is risky. You should be able to setup the custom mapping directly. Here’s an example: rhino-developer-samples/SampleCsCustomMeshMappingCommand.cs at 7 · mcneel/rhino-developer-samples · GitHub

Hi @Jussi_Aaltonen, thanks for this example. I try to assign my mesh (which is not part of the document) with this way and come back with an example if i cannot make it work.

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c.