Triangulated mesh's cut-off zones

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Diana Kennedy
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Triangulated mesh's cut-off zones

Post by Diana Kennedy » Wed Jul 31, 2019 2:00 pm

As we know, triangulated mesh "cuts of" some parts of the bitmap its applied to.
This may be a useful feature for those who need it. It isn't for me, since I only import PNG files which have been previously worked to have a clean, transparent background.
Therefore this feature is a bit annoying for me. The mesh often cuts of parts of my image, when I want to add points and therefore make the mesh more complex.
Despite f trying, I could not figure out yet the rules regarding what will be cut of and why.

So my question is : Is there a way to simply turn off the cutting feature ? Maybe there's a script I could add ?

Would be great to have some help here. I love the mesh, but this behavior is a needless obstacle.
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Diana Kennedy
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Re: Triangulated mesh's cut-off zones

Post by Diana Kennedy » Sat Sep 14, 2019 5:45 pm

Any idea for this issue?
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synthsin75
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Re: Triangulated mesh's cut-off zones

Post by synthsin75 » Sat Sep 14, 2019 7:25 pm

If your images already have transparent backgrounds, there's no reason your mesh can't be big enough to ensure it doesn't cut off any of the image.
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Greenlaw
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Re: Triangulated mesh's cut-off zones

Post by Greenlaw » Sat Sep 14, 2019 7:49 pm

What Wes suggests is correct...just make the mesh bigger than your image with the transparent background.

Another advantage with making the mesh bigger is that it preserves any curved edges in your bitmap image; triangulated mesh edges are always faceted, not curved, and you usually don't want that.

Bonus Tip: Don't use the Crop Tool with bitmap layers if you want use a custom mesh warp. The Crop Tool is not compatible with mesh warping.
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Diana Kennedy
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Re: Triangulated mesh's cut-off zones

Post by Diana Kennedy » Sat Sep 14, 2019 8:34 pm

Thanks, but this doesn't really adress my issue. Maybe I didn't express myself clear enough. I DO make the mesh big enough. Problem is that when I add some extra points to the mesh, in order to have a better control over the part in the bitmap I want to animate, THEN parts of the bitmap are cutted out. Therefore I have always to work with the basic mesh, since don't know the reason for this cutting behavior nor a way to avoid it.
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synthsin75
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Re: Triangulated mesh's cut-off zones

Post by synthsin75 » Sat Sep 14, 2019 9:02 pm

I'd have to see the mesh myself to know for sure, but triangulation tries to maintain any strokes. So it may be that closed strokes are being interpreted as holes.
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Re: Triangulated mesh's cut-off zones

Post by Greenlaw » Sat Sep 14, 2019 9:06 pm

Can you post an example? That would make it easier to understand the problem.

This is purely another guess but based on what you wrote, perhaps you need to re-triangulate the mesh to adopt the changes you made? I usually keep a backup layer with the untriangulated mesh just for this purpose, and I make my changes to a duplicate of this backup before triangulating the duplicate.
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