View Full Version : Uving Deforming objects
08-18-2010, 06:34 PM
Does anyone have any tips for creating UVs that will not distort with blendshapes? These are not small deformations either, as I'm trying to simulate fussion and fission of a cellular membrane.
08-19-2010, 08:18 AM
Use procedural textures...more specifically the 3d textures that are projected in 3 space.
You have less control but it is resolution independant and can be made to stick in place.
The issue is that you will then get "swimming" where the texture remains in place, while the geometry deforms. This is probably worse then just accepting the texture stretching.
And technically, UVs do not distort with blendshapes....they stay in place, which is why the textures will stretch when you animate it.
The only other suggestion, is to create UVs of the object while it is in the extreme deformation....this will give you the opposite affect though of getting compressed textures when it is in a default pose.
08-19-2010, 03:09 PM
Thanks for the advice.
I agree that procedurals would be best, but unfortunately this is for real-time so I won't be able to use them, at least not with our engine.
As for the UVs moving, I know that our engine can animate the UV coordinates, but I agree with you that it is mainly the stretching of the texture. Wouldn't the UVs get distorted as well though to a lesser degree? I mean when one lays out the UVs the goal is to match the shape of the polygons. If there are extreme distortions in the model, wouldn't the corresponding UV mapping now be thrown off, and also contribute to the strechting of the texture? Just curious.
I had made another thread dealing with blending UV sets with the blendshapes, so that is why I thought I could, as you suggest, texture the extremes with separate tilable sets. Our engine supports this, but I'm not sure how to set it up in Maya. I was once watching a Gnomon Behind the Scenes Character Modeling DVD with Cajun Hylton, and at one point he mentions dynamic normal maps.
In my mind this is close to defining a particular normal map for a particular blendshape, but maybe this is not how it actually works?
08-21-2010, 09:36 AM
Animating UVs is different them distorting the UVs.
Animating them, animates the entire UV shell.....often seen in things like animated water in games.
UVs , do not move....they remain in place on the texture map. When moving vertices, each pixel is locked to a specific vertice (that is what a UV is) so that when you increase the distance between two vertices, the same pixels will stretch.
If the UVs were to move, they would be looking up a different pixel and therefore the effect would be that of a texture moving acrossed the surface.
In the videos you watched, what you see is a blending of layered textures.....where another texture is exchanged based on animation. The UVs are not moved and the effect is achieved with shaders. But even with this workflow, you can expect the texture to stretch and distort under extreme deformation.
08-21-2010, 09:36 AM
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