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Wake me up when the deformable assets in VFX and video games etc are represented by SDF's instead of meshes. How do you rig an SDF for animation (eg. skeletal,

Wake me up when the deformable assets in VFX and video games etc are represented by SDF's instead of meshes. How do you rig an SDF for animation (eg. skeletal, for a humanoid figure)?

naasking 2y ago
The signed distance function defining a solid can be parameterized by anything. Common ones are results of a finite element analysis, thereby allowing you to make the structure thinner where it doesn't need strength. In the case animation, parameterize it by a global clock, and each frame the objects are in slightly different positions dictated by a rough physics model (like a person's skeleton).
- nineteen999 2y ago
  Bad topology generated by marching cubes from an SDF is not going to replace hand tuned topology for animated meshes in VFX and video games in the near future. Even highly dense Nanite meshes in UE5 don't support skeletal deformation yet.
johnnyanmac 2y ago
To be fair, I don't exactly think the mesh system was made with deformation in mind either. We kind of just hammered on rigs/skinning on top of it, then learned all the ways not to model for that workflow. Shame that NURBS never really took off in the gaming scene. I get it from a hardware standpoint (GPUs like triangles, and we can cut quads into triangles), but NURBs solve so many problems that trianglular meshes just hack their way around. >How do you rig an SDF for animation I imagine with the most unholy mathematical models imaginable. Dreams did it, so it's not impossible. But the results seen definitely don't measure up to a AAA standard (at least in Dreams).
- nineteen999 2y ago
  Right, but the skeletal mesh workflow has been in production use and being developed since the late 1990's. It's extremely mature and a mind boggling amount of $$$ have been spent on optimizing it and designing hardware around it since that time. I appreciate all the tangential discussions, but the two key points im trying to make are: 1) SDF's are not likely to supplant detailed hand modelled/cleaned up meshes any time soon, but will continue to be used alongside and in conjunction for all kinds of other cool stuff (soft shadows, ambient occlusion, fonts etc as seen in UE4/UE5) 2) ergo, a modeller based around SDF's is not going to replace mesh based modellers like Blender, Maya etc anytime soon, even to a small degree.
  - johnnyanmac 2y ago
    So, sunk cost fallacy? I suppose. I don't think anyone fundamentally disagrees with you, but an author making a toy 3d modeler in a week usually doesn't have the goal to disrupt an entire industry. It's a nice place to consider on a fundamental level what tools like these could and couldn't do that current work flows cannot.

Wake me up when the deformable assets in VFX and video games etc are represented by SDF's instead of meshes. How do you rig an SDF for animation (eg. skeletal, for a humanoid figure)?

naasking 2y ago

The signed distance function defining a solid can be parameterized by anything. Common ones are results of a finite element analysis, thereby allowing you to make the structure thinner where it doesn't need strength. In the case animation, parameterize it by a global clock, and each frame the objects are in slightly different positions dictated by a rough physics model (like a person's skeleton).

nineteen999 2y ago
Bad topology generated by marching cubes from an SDF is not going to replace hand tuned topology for animated meshes in VFX and video games in the near future. Even highly dense Nanite meshes in UE5 don't support skeletal deformation yet.

johnnyanmac 2y ago

To be fair, I don't exactly think the mesh system was made with deformation in mind either. We kind of just hammered on rigs/skinning on top of it, then learned all the ways not to model for that workflow. Shame that NURBS never really took off in the gaming scene. I get it from a hardware standpoint (GPUs like triangles, and we can cut quads into triangles), but NURBs solve so many problems that trianglular meshes just hack their way around. >How do you rig an SDF for animation I imagine with the most unholy mathematical models imaginable. Dreams did it, so it's not impossible. But the results seen definitely don't measure up to a AAA standard (at least in Dreams).

nineteen999 2y ago
Right, but the skeletal mesh workflow has been in production use and being developed since the late 1990's. It's extremely mature and a mind boggling amount of $$$ have been spent on optimizing it and designing hardware around it since that time. I appreciate all the tangential discussions, but the two key points im trying to make are: 1) SDF's are not likely to supplant detailed hand modelled/cleaned up meshes any time soon, but will continue to be used alongside and in conjunction for all kinds of other cool stuff (soft shadows, ambient occlusion, fonts etc as seen in UE4/UE5) 2) ergo, a modeller based around SDF's is not going to replace mesh based modellers like Blender, Maya etc anytime soon, even to a small degree.
- johnnyanmac 2y ago
  So, sunk cost fallacy? I suppose. I don't think anyone fundamentally disagrees with you, but an author making a toy 3d modeler in a week usually doesn't have the goal to disrupt an entire industry. It's a nice place to consider on a fundamental level what tools like these could and couldn't do that current work flows cannot.