I got into Vertex Animation Textures recently for the purposes of optimization for game development. I have achieved a successful result in exporting a single animated asset and it functions properly in Unreal Engine 5.4. I got there by using the "Labs Vertex Animation Textures" ROP (specifically the "Soft Body Deformation" setting), and I managed to find the needed resources to understand it fairly easy.
I can't however find any useful information about exporting LODs using the "Labs Vertex Animation Textures" ROP. I have read that it requires a "lod#" point group, which I managed to create successfully, and a "lod0_ptnum" point attribute, which is the issue that I ran into. As far as I interpreted the source documentation, that should be an attribute that lets each point in the LODs after 0 read the information stored in the texture maps that were baked for LOD0 by copying the data from a certain point from LOD0.
What I did was to find the closest point from LOD0 to each point in the subsequent LODs and store its point number in the "lod0_ptnum" attribute by using the "nearpoint" VEX function. The results were consistent, but this produced a different sub-set of points from LOD0 in each subsequent LOD, and I'm not sure if that should be the case. The "Vertex Animation Textures" ROP doesn't give me any warnings, but the results in UE are terrible (LOD0 functions perfectly fine, but the subsequent LODs have massive artifacts), which lets me think that the points of the LODs after 0 are not reading the correct information from the texture.
I have two questions that I couldn't find an answer to:
How should I approach the creation of this "lod0_ptnum" attribute?
Is there something different in the Unreal Engine setup compared to the one for an FBX that doesn't contain LODs that could be causing the issue?
Thank you in advance! Cheers!
Here is how the LODs look like in UE:
LOD0 -
LOD1 -
LOD2 -
Here is the source documentation for the "Vertex Animated Textures" ROP that I'm using for reference:
https://www.sidefx.com/docs/houdini/nodes/out/labs--vertex_animation_textures-3.0.html [www.sidefx.com]