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Branch blending with a unique mesh

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  • Branch blending with a unique mesh

    I'm running into a problem when applying procedural roots to a photogrammetry trunk in ST 8. I am trying to utilize the weld blend, but It seems that something is going wrong with the atlas at export. The ring of geometry that is created at the seam of the roots maps itself to a white square on the atlased (leaf/branch) texture. I assume it is trying to pull from the trunk texture but the exporter is failing to compile that. I thought the problem might be because I have the photogrammetry trunk set to "force out" of the atlas but when I set it to be included, the same problem occurs. I have a seam blend applied to my procedural canopy branches which utilize a wrapping bark texture and it is working fine, so I assume this is a problem when utilizing a non-wrapping, unique mesh and texture.

    Ultimately, I need the photogrammetry trunk to not atlas and I would like the blend geo to map to the non-atlased trunk texture so I don't have to waste texture space on a duplicate of the trunk texture.

    From my understanding ST 7 utilized a second UV channel for weld blends. After talking with our lighting/shader team, there is some concern that vertex alpha won't work with our engine unless the geo that utilize it can be isolated in a material with a different shader applied. Are there plans to make blending on a second uv channel an option or allow for more control over atlasing in the form of multi-materials or assigning atlas groups?


  • #2
    Hello,

    I'm not quite sure I follow what is going wrong with your export. If you could zip up the tree and send it to [email protected], we can take a look. If your assets are scattered, be sure to use "save as with assets" from the file menu into an empty directory, then zip up that directory to send to us. This ensures we get all the assets needed for the tree.


    > I need the photogrammetry trunk to not atlas

    On the material asset is a combobox for the atlassing method. You can change it from "default" to "force out" to keep a particular material out of the atlas.


    > From my understanding ST 7 utilized a second UV channel for weld blends

    Yes, but v8 does not do this. Not all engines/renderers were set up to handle it that way so it was always trouble to get them going, particularly if different materials needed to be blended. v8 instead makes a small piece of geometry with the parent material, and a per-vertex blend amount. If you are using the v8 SDK, then you can definitely handle switching to a different shader in the material callback, and the vertex packer can separate them out into a separate draw call if needed. This is getting a little into the guts of the sdk pipeline, so it's probably better handled at [email protected] as well. Once we figure out what is going wrong with your export, I can walk you through handling the blends better.






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