rdurnin

Hello and I am looking at implementing the VAT shaders for WGSL and am having some issues with converting the softbody data and shaders. For WebGPU purposes I would like to export low-dynamic-range textures and to use the bounds to normalize the data in the vertex shader, much the same as what I see in the Unity implementation.

The issue I am having is with the data from the rotating softbody cube which exports data clamped for part of the simulation to 1 and also seems to change in scale over time (this could be a visual result of the clamping). To simplify the export process I have replaced the cube with a Grid (2x2 columns and 4x4 size). Please see the attached spread sheet for the export results (and a chart showing time sliced data).

After looking through the HDA code it would seem like the problem is related to when the bbox is calculated (for scaling the pixel data for pos) as it updates every frame and we use the single value for the entire sequence in the shader. The problem also appears to be related to when the corners of the grid (or cube) rotate outside the static object's bounds.

Please let me know if you have any advice for exporting softbody simulations as png textures or if there are changes I can make to the HDA which will improve performance. A prior version of the plugin included a cloth simulation of a tearing flag and that data continues to function, although the object does not rotate or transform.

Attached files:

Error Scene
Unpacked Data (norm)
Denormalized Data (chart)

Hello,

I have constructed a SOP network which uses a scatter network to instantiate props around the scene (10k+) and have some questions about the GLB file output.

• The file is massive, and remains so even after using gltf pack to convert the instances to GPU instances. Why would the container for an object instance be so big? Despite disabling extra attributes?
  
• Using the instance node (OBJ) or copy to points (SOP) produces files of the same size. The draw calls look correct in my GLTF viewer, but this is likely because the objects share the same material and not because they are instanced.
  
• What should be the expected result of 'pack and instance' (Copy To Points SOP)? Enabling this switch causes the GLTF export to crash.
  

If there is a preferred method to creating lightweight instances in a Houdini authored GLTF, please let me know. Using a similar approach (Maya->MASH->Instances), creates a file which compresses down significantly and I would like to avoid recreating my graph in another sw.

Thanks,
r

Hello,

I am working with the LabsMapbox node and am trying to rebuild the node tree in another file. In walking the node graph I have found a node which shows an expression ch('../total_size') which I can't deduce the value for. I assume it is being calculated from some combination of the input node's values, but I can't figure out how to debug it. I have tried viewing channels, but it only shows the expression as written in the editor.

Is there a way, using python or otherwise, which I can ask for the value? This would allow me to determine which inputs are being used to generate it, and more easily emulate the graph.

Thanks for any help you might lend,
r