Houdini 16.5 Nodes VOP nodes

Volume Sample VOP node

Samples the value of a volume primitive.

Samples a specific volume primitive. Returns 0 if primnum or input_index is out of range, or the given primitive is not a volume primitive.

Note

This node is only available in the geometry context.

Using volumesample() functions on points outside of a volume box will extend the sign distance field if the volume boundary is SDF. The distance to the bounding box is added to the streaked bounding box value.

The following diagram shows how the SDF extension works.

Boundary values

  • Constant values mean there is a value that all outside samples are set to (usually 0). So even if the border voxel is 1, as soon as you peak outside it is 0.

  • Streak means the boundary value is held into the surrounding area. So an out-of-bound sample is clamped to the volume and the value samples. This means a value of 1 at the boundary will streak into the surrounding space.

  • Repeat means space is tiled with the volume.

See also

VOP nodes