Houdini 20.0 Nodes VOP nodes

Volume VOP Global Parameters VOP node

Provides outputs that represent all the global variables for the Volume VOP network type.

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This operator provides outputs that represent all the global variables for the volume VOP network type. There are no inputs to this operator.

The Volume VOP operators, such as Gas Field Vex DOP and the Volume VOP SOP, can process multiple volumes simultaneously. Volumes are bound to specific parameters and all bound volumes are available when processing one volume.

Most of the parameters provided refer to the specific volume currently being processed. The exception is Density, which is provided for convenience for simple networks.


Volume VOP Global Variables do not work in cvex shaders.




Outputs include


Position of current voxel.


Value of the density field at this voxel location.

ix, iy, iz

Voxel indices. For Volumes these ranging from 0..resolution-1. For VDBs, they refer to the absolute location. Use volumepostoindex with the orig to get the lowest value of the ix,iy,iz for the current VDB.

resx, resy, resz

Resolution of the current volume.


The center of the current volume.


The bottom left corner of the current volume.


The size of the current volume.

dPdx, dPdy, dPdz

These vectors store the change in P that occurs for each step in the x, y, and z voxel indices.


Position inside the bounding box of the volume. Each coordinate ranges from 0..1.


The global time at which the volume is being evaluated.


The timestep currently being used for simulation or playback.


The current frame being processed, note this can be fractional.

First to Fourth Inputs

These provide a path to the inputs of the Volume VOP SOP. They can be wired to any VOP that takes a file path for geometry to have the node instead use one of the inputs of the SOP.


See also

VOP nodes