Houdini 17.0 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.

Note

Volume VOP Global Variables do not work in cvex shaders.

Inputs

None.

Outputs

Outputs include

P

Position of current voxel.

density

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.

center

The center of the current volume.

orig

The bottom left corner of the current volume.

size

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.

BB

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

Time

The global time at which the volume is being evaluated.

Timeinc

The timestep currently being used for simulation or playback.

Frame

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.

Parameters

Examples

The following examples include this node.

attribfromvolume Example for Attribute from Volume geometry node

This example demonstrates how the AttribFromVolume SOP can be used to transfer volume values onto point attributes.

volumecompress Example for Volume Compress geometry node

This example shows how to use the Volume Compress SOP to reduce the memory requirements of volumes without too adversely affecting their appearance.

DetectOverlap Example for Volume Merge geometry node

This example shows how to detect the overlapping regions of many incoming volumes procedurally using Volume SOP and Volume Merge SOP.

barycenter Example for Volume Reduce geometry node

This example shows how to use the Volume Reduce SOP to compute the barycenter of a 3d object.

volumeresample Example for Volume Resample geometry node

This example shows how to use the Volume Resample SOP to increase and decrease the resolution of a volume. It also shows how the different sampling options affect the quality of the resulting volume.

volumesurface_explicitgrade Example for Volume Surface geometry node

This example shows how to use the Volume Surface SOP to surface an SDF using another volume to specify the triangle sizes.

volumesurface_hierarchy Example for Volume Surface geometry node

This example shows how to use the Volume Surface SOP to surface a hierarchy of SDFs using explicit grading.

ImportVolumes Example for Volume VOP geometry node

This example shows how to import multiple volumes into a Volume VOP SOP.

PointCloudLookup Example for Point Cloud Iterate VOP node

This example shows how to accomplish point cloud lookups for volumes using pcfilter and pciterate. It demonstrates how to iterate over and import values returned by a query.

See also

VOP nodes