Houdini 16.5 Nodes VOP nodes

Output Variables and Parameters VOP node

Provides inputs representing the writable output variables of the shader network.

Every VOP network type has a set of global variables associated with it. These are the variables inherent to the VEX context that the VOP network operates in. For shading contexts (such as Surface and Displacement) these will be variables like the position of the point on the geometry being shaded (P), or the normal of the surface at the point being shaded (N). For SOP or POP Operator networks, these variables include the position of the point being manipulated (P), and the point number of the point being manipulated (ptnum).

The inputs on this node are a subset of the outputs available on the Global Variables node, where the globals node represents all available global variables and this node represents new values for the variables you can change.

Every VOP network starts with this node already in the network. It is possible to delete it (for example, if you only deal with export variables and don’t care about global outputs) but you should probably avoid doing so.


This node drives the generation of VEX code from the VOP network. Only nodes you directly or indirectly connect to the output node will be used to generate shader code.


Generate Code for This Node Last

You should always have this option turned on unless you have some backwards compatibility problem with old shader code.

When this option is on, the code for this node appears after the code for all other nodes in this VOP Network, ensuring global variable values are not modified until the very end of the function.

Parameter order table

Lets you change the order and grouping of shader parameters in the generated user interface.

  • Drag rows or use the up-arrow button to reorder parameters.

  • Click the right-pointing triangle at the end of a parameter row to put the parameter inside a new group. Groups appear as tabs in the user interface.

  • Click a group start row (a row containing a { character) to rename the group.

See also

VOP nodes