TYPE: VOP
TITLE: Output Variables VOP

This operator provides inputs that represent all the global variables for the
current VOP network type that can be modified.  There are no parameters and no
outputs to this operator.  Every VOP network contains exactly one of this
operator type.  The Output Variables operator cannot be deleted except by
deleting the parent VOP network.  It is also not possible to create a second
Output Variables operator within a VOP network (even within a subnet).

This operator drives the VEX code generation process for a VOP network.  When
generating code, only operators that are directly or indirectly connected to
an input of the Output Variables operator will actually generate any code.
This operator is also always the last operator to output its code.  It simply
goes through all of its inputs, and sets the global variable corresponding to
each connected input to the value that is wired into it.

The variables available from this operator will be a subset of the variables
available as outputs from the Global Variables operator.  The difference
between these two operators is that the Output Variables operator only provides
inputs for those global variables that can be changed.

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).  Detailed descriptions of
all available global variables can be found in the VEX documentation.

The list of available inputs depends on the current VOP network type.

See also: Global Variables(global), Parameter, Subnet Output(suboutput)
