Function Texture Type
A texfunc is a procedurally defined perturbation
of the surface normal, defined by a function.
The values of the X, Y, and Z perturbation expressions
are added to the X, Y, and Z components of the original
normal vector.
![[Texfunc Parameters Dialog]](images/texfuncdef.gif)
Function File:
This pop-up list offers all function files known to the
system for selection. If a file is active, then the
variables in that file can be selected for one or several
of the vector coordinates. Otherwise, the coordinates
must be entered as expressions.
Edit...
Start the text editor that was configured in the project
preferences to edit the function file.
New...
Create a new function file, and start the text editor
to edit it.
Perturbation X/Y/Z:
The values that shift the normal vector in
each coordinate direction.
Those can either be selected from the variables in the
function file as selected above, or they may be entered as
expressions.
An expression can contain numeric values, operators
and all functions and variables known to the material.
If an expression is not valid, then the entry field
will have a red background, and the message bar at the
bottom of the dialog will show a diagnostic message.
Real Arguments
Rayfront will check the selected function file to
decide how many real arguments the material definition
should supply. If this number is greater than the
mandatory arguments specifying the basic properties,
then the expected number of entry fields in the list
is made available. Supplying those arguments is
optional, but failing to do so may result in runtime
errors when the selected function relies on a specific
argument which is not set.
The Transformation page
of the dialog can be used
to transform the vector, possibly to bring it in alignment
with the geometry of the surface the texture modifies.
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