Here are some handy Houdini global variables that are commonly used in parameter expressions. This is for people just starting out with Houdini since I don’t think they will get past the second tutorial without seeing a global variable being used. Make sure you check the Houdini docs for a full listing.
I talked about creating custom global variables in Houdini in a prior #QuickTip. Houdini, however, already has some predefined for you. One global variable that is especially useful and actually required to render out image sequences is the
$F variable. You use the
$F in rendered picture filename numbering e.g.
$HIP/my_cool_image.$F.exr or when you are animating noise or passing it to a
cos() function if you want to animate a cob of corn oscillating back and forth. Yet another one is
$HIPNAME which gives you the name of the scene file without the extension. You can do some fancy naming of renders with this one.
I’ve included a pdf file for your enjoyment. Have fun!