The Add Fur tool on the Hair Utils shelf is a good starting point for any groom, as it automatically creates Guide Groom and Hair Generate objects for the selected skin. You can also select an animated version of the skin, and the tool will create a Guide Deform object, which moves the output of Guide Groom (i.e. groomed guides) with the animated skin. The Hair Generate object generates animated hair from these guides.
Alternatively, you can click the Create Guides tool on the Hair Utils shelf to add guides to your character. This tool is useful because most of the time when creating fur, you only work with the guides in order to set up the initial direction and length of the fur. It is also useful to only create guides on certain regions of the character, merge them into one stream, and then perform hair generation for all of them combined.
Localized grooming is the most common workflow, since different areas of the character have distinct features. For example, the hair on the head of a character is usually quite different from the torso. This method will create multiple Guide Groom nodes, which you can later merge using the Merge Groom Objects tool on the Hair Utils shelf.
Groom the guides using the shelf tools on the Guide Process shelf tab.
The Curve Advect tool is very useful for painting the initial directions of the fur using only a few strokes.
Once you're finished grooming the different parts of your character, use the Merge Groom Objects tool on the Hair Utils shelf to combine the individual grooms into a single stream. The influence radius on the tool creates a seamless transition between segments.
You can then generate hair from the guides on your character using the Generate Hair tool on the Hair Utils shelf.
The hair and fur tools often process large VEX arrays. If you observe memory issues, consider setting the
HOUDINI_VEX_MEMORYCACHESIZEenvironment variable to
Use the Isolate Groom Parts tool to hide Hair Generate objects that don’t operate on the same region as selected Guide Groom nodes. This is useful for speeding up cooking and for getting a clear view of the area you're currently working on. If you have multiple groom regions, simply turn off the Selectable flags on the Hair Generate nodes, select the region you want to work on in the viewport, and click Isolate Groom Parts on the Hair Utils shelf.
Most furry animals typically have random brighter hairs in their fur. To make the character’s fur look more realistic, you can mask a percentage of white hairs using the Add White Hairs tool on the Guide Process tab. This tool creates a
whitehairattribute, which is picked up by the hair shader. Any curve with the attribute set to
1is regarded as a white hair and assigned the White Hair color specified on the shader.
Varying segment counts per curve is useful when grooming a character with varying hair length. Often it makes sense for longer hairs to have more segment counts and increasing segments for the whole character slows things down. The guides also blend between segment counts when the areas are merged. For example, if a character’s body fur has 8 segment counts but the hair on top of the head has 50, there will be a transition between the two.
The visualization of the hair on the minotaur shows guides with high segments in red, few segments in green, and single segments in blue.
Sometimes when you simulate fur for a shot, there are stray hairs that you want to remove or groom. This can easily be fixed, as all tools for static grooming can be used on an animated character.
This example shows a guide that was stretched during animation of a chipmunk running.
Generating fur without any guides is useful for creating things like grass, or very short fur. This saves a significant amount of computation time. Simply turn off the Use Guides checkbox on the Hair Generate object, which will ignore guides completely and create hair straight out from the skin normal as if you didn’t have any guides. You can use the universal controls to set direction (with an attribute), segments, and length further down on the Hair Generate object in the Unguided Hairs section.
Brushing and stroke work should be done on the guides, not the generated hair.