Guide Curves are normal Maya curves used to guide fibers or instances in Yeti. Its main utility is to be able to connect them to a Rig and animate the fibers or instances easily and efficiently.
To use them in a Yeti graph, you first need to create Guide Sets, which are groups of Guides that will be brought to the graph through the Import node. To create them, select all the guides you want to put in the group and go to Create-> Set-> Set. Then go to the Graph-> Input Guide Set tab of the top node of Yeti and add all the sets you've created. To add or remove curves to a Guide Set, you can use the Relationship Editor in Windows-> Relationship Editors-> Sets.
Important: The pivot of each curve must always be in the [0,0,0], being only possible to move its points in Edit Mode (F8). If the pivot is out, there will be an accumulation of this translation and incorrect positioning of the fibers and instances (Double Transformation). To place a pivot in [0,0,0], we can use the Freeze Transformations command followed by Reset Transformations, in the Modify tab. It is also important that the first control point of each curve is close to the mesh, not infiltrating it nor too far from its surface. We can use the Snap function to position the first point of the curve close to the mesh. If this distance is not adequate, instances or fibers may lose their reference and behave incorrectly. Finally, if the feathers are being instantiated inverted, you must invert the direction of the curve in Curves-> Reverse Direction or even rebuild them in Curves-> Rebuild.
Guides Sets are imported into the graph and can be used on the Scatter node to control density, on the Grow node to control the fiber size and with the Guide node that will work as a Comb and Clumping together.
When we add a Guide Set on the top node of the Yeti, extra attributes are released on each curve to control the wire parameters. These parameters are like the attributes of a Groom, but already automatically connected to their functions.
We define your area of influence with the Inner and Outer Radius. The Inner Radius will be the area where the curve parameters will act with 100% effect. The Outer Radius stipulates how far the effect of these parameters will be decayed, and outside it will have 0% effect.
Example File: GuideSet_Attributes..ma
Guide Sets deforming Grooms
The parameters that the Guide Set creates on curves are pretty limited compared to everything that the Groom has to offer. However, it is not possible to place Rig controllers in a Groom, which makes it impossible to directly animate your guides.
One way to take advantage of each method is to create a system in which the Guide Set controls the deformation of Groom guides, but all attributes are created and controlled by Groom. So we can animate a Groom.
We put a Groom guide in the same position as each curve, hitting its size to match the curve. You can also select all the curves (never the group) and use the command below in the Script Editor to automatically convert it to a Groom.
PgYetiConvertGuideSetToGroom (string guide_set, string mesh_object, float stepSize)
The first parameter string guide_set will be the name of the Guide Set created.
The second string mesh_object parameter is the name of the mesh
The third parameter is the resolution of the conversion, with 0.1 being the common value to be used. Always use “ ” for string fields.
Example: pgYetiConvertGuideSetToGroom ("my_guideSet", "bunnyShape", 0.1)
Example File: Guides_Deforming_Grooms.ma