There are four types of toon lines you can edit in Maya: profile, border, crease, and intersection lines. These lines are defined in terms of mesh properties; therefore all geometry types other than meshes are converted to polygon meshes before being passed to the pfxToon node.
Profile lines are silhouette lines occurring where an object turns to be facing away from the view. If using Paint Effects for profile lines, Maya regenerates these lines when the view changes. If using Offset Mesh for profile lines, updating is inherent, so the refresh is not slowed down the way it is with the Paint Effects method. Depending on the view, profile lines may coincide with crease lines (when the crease edges are also in silhouette). For attributes you can use to modify the appearance of profile lines, see Profile Lines.
Crease lines are formed on polygon edges where the bend angle is greater than the defined Crease Angle Min value. Unlike profile lines, crease lines are not view-dependent. For example, you would use them to draw the edges of a cube, even when the edge is facing you. For attributes you can use to modify the appearance of crease lines, see Crease Lines.
Border lines are on edges that are only part of a single polygon face. For example, the edges of a simple plane are border lines. For attributes you can use to modify the appearance of border lines, see Border Lines.
For two objects to have intersection lines between them they must be assigned to the same toon line node. However, you can layer multiple toon line nodes on objects, and if desired use several different toon line nodes just for intersections and others for profile and crease lines.
You can control the appearance of intersection lines using the attributes in the Intersection Lines section of the pfxToon node. See Intersection Lines. These attributes are similar to those for profile and crease lines and they work in much the same way as they do for the other line types. There is a unique Self Intersect attribute. The Intersection Angle Min/Max attributes control the thick/thin variation of the lines based on how steep the angle is where the surfaces intersect. By making the Min value greater than zero you can avoid creating intersection lines where the two surfaces are relatively flush. You can also generate NURBS curves with history along the intersections using Modify > Convert > Paint Effects to Curves.
