You can use curves to create controlled strokes as you sculpt or paint, with the curves acting as guides for your sculpt and paint strokes. You can create curves by drawing freehand with the Create Curve tool, or using a set of pre-defined curve shapes.
Curves are useful for creating features like ridges on armor, hair-like strokes for hair, or for adding details on hard, inorganic-shaped models. Using Stroke on Curve, you can also use curves to achieve an even, stamp effect along a path. (See Sculpt or paint using curves.)
There are two types of curve in Mudbox. 3D curves are drawn directly on the surface of a model, and stay with the model as you zoom, tumble, and otherwise change your perspective on the scene. 2D curves are drawn on the view plane (as if drawn on glass in front of your model), and they stay in place as you adjust your view.
Both types of curve can be used to guide your sculpt and paint strokes. To use a 2D curve, simply adjust the position of objects and your view of the scene until the object displays under the 2D curve. For more information on repositioning curves relative to the camera plane, see Move, rotate, or scale 2D curves.
