A linear is a special type of game object; it defines a geometric shape that has a set of control points.
The Palette provides an object for creating lines and curves:
Polylines and spline curves have endpoints that anchor the object’s two ends in the world. Dragging a polyline’s or curve’s endpoint repositions it. When laying out a linear onto another surface, you can snap the control points to other surfaces the same way you snap to any other object.
For a demonstration of how to create linears, view the “Creating Linears” video, either on the GitHub site or on SHIP.
The figure below shows three linears in the Design View, each with five control points in addition to their endpoints. Each linear is defined with the same parameters; the blue one is a polyline, the green one is a CatmullRom spline, and the orange one is a Bezier curve. The figure shows the linears from four different projection views: perspective, top, front, and left. These linears could represent a short, but complex, flight path of a game object.
You can create closed polylines and curves by selecting the linear, opening the Property Editor, and setting the Is Closed property to True. Closing a linear connects the linear’s two end control points to form a closed shape. the figure below shows the same three linears as in the figure above, but the linears are now closed.