ScreenSpaceLines3D are a 3D line primitive whose thickness is constant in 2D space post projection. This means that the lines do not become foreshortened as they receed from the camera as other 3D primitives do under a typical perspective projection. Example Usage: <tools:ScreenSpaceLines3D Points="0,0,0 0,1,0 0,1,0 1,1,0 1,1,0 0,0,1" Thickness="5" Color="Red"> "Screen space" is a bit of a misnomer as the line thickness is specified in the 2D coordinate system of the container Viewport3D, not the screen.

public class ScreenSpaceLines3D : ModelVisual3D, 
	ICompositeRendering, IInternalContent

Public Class ScreenSpaceLines3D _
	Inherits ModelVisual3D _
	Implements ICompositeRendering, IInternalContent

public class ScreenSpaceLines3D extends ModelVisual3D implements ICompositeRendering, IInternalContent