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UE3 Home > Level Editing > Using SplineLoftActors
UE3 Home > Level Designer > Using SplineLoftActors

Using SplineLoftActors


SplineLoftActors are used to deform staticmeshes along a segment of spline, generated between two or more SplineLoftActors.

Functionality and use

SplineLoftActors deform staticmeshes along splines generated between two or more SplineLoftActors. Each segment of spline can deform a separate mesh. Meshes used in this way will follow the spline along their Z axis. In effect, this means that for deforming things like vines, roadways, etc, the mesh should be arranged so that its long axis is oriented in world-Z. The SplineLoftActor has options for determining what axis to orient to world-up on a per-segment basis (used to align the road mesh so the surface faces the correct orientation, as opposed to following the spline on its side). Current limitations of the spline system include:

  • No collision. The spline system does not currently deform the mesh's collision along the spline.

  • No interpolation between spline segments of world-up.

  • No tiling of meshes. Each segment of spline will stretch a single mesh from beginning to end.

  • All meshes begin and end at the SplineLoftActors that make up that segment. It is not possible to control the position of the mesh along the spline.

Adding a SplineLofted mesh to the world

Adding a spline to the world is very easy. Find SplineLoftActor in the Actor Browser beneath SplineActor. Add one to the world, and open its properties. Find the mesh you want to apply to the spline, select it, and apply it to the Deform Mesh property in the SplineLoftActor. Duplicate the existing SplineLoftActor, and it should immediately begin rendering the spline-deformed mesh. By moving the tangents for the two SplineLoftActors, you can modify the curvature of the spline.

Splitting and Bisecting Splines

Splines are always created between two or more SplineLoftActors. To create a spline that branches, take an existing two point spline, duplicate one of the points, then select the original point and the point that has now been orphaned. Hitting the . key (period) will connect two spline points if they don't share an existing connection, or reverse the direction of the spline if a connection exists. This can be repeated to create multiple branch points.

Properties of the SplineLoftActor

There are a few properties within the SplineLoftActor that can be modified to customize the appearance of the deformed mesh.

Deform Mesh Materials

Deform Mesh Materials is a dynamic array that can be populated with materials to override the default ones used by the base mesh. Any material overrides done on the spline must be done here, as dragging a material onto the spline mesh from the Content Browser will be overridden if any changes are made to the spline.


The Offset values allow for moving of the mesh off of the spline. This offset is local to the spline actor.


Roll will twist the mesh along the spline's axis. This value is interpolated from spline segment to spline segment.

Scale (X and Y)

Each segment of the spline can scale the spline in both the X and Y axes (Z is the direction of the spline and explicitly set by the distance between connected SplineLoftActors).

Smooth Interp Roll And Scale

As the name implies, this flag allows for smooth interpolation of values in Roll and Scale between segments. If this flag is turned off, the interpolation will be linear instead.

World XDir

This vector defines the 'up' vector for the spline, which influences the base rotation of the mesh on the spline. It is recommended that this value be set to a vector that the spline does NOT travel along, as it will cause significant twisting artifacts.