World Spline Graph

• The WorldSplineGraph class article to learn how to manage world spline graphs via API
• The SplinePoint class article to learn how to manage spline graph points via API
• The SplineSegment class article to learn how to manage spline graph segments via API
• C++ sample for the WorldSplineGraph class illustrating how to manage spline graphs and generate geometry along the graph segments: source/samples/Api/Nodes/WorldSplineGraph
• Samples illustrating use cases of the WorldSplineGraph node included in the Samples suite:
  • world_spline_graph/roads - roads created on the terrain surface
  • world_spline_graph/ropes - ropes, chains, and cables

New points are added to the spline graph by cloninng existing ones. To add a new point do the following:

1. Select the World Spline Graph.
2. Select the desired point, which you wish to clone (Move manipulator will appear).
3. Press Ctrl + D on the keyboard (a new point will be created).
4. Use the Move manipulator to position you new created point.

To adjust position of a point do the following:

1. Select the World Spline Graph.
2. Select the desired point (Move manipulator will appear).
3. Use the Move manipulator as you would do to move a node.

You can also adjust the position of the selected point via the Spline Points section of the Parameters tab:

Tangents control the curvature of the spline segment. To adjust tangent at a point do the following:

1. Select the World Spline Graph.
2. Select the desired point (Move manipulator will appear).
3. Select the desired tangent (in case the selected point is shared by multiple segments, several tangents will be displayed for it). As you select a tangent the Move manipulator appears next to it.
4. Use the Move manipulator as you would do to move a node (the form of the corresponding segment will change).

Up vector controls orientation of nodes placed along the spline segment. To adjust tangent at a point do the following:

1. Select the World Spline Graph.
2. Select the desired point (Move manipulator will appear).
3. Select the desired UP vector (in case the selected point is shared by multiple segments, several UP vectors will be displayed for it).
4. Switch to Rotate manipulator and use it to adjust the desired angle as you would do to rotate a node (the orientation of nodes placed along the corresponding segment will change).
   Notice

   You'll be able to see the effect only when a node is assigned to the corresponding segment.
5. Use the Move manipulator as you would do to move a node (the form of the corresponding segment will change).

Sometimes it might be necessary to merge certain points (e.g. to close a spline). To merge two or more points into one do the following:

1. Select the World Spline Graph.
2. Select points you want to merge with a region selection tool or one-by-one while holding the Shift key pressed.
3. Right-click on a point you want to merge selected ones into and choose Merge To This Point.
4. All points will be merged into one shared by the segments, to which the merged points belonged.

To delete point(s) of the spline graph do the following:

1. Select the World Spline Graph.
2. Select point(s) you want to delete with a region selection tool or one-by-one while holding the Shift key pressed.
3. Press the Del key.

To add a new segment to the spline graph do the following:

1. Select the World Spline Graph.
2. Select the starting point for the new segment to be added (Move manipulator will appear).
3. Press and hold the Shift key and use the Move manipulator to position the ending point of the new segment.
   Notice

   • To create a straight segment, you should drag the manipulator in the direction of the tangent at the starting point.
   • The new added segment uses all settings (assigned nodes, placement modes and parameters) of the previous one.

You can also clone segment(s) by selecting them and moving with the Shift key pressed, or pressing Ctrl + D and placing the clone with the Move manipulator.

To delete segment(s) of the spline graph do the following:

1. Select the World Spline Graph.
2. Select segment(s) you want to delete with a region selection tool or one-by-one while holding the Shift key pressed.
3. Press the Del key.

To assign a source node to selected segment(s) do the following:

• Select the desired segments(s).
• Click Add Node in the Parameters tab.
• In the window that opens, select the required node and click OK.
  Notice

  Source nodes to be assigned to segments and points are stored in *.node files. The node file should contain a Static Mesh, Skinned Mesh, or Projected Decal as a root node.

For each of the source nodes assigned to the selected segment(s) the following settings are available for adjustment via the Parameters tab:

To assign a source node to selected point(s) do the following:

• Select the desired point(s).
• Click Add Node in the Parameters tab.
• In the window that opens, select the required node and click OK.
  Notice

  For a junction point to behave properly an ObjectMeshSkinned node should be assigned, and the number of its bones should correspond to the number of spline segments connected to this point.

For each of the source nodes assigned to the selected point(s) the following settings are available for adjustment via the Parameters tab:

Junctions#

Due to the nature of the mesh, there will be visual artifacts connected with the float precision, if World Spline Graph is exported to a very big object (around 10,000 m from the origin to either side). We recommend splitting such big objects to smaller ones.

A problem may also arise if World Spline Graph, though being not very big, is located very far from the origin (around 10,000 m and further). In this case we advise exporting it to FBX without storing pivot (the Save root transform option should be disabled), or resetting the World Spline Graph position to origin before exporting it to Mesh.