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Region Graph Editing

Some RoadRunner data models are built on top of graphs of curve-bounded regions. This topic provides common steps to create, delete, and modify these region graphs.

Many of the editing concepts for region graphs are similar to the concepts for Design Scenes. For example, you can create, edit, and delete curve-based graph edges that behave like most curves in RoadRunner.

Region graphs differ in two regards:

  • Edge Connectivity — Graph edge curves can be connected end-to-end.

  • Regions — Whenever a closed loop of graph edges is formed, a region is created in the interior.

Refer to the Design Scenes page for general information about selecting and deleting objects.

Create a Graph Edge Curve

  1. Select the graph region tool that corresponds to the type you want to create (for example, select the Surface Tool if you want to edit surfaces).

  2. If you want to start the new edge at an existing node, select the existing node. Otherwise:

    1. Ensure that no objects are selected (for example, by using the Edit > > Deselect All option in the menu bar).

    2. Right-click (and optionally drag) to create an initial graph node.

  3. Optional: Move the pointer over an existing node if you want to end the curve at that node.

  4. Right-click (and optionally drag) to create a second graph node and a graph edge curve in between.

Split a Graph Edge Curve

  1. Select the graph region tool that corresponds to the type you want to create (for example, select the Surface Tool to edit surfaces).

  2. Right-click a graph edge curve to split it into two curves.

Move a Graph Node

  1. Select the graph region tool that corresponds to the type you want to create (for example, select the Surface Tool to edit surfaces).

  2. Click and drag the graph node you want to move.

Change the Tangents of a Graph Edge Curve

See Tangent Editing.

Create a Region

Regions are automatically created whenever a closed loop of graph edges is formed:

Sequence of connected graph edge curves (no region)

Region is automatically created when the open ends are connected.

Split a Region

Each closed loop of graph edges automatically forms a region, so one region can be split into two by forming a path of graph edge curves between two of the points on the region exterior:

Single region

Region is automatically split into two regions when two closed loops are formed.

Regions With Holes

Only the Surface Tool fully supports holes.