All edges in the supplied edge group are enacted as constraints in the output triangulation. Note that edge groups edges do not need to exist as primitive edges in the input. As an example, using the expression “p10-20 p16-24” as the constraint edge group ensures that points 10 and 20 are connected with an edge in the output as are point 16 and 24.

Specifies that the edges of the given polygons should be preserved in the final triangulation.

Constrain to the set of primitives that are incident to an edge that intersects the silhouette of the projected input. The silhouette is formed from the edges whose incident primitives are oriented on opposite sides of the projection.

Allows edges to be inserted into the triangulation for the purpose of creating closed boundaries formed from the constraint edges. This greatly improves the quality of the final mesh when removing triangles that are outside of the constraint boundaries.

Enables use of exact predicates when splitting triangles. This can improve triangle quality, but may be slower.

Simplifies the constraint set by removing all interior points.

Removes triangles that are outside of the constraint group.

Removes triangules outside the boundary of the constrained polygons.

Removes triangles outside the boundary of the silhouette.

Improves the quality of the triangulation by adding new points. The triangulation will include some new points beyond the ones in the input, but the triangles will have better shapes.

If you start with the following points:

With Refine off, Triangulate 2D will create triangles using the available points, and may in the process introduce undesirable long skinny triangles:

With Refine on, Triangulate 2D will add points to create better triangles conforming to the Maximum Area, Minimum Angle, and Minimum Edge Length parameters.

Allows edges to be inserted into the final triangulation in order to improve triangle quality.

An angle threshold between 90 and 180 degrees on the angles of newly formed triangles from the insertion of edges. To avoid violating this criteria, the operator will insert additional edges.

The minimum angle, in degrees, for the interior of each triangle. Increasing this value to get more symmetrical triangles and eliminate long skinny triangles. Values larger than 30 degrees cannot be guaranteed and often force the refinement to go for ever, and only stopped by the reaching the maximum allowed number of points (Maximum New Points).

An optional specification on that target triangle size during relaxation.

To avoid over-refinement in a local area, you can specify a minimum length for the longest edge of a triangle that is allowed to be further refined. Once all edges of a triangle become shorter than the specified length, no further attempts are made to improve the shape of the triangle.

Limits the number of new points that can be added during triangulation. New points might be added to satisfy constraints or during refinement, up to this limit. This is useful to ensure that the triangulation doesn’t run forever, and should usually be set to a value much larger than the number of points you expect to generate.

The number of iterations used to regularize the triangulation. More iterations will result in more uniform triangles, but will take longer.

When regularizing the triangulation, this allows the interior points or the original projection to be moved in the plane.

When on, triangles of the generated triangulation are transformed to use the original 3D positions of the input points. Newly generated points (for refinement or constraint conflict resolution) are accordingly assigned interpolated positions based on the 3D positions of the input points.

Keep all input primitives (except the constraint primitives) in the output in addition to new primitives created during triangulation. When off, the input primitives do not appear in the output.

Recomputes point normals (if they exist).

When on, points outside the input point group are deleted from the output.

For any given 2D position only one point can be inserted into the triangulation. If multiple points have the same 2D position only one of them is inserted into the triangulation and the others are ignored. When on, these duplicate points are deleted from the output. Otherwise, they are left in as isolated points.

Outputs a group of points used to split crossing constraints.

Outputs an edge group containing the edges specified from the constraints.

The triangulation and refinement algorithm implemented by this node is “randomized” in nature, meaning that its peek performance is expected with high probability only if the input points are processed in “random” order. Since Houdini node outputs must be deterministic, a fixed random-like reordering of the input points, determined by this parameter, is used. In the majority of cases, this fixed reordering should perform close to optimal but it is theoretically possible for any fixed reordering to perform poorly for a specific point set. Changing the seed value in such case may have tangible effects on the speed of the triangulation although it might affect the generated output, particularly in terms of the point and primitive numbers.