Curve Output

Curves authored in Houdini are emitted on the Godot side as Path3D nodes parented under HEGoNode3D/Outputs. Each curve part becomes one Path3D with a Curve3D resource populated from the Houdini control points.

Curve Creation

Every curve primitive in the cooked HDA produces one Path3D node. The control points (P) are added in order to the Path3D’s Curve3D.

Higher-order NURBS and Bezier curves are tessellated into linear segments on the Houdini side during cook — HEGo sets refineCurveToLinear = true and curveRefineLOD = 8.0 on the session’s HAPI_CookOptions. The positions that arrive in Godot are therefore dense polylines sampled from the source curve, and type / order in the fetched data reflect the original primitive, not the refined geometry.

Primitive Attributes

Curve output placement is controlled by primitive attributes:

Attribute Name	Attribute Type	Attribute Owner	Description
hego_node_path	String	Prim	Output node path/name under HEGoNode3D/Outputs. Intermediate names become Node3D containers; the last path component is the name of the Path3D itself. When missing, a default name of the form Curves/Curve3D_<type>_<index> is used.

Splitting Output into Multiple Curves

One HDA can emit many curves — assign different hego_node_path values across primitives to place them under separate Node3D containers, mirroring the pattern used for mesh output. Reusing the same path on a recook updates the existing Path3D in place rather than creating duplicates.

Fetching Curves Directly

For custom workflows, HEGoAssetNode.fetch_curves() returns the raw curve data (positions, order, knots, requested prim/point attributes) as an Array of dictionaries, so advanced users can build their own curve resources or custom scene structures.