Geometry Nodes: Curve and mesh topology access nodes

This patch contains an initial set of nodes to access basic
mesh topology information, as explored in T100020.

The nodes allow six direct topology mappings for meshes:
- **Corner -> Face** The face a corner is in, the index in the face
- **Vertex -> Edge** Choose an edge attached to the vertex
- **Vertex -> Corner** Choose a corner attached to the vertex
- **Corner -> Edge** The next and previous edge at each face corner
- **Corner -> Vertex** The vertex associated with a corner
- **Corner -> Corner** Offset a corner index within a face

And two new topology mappings for curves:
- **Curve -> Points** Choose a point within a curve
- **Point -> Curve** The curve a point is in, the index in the curve

The idea is that some of the 16 possible mesh mappings are more
important, and that this is a useful set of nodes to start exploring
this area. For mappings with an arbitrary number of connections, we
must sort them and use an index to choose a single element, because
geometry nodes does not support list fields. Note that the sort
index has repeating behavior as it goes over the "Total" number of
connections, and negative sort indices choose from the end.

Currently which of the "start" elements is used is determined by the
field context, so the "Field at Index" and "Interpolate Domain" nodes
will be quite important. Also, currently the "Sort Index" inputs are
clamped to the number of connections.

One important feature that isn't implemented here is using the winding
order for the output elements. This can be a separate mode for some
of these nodes. It will be optional because of the performance impact.

There are several todos for separate commits after this:
- Rename "Control Point Neighbors" to be consistent with this naming
- Version away the "Vertex Neighbors" node which is fully redundant now
- Implement a special case for when no weights are used for performance
- De-duplicating some of the sorting logic between the nodes
- Improve performance and memory use of topology mappings
- Look into caching some of the mappings on meshes

Differential Revision: https://developer.blender.org/D16029

1 files changed, 9 insertions, 0 deletions

diff --git a/source/blender/nodes/NOD_static_types.h b/source/blender/nodes/NOD_static_types.h
index 574a8dcab96..457f3468e5e 100644
--- a/source/blender/nodes/NOD_static_types.h
+++ b/source/blender/nodes/NOD_static_types.h
@@ -303,6 +303,8 @@ DefNode(GeometryNode, GEO_NODE_CURVE_SPLINE_PARAMETER,0, "SPLINE_PARAMETER", Spl
 DefNode(GeometryNode, GEO_NODE_CURVE_SPLINE_TYPE, def_geo_curve_spline_type,"CURVE_SPLINE_TYPE", CurveSplineType, "Set Spline Type", "Change the type of curves")
 DefNode(GeometryNode, GEO_NODE_CURVE_TO_MESH, 0, "CURVE_TO_MESH", CurveToMesh, "Curve to Mesh", "Convert curves into a mesh, optionally with a custom profile shape defined by curves")
 DefNode(GeometryNode, GEO_NODE_CURVE_TO_POINTS, def_geo_curve_to_points, "CURVE_TO_POINTS", CurveToPoints, "Curve to Points", "Generate a point cloud by sampling positions along curves")
+DefNode(GeometryNode, GEO_NODE_CURVE_TOPOLOGY_CURVE_OF_POINT, 0, "CURVE_OF_POINT", CurveOfPoint, "Curve of Point", "Retrieve the curve a control point is part of")
+DefNode(GeometryNode, GEO_NODE_CURVE_TOPOLOGY_POINTS_OF_CURVE, 0, "POINTS_OF_CURVE", PointsOfCurve, "Points of Curve", "Retrieve a point index within a curve")
 DefNode(GeometryNode, GEO_NODE_DEFORM_CURVES_ON_SURFACE, 0, "DEFORM_CURVES_ON_SURFACE", DeformCurvesOnSurface, "Deform Curves on Surface", "Translate and rotate curves based on changes between the object's original and evaluated surface mesh")
 DefNode(GeometryNode, GEO_NODE_DELETE_GEOMETRY, def_geo_delete_geometry, "DELETE_GEOMETRY", DeleteGeometry, "Delete Geometry", "Remove selected elements of a geometry")
 DefNode(GeometryNode, GEO_NODE_DISTRIBUTE_POINTS_IN_VOLUME, def_geo_distribute_points_in_volume, "DISTRIBUTE_POINTS_IN_VOLUME", DistributePointsInVolume, "Distribute Points In Volume", "Generate points inside a volume")
@@ -366,6 +368,13 @@ DefNode(GeometryNode, GEO_NODE_MESH_PRIMITIVE_UV_SPHERE, 0, "MESH_PRIMITIVE_UV_S
 DefNode(GeometryNode, GEO_NODE_MESH_TO_CURVE, 0, "MESH_TO_CURVE", MeshToCurve, "Mesh to Curve", "Generate a curve from a mesh")
 DefNode(GeometryNode, GEO_NODE_MESH_TO_POINTS, def_geo_mesh_to_points, "MESH_TO_POINTS", MeshToPoints, "Mesh to Points", "Generate a point cloud from a mesh's vertices")
 DefNode(GeometryNode, GEO_NODE_MESH_TO_VOLUME, def_geo_mesh_to_volume, "MESH_TO_VOLUME", MeshToVolume, "Mesh to Volume", "Create a fog volume with the shape of the input mesh's surface")
+DefNode(GeometryNode, GEO_NODE_MESH_TOPOLOGY_CORNERS_OF_FACE, 0, "CORNERS_OF_FACE", CornersOfFace, "Corners of Face", "Retrieve corners that make up a face")
+DefNode(GeometryNode, GEO_NODE_MESH_TOPOLOGY_CORNERS_OF_VERTEX, 0, "CORNERS_OF_VERTEX", CornersOfVertex, "Corners of Vertex", "Retrieve face corners connected to vertices")
+DefNode(GeometryNode, GEO_NODE_MESH_TOPOLOGY_EDGES_OF_CORNER, 0, "EDGES_OF_CORNER", EdgesOfCorner, "Edges of Corner", "Retrieve the edges on boths sides of a face corner")
+DefNode(GeometryNode, GEO_NODE_MESH_TOPOLOGY_EDGES_OF_VERTEX, 0, "EDGES_OF_VERTEX", EdgesOfVertex, "Edges of Vertex", "Retrieve the edges connected to each vertex")
+DefNode(GeometryNode, GEO_NODE_MESH_TOPOLOGY_FACE_OF_CORNER, 0, "FACE_OF_CORNER", FaceOfCorner, "Face of Corner", "Retrieve the face each face corner is part of")
+DefNode(GeometryNode, GEO_NODE_MESH_TOPOLOGY_OFFSET_CORNER_IN_FACE, 0, "OFFSET_CORNER_IN_FACE", OffsetCornerInFace, "Offset Corner in Face", "Retrieve corners in the same face as another")
+DefNode(GeometryNode, GEO_NODE_MESH_TOPOLOGY_VERTEX_OF_CORNER, 0, "VERTEX_OF_CORNER", VertexOfCorner, "Vertex of Corner", "Retrieve the vertex each face corner is attached to")
 DefNode(GeometryNode, GEO_NODE_OBJECT_INFO, def_geo_object_info, "OBJECT_INFO", ObjectInfo, "Object Info", "Retrieve information from an object")
 DefNode(GeometryNode, GEO_NODE_POINTS_TO_VERTICES, 0, "POINTS_TO_VERTICES", PointsToVertices, "Points to Vertices", "Generate a mesh vertex for each point cloud point")
 DefNode(GeometryNode, GEO_NODE_POINTS_TO_VOLUME, def_geo_points_to_volume, "POINTS_TO_VOLUME", PointsToVolume, "Points to Volume", "Generate a fog volume sphere around every point")