Raycast geometry node.

The //Raycast// node intersects rays from one geometry onto another.
It computes hit points on the target mesh and returns normals, distances
and any surface attribute specified by the user.

A ray starts on each point of the input //Geometry//. Rays continue
in the //Ray Direction// until they either hit the //Target Geometry//
or reach the //Ray Length// limit. If the target is hit, the value of the
//Is Hit// attribute in the output mesh will be true. //Hit Position//,
//Hit Normal//, //Hit Distance// and //Hit Index// are the properties of the
target mesh at the intersection point. In addition, a //Target Attribute//
can be specified that is interpolated at the hit point and the result
stored in //Hit Attribute//.

Docs: D11620

Reviewed By: HooglyBoogly

Differential Revision: https://developer.blender.org/D11619

1 files changed, 42 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_mesh_sample.hh b/source/blender/blenkernel/BKE_mesh_sample.hh
index f504650e349..c40d2e947e3 100644
--- a/source/blender/blenkernel/BKE_mesh_sample.hh
+++ b/source/blender/blenkernel/BKE_mesh_sample.hh
@@ -28,6 +28,11 @@
 
 struct Mesh;
 
+namespace blender::bke {
+struct ReadAttributeLookup;
+class OutputAttribute;
+}  // namespace blender::bke
+
 namespace blender::bke::mesh_surface_sample {
 
 using fn::CPPType;
@@ -35,6 +40,8 @@ using fn::GMutableSpan;
 using fn::GSpan;
 using fn::GVArray;
 
+Span<MLoopTri> get_mesh_looptris(const Mesh &mesh);
+
 void sample_point_attribute(const Mesh &mesh,
                             Span<int> looptri_indices,
                             Span<float3> bary_coords,
@@ -52,4 +59,39 @@ void sample_face_attribute(const Mesh &mesh,
                            const GVArray &data_in,
                            GMutableSpan data_out);
 
+enum class eAttributeMapMode {
+  INTERPOLATED,
+  NEAREST,
+};
+
+/**
+ * A utility class that performs attribute interpolation from a source mesh.
+ *
+ * The interpolator is only valid as long as the mesh is valid.
+ * Barycentric weights are needed when interpolating point or corner domain attributes,
+ * these are computed lazily when needed and re-used.
+ */
+class MeshAttributeInterpolator {
+ private:
+  const Mesh *mesh_;
+  const Span<float3> positions_;
+  const Span<int> looptri_indices_;
+
+  Array<float3> bary_coords_;
+  Array<float3> nearest_weights_;
+
+ public:
+  MeshAttributeInterpolator(const Mesh *mesh,
+                        const Span<float3> positions,
+                        const Span<int> looptri_indices);
+
+  void sample_attribute(const ReadAttributeLookup &src_attribute,
+                        OutputAttribute &dst_attribute,
+                        eAttributeMapMode mode);
+
+ protected:
+  Span<float3> ensure_barycentric_coords();
+  Span<float3> ensure_nearest_weights();
+};
+
 }  // namespace blender::bke::mesh_surface_sample