Geometry Nodes: Port the trim curve node to the new data-block

The trim functionality is implemented in the geometry module, and
generalized a bit to be potentially useful for bisecting in the future.
The implementation is based on a helper type called `IndexRangeCyclic`
which allows iteration over all control points between two points on a
curve.

Catmull Rom curves are now supported-- trimmed without resampling first.
However, maintaining the exact shape is not possible. NURBS splines are
still converted to polylines using the evaluated curve concept.

Performance is equivalent or faster then a 3.1 build with regards to
node timings. Compared to 3.3 and 3.2, it's easy to observe test cases
where the node is at least 3 or 4 times faster.

Differential Revision: https://developer.blender.org/D14481

1 files changed, 6 insertions, 8 deletions

diff --git a/source/blender/blenkernel/intern/curve_catmull_rom.cc b/source/blender/blenkernel/intern/curve_catmull_rom.cc
index 952d59edcf9..dac88948036 100644
--- a/source/blender/blenkernel/intern/curve_catmull_rom.cc
+++ b/source/blender/blenkernel/intern/curve_catmull_rom.cc
@@ -17,16 +17,14 @@ int calculate_evaluated_num(const int points_num, const bool cyclic, const int r
 }
 
 /* Adapted from Cycles #catmull_rom_basis_eval function. */
-template<typename T>
-static T calculate_basis(const T &a, const T &b, const T &c, const T &d, const float parameter)
+void calculate_basis(const float parameter, float r_weights[4])
 {
   const float t = parameter;
   const float s = 1.0f - parameter;
-  const float n0 = -t * s * s;
-  const float n1 = 2.0f + t * t * (3.0f * t - 5.0f);
-  const float n2 = 2.0f + s * s * (3.0f * s - 5.0f);
-  const float n3 = -s * t * t;
-  return 0.5f * (a * n0 + b * n1 + c * n2 + d * n3);
+  r_weights[0] = -t * s * s;
+  r_weights[1] = 2.0f + t * t * (3.0f * t - 5.0f);
+  r_weights[2] = 2.0f + s * s * (3.0f * s - 5.0f);
+  r_weights[3] = -s * t * t;
 }
 
 template<typename T>
@@ -35,7 +33,7 @@ static void evaluate_segment(const T &a, const T &b, const T &c, const T &d, Mut
   const float step = 1.0f / dst.size();
   dst.first() = b;
   for (const int i : dst.index_range().drop_front(1)) {
-    dst[i] = calculate_basis<T>(a, b, c, d, i * step);
+    dst[i] = interpolate<T>(a, b, c, d, i * step);
   }
 }