Curves: Avoid duplicating evaluated positions with all poly curves

If all of the curves are poly curves, the evaluated positions are the
same as the original positions. In this case just reuse the original
positions span as the evaluated positions.

2 files changed, 15 insertions, 3 deletions

diff --git a/source/blender/blenkernel/BKE_curves.hh b/source/blender/blenkernel/BKE_curves.hh
index 9dafe2095e7..06971a2243a 100644
--- a/source/blender/blenkernel/BKE_curves.hh
+++ b/source/blender/blenkernel/BKE_curves.hh
@@ -76,6 +76,11 @@ class CurvesGeometryRuntime {
   mutable Vector<float3> evaluated_position_cache;
   mutable std::mutex position_cache_mutex;
   mutable bool position_cache_dirty = true;
+  /**
+   * The evaluated positions result, using a separate span in case all curves are poly curves,
+   * in which case a separate array of evaluated positions is unnecessary.
+   */
+  mutable Span<float3> evaluated_positions_span;
 
   /**
    * Cache of lengths along each evaluated curve for for each evaluated point. If a curve is
diff --git a/source/blender/blenkernel/intern/curves_geometry.cc b/source/blender/blenkernel/intern/curves_geometry.cc
index 5c89dfd4df5..bdd8b3fc3d0 100644
--- a/source/blender/blenkernel/intern/curves_geometry.cc
+++ b/source/blender/blenkernel/intern/curves_geometry.cc
@@ -577,18 +577,25 @@ void CurvesGeometry::ensure_nurbs_basis_cache() const
 Span<float3> CurvesGeometry::evaluated_positions() const
 {
   if (!this->runtime->position_cache_dirty) {
-    return this->runtime->evaluated_position_cache;
+    return this->runtime->evaluated_positions_span;
   }
 
   /* A double checked lock. */
   std::scoped_lock lock{this->runtime->position_cache_mutex};
   if (!this->runtime->position_cache_dirty) {
-    return this->runtime->evaluated_position_cache;
+    return this->runtime->evaluated_positions_span;
   }
 
   threading::isolate_task([&]() {
+    if (this->is_single_type(CURVE_TYPE_POLY)) {
+      this->runtime->evaluated_positions_span = this->positions();
+      this->runtime->evaluated_position_cache.clear_and_make_inline();
+      return;
+    }
+
     this->runtime->evaluated_position_cache.resize(this->evaluated_points_num());
     MutableSpan<float3> evaluated_positions = this->runtime->evaluated_position_cache;
+    this->runtime->evaluated_positions_span = evaluated_positions;
 
     VArray<int8_t> types = this->curve_types();
     VArray<bool> cyclic = this->cyclic();
@@ -645,7 +652,7 @@ Span<float3> CurvesGeometry::evaluated_positions() const
   });
 
   this->runtime->position_cache_dirty = false;
-  return this->runtime->evaluated_position_cache;
+  return this->runtime->evaluated_positions_span;
 }
 
 Span<float3> CurvesGeometry::evaluated_tangents() const