Curves: Tweak evaluated offset functions

Add a function to retrieve the points for an index range of curves,
and move "ensuring" the offsets to a separate function, since it's
often nicer to call that if you don't need the result span immediately.

2 files changed, 21 insertions, 3 deletions

diff --git a/source/blender/blenkernel/BKE_curves.hh b/source/blender/blenkernel/BKE_curves.hh
index 6a95bc7d2d2..0f2ae8a02a6 100644
--- a/source/blender/blenkernel/BKE_curves.hh
+++ b/source/blender/blenkernel/BKE_curves.hh
@@ -250,6 +250,7 @@ class CurvesGeometry : public ::CurvesGeometry {
    * Call #evaluated_offsets() first to ensure that the evaluated offsets cache is current.
    */
   IndexRange evaluated_points_for_curve(int index) const;
+  IndexRange evaluated_points_for_curves(IndexRange curves) const;
 
   /**
    * The index of the first evaluated point for every curve. The size of this span is one larger
@@ -258,6 +259,9 @@ class CurvesGeometry : public ::CurvesGeometry {
    */
   Span<int> evaluated_offsets() const;
 
+  /** Makes sure the data described by #evaluated_offsets if necessary. */
+  void ensure_evaluated_offsets() const;
+
   Span<float3> evaluated_positions() const;
 
  private:
diff --git a/source/blender/blenkernel/intern/curves_geometry.cc b/source/blender/blenkernel/intern/curves_geometry.cc
index a069176c6f3..e31a983e0bb 100644
--- a/source/blender/blenkernel/intern/curves_geometry.cc
+++ b/source/blender/blenkernel/intern/curves_geometry.cc
@@ -469,16 +469,25 @@ IndexRange CurvesGeometry::evaluated_points_for_curve(int index) const
   return offsets_to_range(this->runtime->evaluated_offsets_cache.as_span(), index);
 }
 
-Span<int> CurvesGeometry::evaluated_offsets() const
+IndexRange CurvesGeometry::evaluated_points_for_curves(const IndexRange curves) const
+{
+  BLI_assert(!this->runtime->offsets_cache_dirty);
+  BLI_assert(this->curve_size > 0);
+  const int offset = this->runtime->evaluated_offsets_cache[curves.start()];
+  const int offset_next = this->runtime->evaluated_offsets_cache[curves.one_after_last()];
+  return {offset, offset_next - offset};
+}
+
+void CurvesGeometry::ensure_evaluated_offsets() const
 {
   if (!this->runtime->offsets_cache_dirty) {
-    return this->runtime->evaluated_offsets_cache;
+    return;
   }
 
   /* A double checked lock. */
   std::scoped_lock lock{this->runtime->offsets_cache_mutex};
   if (!this->runtime->offsets_cache_dirty) {
-    return this->runtime->evaluated_offsets_cache;
+    return;
   }
 
   threading::isolate_task([&]() {
@@ -496,6 +505,11 @@ Span<int> CurvesGeometry::evaluated_offsets() const
   });
 
   this->runtime->offsets_cache_dirty = false;
+}
+
+Span<int> CurvesGeometry::evaluated_offsets() const
+{
+  this->ensure_evaluated_offsets();
   return this->runtime->evaluated_offsets_cache;
 }