[Bf-blender-cvs] [f973e0b75a7] master: Fix: Spline length calculation fails with no evaluated points

[Hans Goudey]

Commit: f973e0b75a79ef6b05677e36d41fdeff70ea6d9d
Author: Hans Goudey
Date:   Sun Sep 19 19:00:50 2021 -0500
Branches: master
https://developer.blender.org/rBf973e0b75a79ef6b05677e36d41fdeff70ea6d9d

Fix: Spline length calculation fails with no evaluated points

The case that checked whether there were evaluated edges was incorrect,
since two points are needed for an edge. Then also avoid running the
accumulation for an empty span.

===================================================================

M	source/blender/blenkernel/intern/spline_base.cc

===================================================================

diff --git a/source/blender/blenkernel/intern/spline_base.cc b/source/blender/blenkernel/intern/spline_base.cc
index 807019f60a8..663c1951ba3 100644
--- a/source/blender/blenkernel/intern/spline_base.cc
+++ b/source/blender/blenkernel/intern/spline_base.cc
@@ -142,7 +142,8 @@ void Spline::reverse()
 int Spline::evaluated_edges_size() const
 {
   const int eval_size = this->evaluated_points_size();
-  if (eval_size == 1) {
+  if (eval_size < 2) {
+    /* Two points are required for an edge. */
     return 0;
   }
 
@@ -205,9 +206,10 @@ Span<float> Spline::evaluated_lengths() const
 
   const int total = evaluated_edges_size();
   evaluated_lengths_cache_.resize(total);
-
-  Span<float3> positions = this->evaluated_positions();
-  accumulate_lengths(positions, is_cyclic_, evaluated_lengths_cache_);
+  if (total != 0) {
+    Span<float3> positions = this->evaluated_positions();
+    accumulate_lengths(positions, is_cyclic_, evaluated_lengths_cache_);
+  }
 
   length_cache_dirty_ = false;
   return evaluated_lengths_cache_;