Curves: Port subdivide node to the new data-block

This commit moves the subdivide curve node implementation to the
geometry module, changes it to work on the new curves data-block,
and adds support for Catmull Rom curves. Internally I also added
support for a curve domain selection. That isn't used, but it's
nice to have the option anyway.

Users should notice better performance as well, since we can avoid
many small allocations, and there is no conversion to and from the
old curve type.

The code uses a similar structure to the resample node (60a6fbf5b599)
and the set type node (9e393fc2f125). The resample curves node can be
restructured to be more similar to this soon though.

Differential Revision: https://developer.blender.org/D15334

1 files changed, 15 insertions, 4 deletions

diff --git a/source/blender/blenlib/BLI_index_range.hh b/source/blender/blenlib/BLI_index_range.hh
index 7d5c2400bba..bd0a7e5bb7a 100644
--- a/source/blender/blenlib/BLI_index_range.hh
+++ b/source/blender/blenlib/BLI_index_range.hh
@@ -186,13 +186,15 @@ class IndexRange {
   }
 
   /**
-   * Get the last element in the range.
-   * Asserts when the range is empty.
+   * Get the nth last element in the range.
+   * Asserts when the range is empty or when n is negative.
    */
-  constexpr int64_t last() const
+  constexpr int64_t last(const int64_t n = 0) const
   {
+    BLI_assert(n >= 0);
+    BLI_assert(n < size_);
     BLI_assert(this->size() > 0);
-    return start_ + size_ - 1;
+    return start_ + size_ - 1 - n;
   }
 
   /**
@@ -280,6 +282,15 @@ class IndexRange {
   }
 
   /**
+   * Move the range forward or backward within the larger array. The amount may be negative,
+   * but its absolute value cannot be greater than the existing start of the range.
+   */
+  constexpr IndexRange shift(int64_t n) const
+  {
+    return IndexRange(start_ + n, size_);
+  }
+
+  /**
    * Get read-only access to a memory buffer that contains the range as actual numbers.
    */
   Span<int64_t> as_span() const;