WIP: Curves: Basic custom normals support

@@ -160,2 +160,4 @@
    */
   Span<float> nurbs_weight;
+
+  Span<float3> custom_normal;

@@ -1359,1 +1380,4 @@
 
+  if (all_curves_info.create_custom_normal_attribute) {
+    if (curves_info.custom_normal.is_empty()) {
+      all_handle_right.slice(dst_point_range).fill(float3(0, 0, 1));

@@ -1360,0 +1383,4 @@
+      all_handle_right.slice(dst_point_range).fill(float3(0, 0, 1));
+    }
+    else {
+      copy_transformed_directions(

@@ -23,1 +23,4 @@
   b.add_input<decl::Bool>("Selection").default_value(true).hide_value().field_on_all();
+  if (const bNode *node = b.node_or_null()) {
+    if (node->custom1 == NORMAL_MODE_CUSTOM) {
+      b.add_input<decl::Vector>("Normal").default_value({0.0f, 0.0f, 1.0f}).field_on_all();

@@ -1057,6 +1078,16 @@ static void transform_positions(MutableSpan<float3> positions, const float4x4 &m
   });
 }
 
+static void transform_directions(MutableSpan<float3> directions, const float4x4 &matrix)

@@ -293,6 +298,23 @@ static void copy_transformed_positions(const Span<float3> src,
   });
 }
 
+static void copy_transformed_directions(const Span<float3> src,

@@ -296,0 +309,4 @@
+  else {
+    threading::parallel_for(src.index_range(), 1024, [&](const IndexRange range) {
+      for (const int i : range) {
+        dst[i] = math::transform_direction(normal_transform, src[i]);