Geometry Nodes: Begin conversion to new curves

This commit changes `CurveComponent` to store the new curve
type by adding conversions to and from `CurveEval` in most nodes.
This will temporarily make performance of curves in geometry nodes
much worse, but as functionality is implemented for the new type
and it is used in more places, performance will become better than
before.

We still use `CurveEval` for drawing curves, because the new `Curves`
data-block has no evaluated points yet. So the `Curve` ID is still
generated for rendering in the same way as before. It's also still
needed for drawing curve object edit mode overlays.

The old curve component isn't removed yet, because it is still used
to implement the conversions to and from `CurveEval`.

A few more attributes are added to make this possible:
- `nurbs_weight`: The weight for each control point on NURBS curves.
- `nurbs_order`: The order of the NURBS curve
- `knots_mode`: Necessary for conversion, not defined yet.
- `handle_type_{left/right}`: An 8 bit integer attribute.

Differential Revision: https://developer.blender.org/D14145

1 files changed, 12 insertions, 9 deletions

diff --git a/source/blender/nodes/geometry/nodes/node_geo_curve_spline_type.cc b/source/blender/nodes/geometry/nodes/node_geo_curve_spline_type.cc
index 053df030f15..d691726da27 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_curve_spline_type.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_curve_spline_type.cc
@@ -367,40 +367,43 @@ static void node_geo_exec(GeoNodeExecParams params)
     }
 
     const CurveComponent *curve_component = geometry_set.get_component_for_read<CurveComponent>();
-    const CurveEval &curve = *curve_component->get_for_read();
+    const std::unique_ptr<CurveEval> curve = curves_to_curve_eval(
+        *curve_component->get_for_read());
     GeometryComponentFieldContext field_context{*curve_component, ATTR_DOMAIN_CURVE};
     const int domain_size = curve_component->attribute_domain_size(ATTR_DOMAIN_CURVE);
 
+    Span<SplinePtr> src_splines = curve->splines();
+
     fn::FieldEvaluator selection_evaluator{field_context, domain_size};
     selection_evaluator.add(selection_field);
     selection_evaluator.evaluate();
     const VArray<bool> &selection = selection_evaluator.get_evaluated<bool>(0);
 
     std::unique_ptr<CurveEval> new_curve = std::make_unique<CurveEval>();
-    new_curve->resize(curve.splines().size());
+    new_curve->resize(src_splines.size());
 
-    threading::parallel_for(curve.splines().index_range(), 512, [&](IndexRange range) {
+    threading::parallel_for(src_splines.index_range(), 512, [&](IndexRange range) {
       for (const int i : range) {
         if (selection[i]) {
           switch (output_type) {
             case GEO_NODE_SPLINE_TYPE_POLY:
-              new_curve->splines()[i] = convert_to_poly_spline(*curve.splines()[i]);
+              new_curve->splines()[i] = convert_to_poly_spline(*src_splines[i]);
               break;
             case GEO_NODE_SPLINE_TYPE_BEZIER:
-              new_curve->splines()[i] = convert_to_bezier(*curve.splines()[i], params);
+              new_curve->splines()[i] = convert_to_bezier(*src_splines[i], params);
               break;
             case GEO_NODE_SPLINE_TYPE_NURBS:
-              new_curve->splines()[i] = convert_to_nurbs(*curve.splines()[i]);
+              new_curve->splines()[i] = convert_to_nurbs(*src_splines[i]);
               break;
           }
         }
         else {
-          new_curve->splines()[i] = curve.splines()[i]->copy();
+          new_curve->splines()[i] = src_splines[i]->copy();
         }
       }
     });
-    new_curve->attributes = curve.attributes;
-    geometry_set.replace_curve(new_curve.release());
+    new_curve->attributes = curve->attributes;
+    geometry_set.replace_curve(curve_eval_to_curves(*new_curve));
   });
 
   params.set_output("Curve", std::move(geometry_set));