Curves: support sculpting on deformed curves

Previously, curves sculpt tools only worked on original data. This was
very limiting, because one could effectively only sculpt the curves when
all procedural effects were turned off. This patch adds support for curves
sculpting while looking the result of procedural effects (like deformation
based on the surface mesh). This functionality is also known as "crazy space"
support in Blender.

For more details see D15407.

Differential Revision: https://developer.blender.org/D15407

1 files changed, 58 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/geometry_component_edit_data.cc b/source/blender/blenkernel/intern/geometry_component_edit_data.cc
new file mode 100644
index 00000000000..2c00de3254f
--- /dev/null
+++ b/source/blender/blenkernel/intern/geometry_component_edit_data.cc
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "BKE_curves.hh"
+#include "BKE_geometry_set.hh"
+
+using namespace blender;
+using namespace blender::bke;
+
+GeometryComponentEditData::GeometryComponentEditData() : GeometryComponent(GEO_COMPONENT_TYPE_EDIT)
+{
+}
+
+GeometryComponent *GeometryComponentEditData::copy() const
+{
+  GeometryComponentEditData *new_component = new GeometryComponentEditData();
+  if (curves_edit_hints_) {
+    new_component->curves_edit_hints_ = std::make_unique<CurvesEditHints>(*curves_edit_hints_);
+  }
+  return new_component;
+}
+
+bool GeometryComponentEditData::owns_direct_data() const
+{
+  return true;
+}
+
+void GeometryComponentEditData::ensure_owns_direct_data()
+{
+  /* Nothing to do. */
+}
+
+void GeometryComponentEditData::remember_deformed_curve_positions_if_necessary(
+    GeometrySet &geometry)
+{
+  /* This component should be created at the start of object evaluation if it's necessary. */
+  if (!geometry.has<GeometryComponentEditData>()) {
+    return;
+  }
+  GeometryComponentEditData &edit_component =
+      geometry.get_component_for_write<GeometryComponentEditData>();
+  if (!edit_component.curves_edit_hints_) {
+    return;
+  }
+  if (edit_component.curves_edit_hints_->positions.has_value()) {
+    return;
+  }
+  const Curves *curves_id = geometry.get_curves_for_read();
+  if (curves_id == nullptr) {
+    return;
+  }
+  const bke::CurvesGeometry &curves = bke::CurvesGeometry::wrap(curves_id->geometry);
+  const int points_num = curves.points_num();
+  if (points_num != edit_component.curves_edit_hints_->curves_id_orig.geometry.point_num) {
+    return;
+  }
+  edit_component.curves_edit_hints_->positions.emplace(points_num);
+  edit_component.curves_edit_hints_->positions->as_mutable_span().copy_from(curves.positions());
+}