Geometry Nodes: Curve Reverse Node

This is an implementation of T88722. It accepts a curve object and
for each spline, reverses the order of the points and all attributes.
This is more of a foundational node to support other nodes in the
future (like curve deform)

Selection takes spline domain attributes to determine which splines
are selected. If no selection is present all splines are reversed.

Differential Revision: https://developer.blender.org/D11538

7 files changed, 134 insertions, 0 deletions

diff --git a/release/scripts/startup/nodeitems_builtins.py b/release/scripts/startup/nodeitems_builtins.py
index 562a676907b..42c0e66aa42 100644
--- a/release/scripts/startup/nodeitems_builtins.py
+++ b/release/scripts/startup/nodeitems_builtins.py
@@ -506,6 +506,7 @@ geometry_node_categories = [
         NodeItem("GeometryNodeMeshToCurve"),
         NodeItem("GeometryNodeCurveToPoints"),
         NodeItem("GeometryNodeCurveLength"),
+        NodeItem("GeometryNodeCurveReverse"),
     ]),
     GeometryNodeCategory("GEO_GEOMETRY", "Geometry", items=[
         NodeItem("GeometryNodeBoundBox"),
diff --git a/source/blender/blenkernel/BKE_node.h b/source/blender/blenkernel/BKE_node.h
index 9401e6a9f02..dbb0786af9d 100644
--- a/source/blender/blenkernel/BKE_node.h
+++ b/source/blender/blenkernel/BKE_node.h
@@ -1435,6 +1435,7 @@ int ntreeTexExecTree(struct bNodeTree *ntree,
 #define GEO_NODE_SELECT_BY_MATERIAL 1055
 #define GEO_NODE_CONVEX_HULL 1056
 #define GEO_NODE_CURVE_TO_POINTS 1057
+#define GEO_NODE_CURVE_REVERSE 1058
 
 /** \} */
 
diff --git a/source/blender/blenkernel/intern/node.cc b/source/blender/blenkernel/intern/node.cc
index 06d70869386..c247b808a4a 100644
--- a/source/blender/blenkernel/intern/node.cc
+++ b/source/blender/blenkernel/intern/node.cc
@@ -5057,6 +5057,7 @@ static void registerGeometryNodes()
   register_node_type_geo_curve_to_mesh();
   register_node_type_geo_curve_to_points();
   register_node_type_geo_curve_resample();
+  register_node_type_geo_curve_reverse();
   register_node_type_geo_delete_geometry();
   register_node_type_geo_edge_split();
   register_node_type_geo_input_material();
diff --git a/source/blender/nodes/CMakeLists.txt b/source/blender/nodes/CMakeLists.txt
index fe705f18fca..9d7c50c99cd 100644
--- a/source/blender/nodes/CMakeLists.txt
+++ b/source/blender/nodes/CMakeLists.txt
@@ -167,6 +167,7 @@ set(SRC
   geometry/nodes/node_geo_curve_to_mesh.cc
   geometry/nodes/node_geo_curve_to_points.cc
   geometry/nodes/node_geo_curve_resample.cc
+  geometry/nodes/node_geo_curve_reverse.cc
   geometry/nodes/node_geo_delete_geometry.cc
   geometry/nodes/node_geo_edge_split.cc
   geometry/nodes/node_geo_input_material.cc
diff --git a/source/blender/nodes/NOD_geometry.h b/source/blender/nodes/NOD_geometry.h
index 1995a42731e..eb3867af155 100644
--- a/source/blender/nodes/NOD_geometry.h
+++ b/source/blender/nodes/NOD_geometry.h
@@ -55,6 +55,7 @@ void register_node_type_geo_curve_length(void);
 void register_node_type_geo_curve_to_mesh(void);
 void register_node_type_geo_curve_to_points(void);
 void register_node_type_geo_curve_resample(void);
+void register_node_type_geo_curve_reverse(void);
 void register_node_type_geo_delete_geometry(void);
 void register_node_type_geo_edge_split(void);
 void register_node_type_geo_input_material(void);
diff --git a/source/blender/nodes/NOD_static_types.h b/source/blender/nodes/NOD_static_types.h
index edf516b7388..8ae1fab87ff 100644
--- a/source/blender/nodes/NOD_static_types.h
+++ b/source/blender/nodes/NOD_static_types.h
@@ -293,6 +293,7 @@ DefNode(GeometryNode, GEO_NODE_CONVEX_HULL, 0, "CONVEX_HULL", ConvexHull, "Conve
 DefNode(GeometryNode, GEO_NODE_CURVE_LENGTH, 0, "CURVE_LENGTH", CurveLength, "Curve Length", "")
 DefNode(GeometryNode, GEO_NODE_CURVE_RESAMPLE, def_geo_curve_resample, "CURVE_RESAMPLE", CurveResample, "Resample Curve", "")
 DefNode(GeometryNode, GEO_NODE_CURVE_TO_MESH, 0, "CURVE_TO_MESH", CurveToMesh, "Curve to Mesh", "")
+DefNode(GeometryNode, GEO_NODE_CURVE_REVERSE, 0, "CURVE_REVERSE", CurveReverse, "Curve Reverse", "")
 DefNode(GeometryNode, GEO_NODE_CURVE_TO_POINTS, def_geo_curve_to_points, "CURVE_TO_POINTS", CurveToPoints, "Curve to Points", "")
 DefNode(GeometryNode, GEO_NODE_DELETE_GEOMETRY, 0, "DELETE_GEOMETRY", DeleteGeometry, "Delete Geometry", "")
 DefNode(GeometryNode, GEO_NODE_EDGE_SPLIT, 0, "EDGE_SPLIT", EdgeSplit, "Edge Split", "")
diff --git a/source/blender/nodes/geometry/nodes/node_geo_curve_reverse.cc b/source/blender/nodes/geometry/nodes/node_geo_curve_reverse.cc
new file mode 100644
index 00000000000..f268f3f7ff1
--- /dev/null
+++ b/source/blender/nodes/geometry/nodes/node_geo_curve_reverse.cc
@@ -0,0 +1,128 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include "BKE_spline.hh"
+
+#include "node_geometry_util.hh"
+
+static bNodeSocketTemplate geo_node_curve_reverse_in[] = {
+    {SOCK_GEOMETRY, N_("Curve")},
+    {SOCK_STRING, N_("Selection")},
+    {-1, ""},
+};
+
+static bNodeSocketTemplate geo_node_curve_reverse_out[] = {
+    {SOCK_GEOMETRY, N_("Curve")},
+    {-1, ""},
+};
+
+namespace blender::nodes {
+
+/**
+ * Reverse the data in a MutableSpan object.
+ */
+template<typename T> static void reverse_data(MutableSpan<T> r_data)
+{
+  const int size = r_data.size();
+  for (const int i : IndexRange(size / 2)) {
+    std::swap(r_data[size - 1 - i], r_data[i]);
+  }
+}
+
+/**
+ * Reverse and Swap the data between 2 MutableSpans.
+ */
+template<typename T> static void reverse_data(MutableSpan<T> left, MutableSpan<T> right)
+{
+  BLI_assert(left.size() == right.size());
+  const int size = left.size();
+
+  for (const int i : IndexRange(size / 2 + size % 2)) {
+    std::swap(left[i], right[size - 1 - i]);
+    std::swap(right[i], left[size - 1 - i]);
+  }
+}
+
+static void geo_node_curve_reverse_exec(GeoNodeExecParams params)
+{
+  GeometrySet geometry_set = params.extract_input<GeometrySet>("Curve");
+  geometry_set = bke::geometry_set_realize_instances(geometry_set);
+  if (!geometry_set.has_curve()) {
+    params.set_output("Curve", geometry_set);
+    return;
+  }
+
+  /* Retrieve data for write access so we can avoid new allocations for the reversed data. */
+  CurveComponent &curve_component = geometry_set.get_component_for_write<CurveComponent>();
+  CurveEval &curve = *curve_component.get_for_write();
+  MutableSpan<SplinePtr> splines = curve.splines();
+
+  const std::string selection_name = params.extract_input<std::string>("Selection");
+  GVArray_Typed<bool> selection = curve_component.attribute_get_for_read(
+      selection_name, ATTR_DOMAIN_CURVE, true);
+
+  for (const int i : splines.index_range()) {
+    if (!selection[i]) {
+      continue;
+    }
+
+    reverse_data<float3>(splines[i]->positions());
+    reverse_data<float>(splines[i]->radii());
+    reverse_data<float>(splines[i]->tilts());
+
+    splines[i]->attributes.foreach_attribute(
+        [&](StringRefNull name, const AttributeMetaData &meta_data) {
+          std::optional<blender::fn::GMutableSpan> output_attribute =
+              splines[i]->attributes.get_for_write(name);
+          if (!output_attribute) {
+            BLI_assert_unreachable();
+            return false;
+          }
+          attribute_math::convert_to_static_type(meta_data.data_type, [&](auto dummy) {
+            using T = decltype(dummy);
+            reverse_data(output_attribute->typed<T>());
+          });
+          return true;
+        },
+        ATTR_DOMAIN_POINT);
+
+    /* Deal with extra info on derived types. */
+    if (BezierSpline *spline = dynamic_cast<BezierSpline *>(splines[i].get())) {
+      reverse_data<BezierSpline::HandleType>(spline->handle_types_left());
+      reverse_data<BezierSpline::HandleType>(spline->handle_types_right());
+      reverse_data<float3>(spline->handle_positions_left(), spline->handle_positions_right());
+    }
+    else if (NURBSpline *spline = dynamic_cast<NURBSpline *>(splines[i].get())) {
+      reverse_data<float>(spline->weights());
+    }
+    /* Nothing to do for poly splines. */
+
+    splines[i]->mark_cache_invalid();
+  }
+
+  params.set_output("Curve", geometry_set);
+}
+
+}  // namespace blender::nodes
+
+void register_node_type_geo_curve_reverse()
+{
+  static bNodeType ntype;
+  geo_node_type_base(&ntype, GEO_NODE_CURVE_REVERSE, "Curve Reverse", NODE_CLASS_GEOMETRY, 0);
+  node_type_socket_templates(&ntype, geo_node_curve_reverse_in, geo_node_curve_reverse_out);
+  ntype.geometry_node_execute = blender::nodes::geo_node_curve_reverse_exec;
+  nodeRegisterType(&ntype);
+}