Geometry Nodes: Curve Set Spline Type

This node sets the selected (or all) splines in curve to a chosen target
spline type. Poly, Bezier, and NURB splines can be converted to any of
the other types. This is meant to be a building block node, useful in
many procedural situations.

In the future the node could be optimized with multi-threading, or by
avoiding copying in many cases, either by retrieving the curve for write
access or by passing the raw vectors to the new splines where possible.

With edits from Hans Goudey (@HooglyBoogly)

Differential Revision: https://developer.blender.org/D12013

release/scripts/startup/nodeitems_builtins.py

@@ -510,6 +510,7 @@ geometry_node_categories = [
         NodeItem("GeometryNodeCurveTrim"),
         NodeItem("GeometryNodeCurveLength"),
         NodeItem("GeometryNodeCurveReverse"),
+        NodeItem("GeometryNodeCurveSplineType"),
         NodeItem("GeometryNodeCurveSetHandles"),
     ]),
     GeometryNodeCategory("GEO_PRIMITIVES_CURVE", "Curve Primitives", items=[

source/blender/blenkernel/BKE_node.h

@@ -1475,6 +1475,7 @@ int ntreeTexExecTree(struct bNodeTree *ntree,
 #define GEO_NODE_CURVE_PRIMITIVE_QUADRILATERAL 1070
 #define GEO_NODE_CURVE_TRIM 1071
 #define GEO_NODE_CURVE_SET_HANDLES 1072
+#define GEO_NODE_CURVE_SPLINE_TYPE 1073
 
 /** \} */
 

source/blender/blenkernel/intern/node.cc

@@ -5149,6 +5149,7 @@ static void registerGeometryNodes()
   register_node_type_geo_curve_resample();
   register_node_type_geo_curve_reverse();
   register_node_type_geo_curve_set_handles();
+  register_node_type_geo_curve_spline_type();
   register_node_type_geo_curve_subdivide();
   register_node_type_geo_curve_to_mesh();
   register_node_type_geo_curve_to_points();

source/blender/makesdna/DNA_node_types.h

@@ -1355,6 +1355,11 @@ typedef struct NodeSwitch {
   uint8_t input_type;
 } NodeSwitch;
 
+typedef struct NodeGeometryCurveSplineType {
+  /* GeometryNodeSplineType. */
+  uint8_t spline_type;
+} NodeGeometryCurveSplineType;
+
 typedef struct NodeGeometryCurveSetHandles {
   /* GeometryNodeCurveHandleType. */
   uint8_t handle_type;
@@ -1828,6 +1833,12 @@ typedef enum GeometryNodeBooleanOperation {
   GEO_NODE_BOOLEAN_DIFFERENCE = 2,
 } GeometryNodeBooleanOperation;
 
+typedef enum GeometryNodeSplineType {
+  GEO_NODE_SPLINE_TYPE_BEZIER = 0,
+  GEO_NODE_SPLINE_TYPE_NURBS = 1,
+  GEO_NODE_SPLINE_TYPE_POLY = 2,
+} GeometryNodeSplineType;
+
 typedef enum GeometryNodeCurvePrimitiveCircleMode {
   GEO_NODE_CURVE_PRIMITIVE_CIRCLE_TYPE_POINTS = 0,
   GEO_NODE_CURVE_PRIMITIVE_CIRCLE_TYPE_RADIUS = 1

source/blender/makesrna/intern/rna_nodetree.c

@@ -9441,6 +9441,23 @@ static void def_geo_attribute_vector_rotate(StructRNA *srna)
   RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_Node_socket_update");
 }
 
+static void def_geo_curve_spline_type(StructRNA *srna)
+{
+  static const EnumPropertyItem type_items[] = {
+      {GEO_NODE_SPLINE_TYPE_BEZIER, "BEZIER", ICON_NONE, "Bezier", "Set the splines to Bezier"},
+      {GEO_NODE_SPLINE_TYPE_NURBS, "NURBS", ICON_NONE, "NURBS", "Set the splines to NURBS"},
+      {GEO_NODE_SPLINE_TYPE_POLY, "POLY", ICON_NONE, "Poly", "Set the splines to Poly"},
+      {0, NULL, 0, NULL, NULL}};
+
+  PropertyRNA *prop;
+  RNA_def_struct_sdna_from(srna, "NodeGeometryCurveSplineType", "storage");
+
+  prop = RNA_def_property(srna, "spline_type", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_sdna(prop, NULL, "spline_type");
+  RNA_def_property_enum_items(prop, type_items);
+  RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_Node_socket_update");
+}
+
 static void def_geo_curve_set_handles(StructRNA *srna)
 {
   static const EnumPropertyItem type_items[] = {

source/blender/nodes/CMakeLists.txt

@@ -176,6 +176,7 @@ set(SRC
   geometry/nodes/node_geo_curve_resample.cc
   geometry/nodes/node_geo_curve_reverse.cc
   geometry/nodes/node_geo_curve_set_handles.cc
+  geometry/nodes/node_geo_curve_spline_type.cc
   geometry/nodes/node_geo_curve_subdivide.cc
   geometry/nodes/node_geo_curve_to_mesh.cc
   geometry/nodes/node_geo_curve_to_points.cc

source/blender/nodes/NOD_geometry.h

@@ -63,6 +63,7 @@ void register_node_type_geo_curve_primitive_star(void);
 void register_node_type_geo_curve_resample(void);
 void register_node_type_geo_curve_reverse(void);
 void register_node_type_geo_curve_set_handles(void);
+void register_node_type_geo_curve_spline_type(void);
 void register_node_type_geo_curve_subdivide(void);
 void register_node_type_geo_curve_to_mesh(void);
 void register_node_type_geo_curve_to_points(void);

source/blender/nodes/NOD_static_types.h

@@ -303,6 +303,7 @@ DefNode(GeometryNode, GEO_NODE_CURVE_PRIMITIVE_STAR, 0, "CURVE_PRIMITIVE_STAR",
 DefNode(GeometryNode, GEO_NODE_CURVE_RESAMPLE, def_geo_curve_resample, "CURVE_RESAMPLE", CurveResample, "Resample Curve", "")
 DefNode(GeometryNode, GEO_NODE_CURVE_REVERSE, 0, "CURVE_REVERSE", CurveReverse, "Curve Reverse", "")
 DefNode(GeometryNode, GEO_NODE_CURVE_SET_HANDLES, def_geo_curve_set_handles, "CURVE_SET_HANDLES", CurveSetHandles, "Set Handle Type", "")
+DefNode(GeometryNode, GEO_NODE_CURVE_SPLINE_TYPE, def_geo_curve_spline_type, "CURVE_SPLINE_TYPE", CurveSplineType, "Set Spline Type", "")
 DefNode(GeometryNode, GEO_NODE_CURVE_SUBDIVIDE, def_geo_curve_subdivide, "CURVE_SUBDIVIDE", CurveSubdivide, "Curve Subdivide", "")
 DefNode(GeometryNode, GEO_NODE_CURVE_TO_MESH, 0, "CURVE_TO_MESH", CurveToMesh, "Curve to Mesh", "")
 DefNode(GeometryNode, GEO_NODE_CURVE_TO_POINTS, def_geo_curve_to_points, "CURVE_TO_POINTS", CurveToPoints, "Curve to Points", "")

source/blender/nodes/geometry/nodes/node_geo_curve_spline_type.cc

@@ -0,0 +1,307 @@
+/*
+ * 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 "BLI_task.hh"
+
+#include "UI_interface.h"
+#include "UI_resources.h"
+
+#include "node_geometry_util.hh"
+
+static bNodeSocketTemplate geo_node_curve_spline_type_in[] = {
+    {SOCK_GEOMETRY, N_("Curve")},
+    {SOCK_STRING, N_("Selection")},
+    {-1, ""},
+};
+
+static bNodeSocketTemplate geo_node_curve_spline_type_out[] = {
+    {SOCK_GEOMETRY, N_("Curve")},
+    {-1, ""},
+};
+
+static void geo_node_curve_spline_type_layout(uiLayout *layout,
+                                              bContext *UNUSED(C),
+                                              PointerRNA *ptr)
+{
+  uiItemR(layout, ptr, "spline_type", 0, "", ICON_NONE);
+}
+
+namespace blender::nodes {
+
+static void geo_node_curve_spline_type_init(bNodeTree *UNUSED(tree), bNode *node)
+{
+  NodeGeometryCurveSplineType *data = (NodeGeometryCurveSplineType *)MEM_callocN(
+      sizeof(NodeGeometryCurveSplineType), __func__);
+
+  data->spline_type = GEO_NODE_SPLINE_TYPE_POLY;
+  node->storage = data;
+}
+
+template<class T>
+static void scale_input_assign(const Span<T> input,
+                               const int scale,
+                               const int offset,
+                               const MutableSpan<T> r_output)
+{
+  for (const int i : IndexRange(r_output.size())) {
+    r_output[i] = input[i * scale + offset];
+  }
+}
+
+template<class T>
+static void scale_output_assign(const Span<T> input,
+                                const int scale,
+                                const int offset,
+                                const MutableSpan<T> &r_output)
+{
+  for (const int i : IndexRange(input.size())) {
+    r_output[i * scale + offset] = input[i];
+  }
+}
+
+template<typename CopyFn>
+static void copy_attributes(const Spline &input_spline, Spline &output_spline, CopyFn copy_fn)
+{
+  input_spline.attributes.foreach_attribute(
+      [&](StringRefNull name, const AttributeMetaData &meta_data) {
+        std::optional<GSpan> src = input_spline.attributes.get_for_read(name);
+        BLI_assert(src);
+        if (!output_spline.attributes.create(name, meta_data.data_type)) {
+          BLI_assert_unreachable();
+          return false;
+        }
+        std::optional<GMutableSpan> dst = output_spline.attributes.get_for_write(name);
+        if (!dst) {
+          BLI_assert_unreachable();
+          return false;
+        }
+
+        copy_fn(*src, *dst);
+
+        return true;
+      },
+      ATTR_DOMAIN_POINT);
+}
+
+static SplinePtr convert_to_poly_spline(const Spline &input)
+{
+  std::unique_ptr<PolySpline> output = std::make_unique<PolySpline>();
+  output->resize(input.positions().size());
+  output->positions().copy_from(input.positions());
+  output->radii().copy_from(input.radii());
+  output->tilts().copy_from(input.tilts());
+  Spline::copy_base_settings(input, *output);
+  output->attributes = input.attributes;
+  return output;
+}
+
+static SplinePtr poly_to_nurbs(const Spline &input)
+{
+  std::unique_ptr<NURBSpline> output = std::make_unique<NURBSpline>();
+  output->resize(input.positions().size());
+  output->positions().copy_from(input.positions());
+  output->radii().copy_from(input.radii());
+  output->tilts().copy_from(input.tilts());
+  output->weights().fill(1.0f);
+  output->set_resolution(12);
+  output->set_order(4);
+  Spline::copy_base_settings(input, *output);
+  output->knots_mode = NURBSpline::KnotsMode::Bezier;
+  output->attributes = input.attributes;
+  return output;
+}
+
+static SplinePtr bezier_to_nurbs(const Spline &input)
+{
+  const BezierSpline &bezier_spline = static_cast<const BezierSpline &>(input);
+  std::unique_ptr<NURBSpline> output = std::make_unique<NURBSpline>();
+  output->resize(input.size() * 3);
+
+  scale_output_assign(bezier_spline.handle_positions_left(), 3, 0, output->positions());
+  scale_output_assign(input.radii(), 3, 0, output->radii());
+  scale_output_assign(input.tilts(), 3, 0, output->tilts());
+
+  scale_output_assign(bezier_spline.positions(), 3, 1, output->positions());
+  scale_output_assign(input.radii(), 3, 1, output->radii());
+  scale_output_assign(input.tilts(), 3, 1, output->tilts());
+
+  scale_output_assign(bezier_spline.handle_positions_right(), 3, 2, output->positions());
+  scale_output_assign(input.radii(), 3, 2, output->radii());
+  scale_output_assign(input.tilts(), 3, 2, output->tilts());
+
+  Spline::copy_base_settings(input, *output);
+  output->weights().fill(1.0f);
+  output->set_resolution(12);
+  output->set_order(4);
+  output->set_cyclic(input.is_cyclic());
+  output->knots_mode = NURBSpline::KnotsMode::Bezier;
+  output->attributes.reallocate(output->size());
+  copy_attributes(input, *output, [](GSpan src, GMutableSpan dst) {
+    attribute_math::convert_to_static_type(src.type(), [&](auto dummy) {
+      using T = decltype(dummy);
+      scale_output_assign<T>(src.typed<T>(), 3, 0, dst.typed<T>());
+      scale_output_assign<T>(src.typed<T>(), 3, 1, dst.typed<T>());
+      scale_output_assign<T>(src.typed<T>(), 3, 2, dst.typed<T>());
+    });
+  });
+  return output;
+}
+
+static SplinePtr poly_to_bezier(const Spline &input)
+{
+  std::unique_ptr<BezierSpline> output = std::make_unique<BezierSpline>();
+  output->resize(input.size());
+  output->positions().copy_from(input.positions());
+  output->radii().copy_from(input.radii());
+  output->tilts().copy_from(input.tilts());
+  output->handle_types_left().fill(BezierSpline::HandleType::Vector);
+  output->handle_types_right().fill(BezierSpline::HandleType::Vector);
+  output->set_resolution(12);
+  Spline::copy_base_settings(input, *output);
+  output->attributes = input.attributes;
+  return output;
+}
+
+static SplinePtr nurbs_to_bezier(const Spline &input)
+{
+  const NURBSpline &nurbs_spline = static_cast<const NURBSpline &>(input);
+  std::unique_ptr<BezierSpline> output = std::make_unique<BezierSpline>();
+  output->resize(input.size() / 3);
+  scale_input_assign<float3>(input.positions(), 3, 1, output->positions());
+  scale_input_assign<float3>(input.positions(), 3, 0, output->handle_positions_left());
+  scale_input_assign<float3>(input.positions(), 3, 2, output->handle_positions_right());
+  scale_input_assign<float>(input.radii(), 3, 2, output->radii());
+  scale_input_assign<float>(input.tilts(), 3, 2, output->tilts());
+  output->handle_types_left().fill(BezierSpline::HandleType::Align);
+  output->handle_types_right().fill(BezierSpline::HandleType::Align);
+  output->set_resolution(nurbs_spline.resolution());
+  Spline::copy_base_settings(input, *output);
+  output->attributes.reallocate(output->size());
+  copy_attributes(input, *output, [](GSpan src, GMutableSpan dst) {
+    attribute_math::convert_to_static_type(src.type(), [&](auto dummy) {
+      using T = decltype(dummy);
+      scale_input_assign<T>(src.typed<T>(), 3, 1, dst.typed<T>());
+    });
+  });
+  return output;
+}
+
+static SplinePtr convert_to_bezier(const Spline &input, GeoNodeExecParams params)
+{
+  switch (input.type()) {
+    case Spline::Type::Bezier:
+      return input.copy();
+    case Spline::Type::Poly:
+      return poly_to_bezier(input);
+    case Spline::Type::NURBS:
+      if (input.size() < 6) {
+        params.error_message_add(
+            NodeWarningType::Info,
+            TIP_("NURBS must have minimum of 6 points for Bezier Conversion"));
+        return input.copy();
+      }
+      else {
+        if (input.size() % 3 != 0) {
+          params.error_message_add(NodeWarningType::Info,
+                                   TIP_("NURBS must have multiples of 3 points for full Bezier "
+                                        "conversion, curve truncated"));
+        }
+        return nurbs_to_bezier(input);
+      }
+  }
+  BLI_assert_unreachable();
+  return {};
+}
+
+static SplinePtr convert_to_nurbs(const Spline &input)
+{
+  switch (input.type()) {
+    case Spline::Type::NURBS:
+      return input.copy();
+    case Spline::Type::Bezier:
+      return bezier_to_nurbs(input);
+    case Spline::Type::Poly:
+      return poly_to_nurbs(input);
+  }
+  BLI_assert_unreachable();
+  return {};
+}
+
+static void geo_node_curve_spline_type_exec(GeoNodeExecParams params)
+{
+  const NodeGeometryCurveSplineType *storage =
+      (const NodeGeometryCurveSplineType *)params.node().storage;
+  const GeometryNodeSplineType output_type = (const GeometryNodeSplineType)storage->spline_type;
+
+  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;
+  }
+
+  const CurveComponent *curve_component = geometry_set.get_component_for_read<CurveComponent>();
+  const CurveEval &curve = *curve_component->get_for_read();
+
+  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);
+
+  std::unique_ptr<CurveEval> new_curve = std::make_unique<CurveEval>();
+  for (const int i : curve.splines().index_range()) {
+    if (selection[i]) {
+      switch (output_type) {
+        case GEO_NODE_SPLINE_TYPE_POLY:
+          new_curve->add_spline(convert_to_poly_spline(*curve.splines()[i]));
+          break;
+        case GEO_NODE_SPLINE_TYPE_BEZIER:
+          new_curve->add_spline(convert_to_bezier(*curve.splines()[i], params));
+          break;
+        case GEO_NODE_SPLINE_TYPE_NURBS:
+          new_curve->add_spline(convert_to_nurbs(*curve.splines()[i]));
+          break;
+      }
+    }
+    else {
+      new_curve->add_spline(curve.splines()[i]->copy());
+    }
+  }
+
+  new_curve->attributes = curve.attributes;
+  params.set_output("Curve", GeometrySet::create_with_curve(new_curve.release()));
+}
+
+}  // namespace blender::nodes
+
+void register_node_type_geo_curve_spline_type()
+{
+  static bNodeType ntype;
+  geo_node_type_base(
+      &ntype, GEO_NODE_CURVE_SPLINE_TYPE, "Set Spline Type", NODE_CLASS_GEOMETRY, 0);
+  node_type_socket_templates(
+      &ntype, geo_node_curve_spline_type_in, geo_node_curve_spline_type_out);
+  ntype.geometry_node_execute = blender::nodes::geo_node_curve_spline_type_exec;
+  node_type_init(&ntype, blender::nodes::geo_node_curve_spline_type_init);
+  node_type_storage(&ntype,
+                    "NodeGeometryCurveSplineType",
+                    node_free_standard_storage,
+                    node_copy_standard_storage);
+  ntype.draw_buttons = geo_node_curve_spline_type_layout;
+
+  nodeRegisterType(&ntype);
+}