Geometry Nodes: new Scale Elements nodes

This node can scale individual edges and faces. When multiple selected
faces/edges share the same vertices, they are scaled together.
The center and scaling factor is averaged in this case.

For some examples see D13757.

Differential Revision: https://developer.blender.org/D13757

4 files changed, 488 insertions, 0 deletions

diff --git a/source/blender/nodes/NOD_geometry.h b/source/blender/nodes/NOD_geometry.h
index ff4036308c6..9c9e3876662 100644
--- a/source/blender/nodes/NOD_geometry.h
+++ b/source/blender/nodes/NOD_geometry.h
@@ -156,6 +156,7 @@ void register_node_type_geo_raycast(void);
 void register_node_type_geo_realize_instances(void);
 void register_node_type_geo_rotate_instances(void);
 void register_node_type_geo_sample_texture(void);
+void register_node_type_geo_scale_elements(void);
 void register_node_type_geo_scale_instances(void);
 void register_node_type_geo_select_by_handle_type(void);
 void register_node_type_geo_separate_components(void);
diff --git a/source/blender/nodes/NOD_static_types.h b/source/blender/nodes/NOD_static_types.h
index 53d6d64ef84..06a1cf90fca 100644
--- a/source/blender/nodes/NOD_static_types.h
+++ b/source/blender/nodes/NOD_static_types.h
@@ -407,6 +407,7 @@ DefNode(GeometryNode, GEO_NODE_RESAMPLE_CURVE, def_geo_curve_resample, "RESAMPLE
 DefNode(GeometryNode, GEO_NODE_REVERSE_CURVE, 0, "REVERSE_CURVE", ReverseCurve, "Reverse Curve", "")
 DefNode(GeometryNode, GEO_NODE_ROTATE_INSTANCES, 0, "ROTATE_INSTANCES", RotateInstances, "Rotate Instances", "")
 DefNode(GeometryNode, GEO_NODE_SAMPLE_CURVE, def_geo_curve_sample, "SAMPLE_CURVE", SampleCurve, "Sample Curve", "")
+DefNode(GeometryNode, GEO_NODE_SCALE_ELEMENTS, def_geo_scale_elements, "SCALE_ELEMENTS", ScaleElements, "Scale Elements", "")
 DefNode(GeometryNode, GEO_NODE_SCALE_INSTANCES, 0, "SCALE_INSTANCES", ScaleInstances, "Scale Instances", "")
 DefNode(GeometryNode, GEO_NODE_SEPARATE_COMPONENTS, 0, "SEPARATE_COMPONENTS", SeparateComponents, "Separate Components", "")
 DefNode(GeometryNode, GEO_NODE_SEPARATE_GEOMETRY, def_geo_separate_geometry, "SEPARATE_GEOMETRY", SeparateGeometry, "Separate Geometry", "")
diff --git a/source/blender/nodes/geometry/CMakeLists.txt b/source/blender/nodes/geometry/CMakeLists.txt
index 37d7843020a..37b43c26a86 100644
--- a/source/blender/nodes/geometry/CMakeLists.txt
+++ b/source/blender/nodes/geometry/CMakeLists.txt
@@ -167,6 +167,7 @@ set(SRC
   nodes/node_geo_raycast.cc
   nodes/node_geo_realize_instances.cc
   nodes/node_geo_rotate_instances.cc
+  nodes/node_geo_scale_elements.cc
   nodes/node_geo_scale_instances.cc
   nodes/node_geo_separate_components.cc
   nodes/node_geo_separate_geometry.cc
diff --git a/source/blender/nodes/geometry/nodes/node_geo_scale_elements.cc b/source/blender/nodes/geometry/nodes/node_geo_scale_elements.cc
new file mode 100644
index 00000000000..fd599b7ca61
--- /dev/null
+++ b/source/blender/nodes/geometry/nodes/node_geo_scale_elements.cc
@@ -0,0 +1,485 @@
+/*
+ * 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 "BLI_array.hh"
+#include "BLI_disjoint_set.hh"
+#include "BLI_task.hh"
+#include "BLI_vector.hh"
+#include "BLI_vector_set.hh"
+
+#include "DNA_mesh_types.h"
+#include "DNA_meshdata_types.h"
+
+#include "UI_interface.h"
+#include "UI_resources.h"
+
+#include "BKE_mesh.h"
+
+#include "node_geometry_util.hh"
+
+namespace blender::nodes::node_geo_scale_elements_cc {
+
+static void node_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::Geometry>(N_("Geometry")).supported_type(GEO_COMPONENT_TYPE_MESH);
+  b.add_input<decl::Bool>(N_("Selection")).default_value(true).hide_value().supports_field();
+  b.add_input<decl::Float>(N_("Scale"), "Scale").default_value(1.0f).min(0.0f).supports_field();
+  b.add_input<decl::Vector>(N_("Center"))
+      .subtype(PROP_TRANSLATION)
+      .implicit_field()
+      .description(N_("Origin of the scaling for each element. If multiple elements are "
+                      "connected, their center is averaged"));
+  b.add_input<decl::Vector>(N_("Axis"))
+      .default_value({1.0f, 0.0f, 0.0f})
+      .supports_field()
+      .description(N_("Direction in which to scale the element"));
+  b.add_output<decl::Geometry>(N_("Geometry"));
+};
+
+static void node_layout(uiLayout *layout, bContext *UNUSED(C), PointerRNA *ptr)
+{
+  uiItemR(layout, ptr, "domain", 0, "", ICON_NONE);
+  uiItemR(layout, ptr, "scale_mode", 0, "", ICON_NONE);
+}
+
+static void node_init(bNodeTree *UNUSED(tree), bNode *node)
+{
+  node->custom1 = ATTR_DOMAIN_FACE;
+  node->custom2 = GEO_NODE_SCALE_ELEMENTS_UNIFORM;
+}
+
+static void node_update(bNodeTree *ntree, bNode *node)
+{
+  bNodeSocket *geometry_socket = static_cast<bNodeSocket *>(node->inputs.first);
+  bNodeSocket *selection_socket = geometry_socket->next;
+  bNodeSocket *scale_float_socket = selection_socket->next;
+  bNodeSocket *center_socket = scale_float_socket->next;
+  bNodeSocket *axis_socket = center_socket->next;
+
+  const GeometryNodeScaleElementsMode mode = static_cast<GeometryNodeScaleElementsMode>(
+      node->custom2);
+  const bool use_single_axis = mode == GEO_NODE_SCALE_ELEMENTS_SINGLE_AXIS;
+
+  nodeSetSocketAvailability(ntree, axis_socket, use_single_axis);
+}
+
+struct UniformScaleFields {
+  Field<bool> selection;
+  Field<float> scale;
+  Field<float3> center;
+};
+
+struct UniformScaleParams {
+  IndexMask selection;
+  VArray<float> scales;
+  VArray<float3> centers;
+};
+
+struct AxisScaleFields {
+  Field<bool> selection;
+  Field<float> scale;
+  Field<float3> center;
+  Field<float3> axis;
+};
+
+struct AxisScaleParams {
+  IndexMask selection;
+  VArray<float> scales;
+  VArray<float3> centers;
+  VArray<float3> axis_vectors;
+};
+
+/**
+ * When multiple elements share the same vertices, they are scaled together.
+ */
+struct ElementIsland {
+  /* Either face or edge indices. */
+  Vector<int> element_indices;
+};
+
+static float3 transform_with_uniform_scale(const float3 &position,
+                                           const float3 &center,
+                                           const float scale)
+{
+  const float3 diff = position - center;
+  const float3 scaled_diff = scale * diff;
+  const float3 new_position = center + scaled_diff;
+  return new_position;
+}
+
+static float4x4 create_single_axis_transform(const float3 &center,
+                                             const float3 &axis,
+                                             const float scale)
+{
+  /* Scale along x axis. The other axis need to be orthogonal, but their specific value does not
+   * matter. */
+  const float3 x_axis = math::normalize(axis);
+  float3 y_axis = math::cross(x_axis, float3(0.0f, 0.0f, 1.0f));
+  if (math::is_zero(y_axis)) {
+    y_axis = math::cross(x_axis, float3(0.0f, 1.0f, 0.0f));
+  }
+  y_axis = math::normalize(y_axis);
+  const float3 z_axis = math::cross(x_axis, y_axis);
+
+  float4x4 transform = float4x4::identity();
+
+  /* Move scaling center to the origin. */
+  sub_v3_v3(transform.values[3], center);
+
+  /* `base_change` and `base_change_inv` are used to rotate space so that scaling along the
+   * provided axis is the same as scaling along the x axis. */
+  float4x4 base_change = float4x4::identity();
+  copy_v3_v3(base_change.values[0], x_axis);
+  copy_v3_v3(base_change.values[1], y_axis);
+  copy_v3_v3(base_change.values[2], z_axis);
+
+  /* Can invert by transposing, because the matrix is orthonormal. */
+  float4x4 base_change_inv = base_change.transposed();
+
+  float4x4 scale_transform = float4x4::identity();
+  scale_transform.values[0][0] = scale;
+
+  transform = base_change * scale_transform * base_change_inv * transform;
+
+  /* Move scaling center back to where it was. */
+  add_v3_v3(transform.values[3], center);
+
+  return transform;
+}
+
+using GetVertexIndicesFn =
+    FunctionRef<void(const Mesh &mesh, int element_index, VectorSet<int> &r_vertex_indices)>;
+
+static void scale_vertex_islands_uniformly(Mesh &mesh,
+                                           const Span<ElementIsland> islands,
+                                           const UniformScaleParams &params,
+                                           const GetVertexIndicesFn get_vertex_indices)
+{
+  threading::parallel_for(islands.index_range(), 256, [&](const IndexRange range) {
+    for (const int island_index : range) {
+      const ElementIsland &island = islands[island_index];
+
+      float scale = 0.0f;
+      float3 center = {0.0f, 0.0f, 0.0f};
+
+      VectorSet<int> vertex_indices;
+      for (const int poly_index : island.element_indices) {
+        get_vertex_indices(mesh, poly_index, vertex_indices);
+        center += params.centers[poly_index];
+        scale += params.scales[poly_index];
+      }
+
+      /* Divide by number of elements to get the average. */
+      const float f = 1.0f / island.element_indices.size();
+      scale *= f;
+      center *= f;
+
+      for (const int vert_index : vertex_indices) {
+        MVert &vert = mesh.mvert[vert_index];
+        const float3 old_position = vert.co;
+        const float3 new_position = transform_with_uniform_scale(old_position, center, scale);
+        copy_v3_v3(vert.co, new_position);
+      }
+    }
+  });
+
+  /* Positions have changed, so the normals will have to be recomputed. */
+  BKE_mesh_normals_tag_dirty(&mesh);
+}
+
+static void scale_vertex_islands_on_axis(Mesh &mesh,
+                                         const Span<ElementIsland> islands,
+                                         const AxisScaleParams &params,
+                                         const GetVertexIndicesFn get_vertex_indices)
+{
+  threading::parallel_for(islands.index_range(), 256, [&](const IndexRange range) {
+    for (const int island_index : range) {
+      const ElementIsland &island = islands[island_index];
+
+      float scale = 0.0f;
+      float3 center = {0.0f, 0.0f, 0.0f};
+      float3 axis = {0.0f, 0.0f, 0.0f};
+
+      VectorSet<int> vertex_indices;
+      for (const int poly_index : island.element_indices) {
+        get_vertex_indices(mesh, poly_index, vertex_indices);
+        center += params.centers[poly_index];
+        scale += params.scales[poly_index];
+        axis += params.axis_vectors[poly_index];
+      }
+
+      /* Divide by number of elements to get the average. */
+      const float f = 1.0f / island.element_indices.size();
+      scale *= f;
+      center *= f;
+      axis *= f;
+
+      if (math::is_zero(axis)) {
+        axis = float3(1.0f, 0.0f, 0.0f);
+      }
+
+      const float4x4 transform = create_single_axis_transform(center, axis, scale);
+      for (const int vert_index : vertex_indices) {
+        MVert &vert = mesh.mvert[vert_index];
+        const float3 old_position = vert.co;
+        const float3 new_position = transform * old_position;
+        copy_v3_v3(vert.co, new_position);
+      }
+    }
+  });
+
+  /* Positions have changed, so the normals will have to be recomputed. */
+  BKE_mesh_normals_tag_dirty(&mesh);
+}
+
+static Vector<ElementIsland> prepare_face_islands(const Mesh &mesh, const IndexMask face_selection)
+{
+  /* Use the disjoint set data structure to determine which vertices have to be scaled together. */
+  DisjointSet disjoint_set(mesh.totvert);
+  for (const int poly_index : face_selection) {
+    const MPoly &poly = mesh.mpoly[poly_index];
+    const Span<MLoop> poly_loops{mesh.mloop + poly.loopstart, poly.totloop};
+    for (const int loop_index : IndexRange(poly.totloop - 1)) {
+      const int v1 = poly_loops[loop_index].v;
+      const int v2 = poly_loops[loop_index + 1].v;
+      disjoint_set.join(v1, v2);
+    }
+    disjoint_set.join(poly_loops.first().v, poly_loops.last().v);
+  }
+
+  VectorSet<int> island_ids;
+  Vector<ElementIsland> islands;
+  /* There are at most as many islands as there are selected faces. */
+  islands.reserve(face_selection.size());
+
+  /* Gather all of the face indices in each island into separate vectors. */
+  for (const int poly_index : face_selection) {
+    const MPoly &poly = mesh.mpoly[poly_index];
+    const Span<MLoop> poly_loops{mesh.mloop + poly.loopstart, poly.totloop};
+    const int island_id = disjoint_set.find_root(poly_loops[0].v);
+    const int island_index = island_ids.index_of_or_add(island_id);
+    if (island_index == islands.size()) {
+      islands.append_as();
+    }
+    ElementIsland &island = islands[island_index];
+    island.element_indices.append(poly_index);
+  }
+
+  return islands;
+}
+
+static void get_face_vertices(const Mesh &mesh, int face_index, VectorSet<int> &r_vertex_indices)
+{
+  const MPoly &poly = mesh.mpoly[face_index];
+  const Span<MLoop> poly_loops{mesh.mloop + poly.loopstart, poly.totloop};
+  for (const MLoop &loop : poly_loops) {
+    r_vertex_indices.add(loop.v);
+  }
+}
+
+static AxisScaleParams evaluate_axis_scale_fields(FieldEvaluator &evaluator,
+                                                  const AxisScaleFields &fields)
+{
+  AxisScaleParams out;
+  evaluator.set_selection(fields.selection);
+  evaluator.add(fields.scale, &out.scales);
+  evaluator.add(fields.center, &out.centers);
+  evaluator.add(fields.axis, &out.axis_vectors);
+  evaluator.evaluate();
+  out.selection = evaluator.get_evaluated_selection_as_mask();
+  return out;
+}
+
+static void scale_faces_on_axis(MeshComponent &mesh_component, const AxisScaleFields &fields)
+{
+  Mesh &mesh = *mesh_component.get_for_write();
+  mesh.mvert = static_cast<MVert *>(
+      CustomData_duplicate_referenced_layer(&mesh.vdata, CD_MVERT, mesh.totvert));
+
+  GeometryComponentFieldContext field_context{mesh_component, ATTR_DOMAIN_FACE};
+  FieldEvaluator evaluator{field_context, mesh.totpoly};
+  AxisScaleParams params = evaluate_axis_scale_fields(evaluator, fields);
+
+  Vector<ElementIsland> island = prepare_face_islands(mesh, params.selection);
+  scale_vertex_islands_on_axis(mesh, island, params, get_face_vertices);
+}
+
+static UniformScaleParams evaluate_uniform_scale_fields(FieldEvaluator &evaluator,
+                                                        const UniformScaleFields &fields)
+{
+  UniformScaleParams out;
+  evaluator.set_selection(fields.selection);
+  evaluator.add(fields.scale, &out.scales);
+  evaluator.add(fields.center, &out.centers);
+  evaluator.evaluate();
+  out.selection = evaluator.get_evaluated_selection_as_mask();
+  return out;
+}
+
+static void scale_faces_uniformly(MeshComponent &mesh_component, const UniformScaleFields &fields)
+{
+  Mesh &mesh = *mesh_component.get_for_write();
+  mesh.mvert = static_cast<MVert *>(
+      CustomData_duplicate_referenced_layer(&mesh.vdata, CD_MVERT, mesh.totvert));
+
+  GeometryComponentFieldContext field_context{mesh_component, ATTR_DOMAIN_FACE};
+  FieldEvaluator evaluator{field_context, mesh.totpoly};
+  UniformScaleParams params = evaluate_uniform_scale_fields(evaluator, fields);
+
+  Vector<ElementIsland> island = prepare_face_islands(mesh, params.selection);
+  scale_vertex_islands_uniformly(mesh, island, params, get_face_vertices);
+}
+
+static Vector<ElementIsland> prepare_edge_islands(const Mesh &mesh, const IndexMask edge_selection)
+{
+  /* Use the disjoing set data structure to determine which vertices have to be scaled together. */
+  DisjointSet disjoint_set(mesh.totvert);
+  for (const int edge_index : edge_selection) {
+    const MEdge &edge = mesh.medge[edge_index];
+    disjoint_set.join(edge.v1, edge.v2);
+  }
+
+  VectorSet<int> island_ids;
+  Vector<ElementIsland> islands;
+  /* There are at most as many islands as there are selected edges. */
+  islands.reserve(edge_selection.size());
+
+  /* Gather all of the edge indices in each island into separate vectors. */
+  for (const int edge_index : edge_selection) {
+    const MEdge &edge = mesh.medge[edge_index];
+    const int island_id = disjoint_set.find_root(edge.v1);
+    const int island_index = island_ids.index_of_or_add(island_id);
+    if (island_index == islands.size()) {
+      islands.append_as();
+    }
+    ElementIsland &island = islands[island_index];
+    island.element_indices.append(edge_index);
+  }
+
+  return islands;
+}
+
+static void get_edge_vertices(const Mesh &mesh, int edge_index, VectorSet<int> &r_vertex_indices)
+{
+  const MEdge &edge = mesh.medge[edge_index];
+  r_vertex_indices.add(edge.v1);
+  r_vertex_indices.add(edge.v2);
+}
+
+static void scale_edges_uniformly(MeshComponent &mesh_component, const UniformScaleFields &fields)
+{
+  Mesh &mesh = *mesh_component.get_for_write();
+  mesh.mvert = static_cast<MVert *>(
+      CustomData_duplicate_referenced_layer(&mesh.vdata, CD_MVERT, mesh.totvert));
+
+  GeometryComponentFieldContext field_context{mesh_component, ATTR_DOMAIN_EDGE};
+  FieldEvaluator evaluator{field_context, mesh.totedge};
+  UniformScaleParams params = evaluate_uniform_scale_fields(evaluator, fields);
+
+  Vector<ElementIsland> island = prepare_edge_islands(mesh, params.selection);
+  scale_vertex_islands_uniformly(mesh, island, params, get_edge_vertices);
+}
+
+static void scale_edges_on_axis(MeshComponent &mesh_component, const AxisScaleFields &fields)
+{
+  Mesh &mesh = *mesh_component.get_for_write();
+  mesh.mvert = static_cast<MVert *>(
+      CustomData_duplicate_referenced_layer(&mesh.vdata, CD_MVERT, mesh.totvert));
+
+  GeometryComponentFieldContext field_context{mesh_component, ATTR_DOMAIN_EDGE};
+  FieldEvaluator evaluator{field_context, mesh.totedge};
+  AxisScaleParams params = evaluate_axis_scale_fields(evaluator, fields);
+
+  Vector<ElementIsland> island = prepare_edge_islands(mesh, params.selection);
+  scale_vertex_islands_on_axis(mesh, island, params, get_edge_vertices);
+}
+
+static void node_geo_exec(GeoNodeExecParams params)
+{
+  const bNode &node = params.node();
+  const AttributeDomain domain = static_cast<AttributeDomain>(node.custom1);
+  const GeometryNodeScaleElementsMode scale_mode = static_cast<GeometryNodeScaleElementsMode>(
+      node.custom2);
+
+  GeometrySet geometry = params.extract_input<GeometrySet>("Geometry");
+
+  Field<bool> selection_field = params.get_input<Field<bool>>("Selection");
+  Field<float> scale_field = params.get_input<Field<float>>("Scale");
+  Field<float3> center_field = params.get_input<Field<float3>>("Center");
+  Field<float3> axis_field;
+  if (scale_mode == GEO_NODE_SCALE_ELEMENTS_SINGLE_AXIS) {
+    axis_field = params.get_input<Field<float3>>("Axis");
+  }
+
+  geometry.modify_geometry_sets([&](GeometrySet &geometry) {
+    if (!geometry.has_mesh()) {
+      return;
+    }
+    MeshComponent &mesh_component = geometry.get_component_for_write<MeshComponent>();
+    switch (domain) {
+      case ATTR_DOMAIN_FACE: {
+        switch (scale_mode) {
+          case GEO_NODE_SCALE_ELEMENTS_UNIFORM: {
+            scale_faces_uniformly(mesh_component, {selection_field, scale_field, center_field});
+            break;
+          }
+          case GEO_NODE_SCALE_ELEMENTS_SINGLE_AXIS: {
+            scale_faces_on_axis(mesh_component,
+                                {selection_field, scale_field, center_field, axis_field});
+            break;
+          }
+        }
+        break;
+      }
+      case ATTR_DOMAIN_EDGE: {
+        switch (scale_mode) {
+          case GEO_NODE_SCALE_ELEMENTS_UNIFORM: {
+            scale_edges_uniformly(mesh_component, {selection_field, scale_field, center_field});
+            break;
+          }
+          case GEO_NODE_SCALE_ELEMENTS_SINGLE_AXIS: {
+            scale_edges_on_axis(mesh_component,
+                                {selection_field, scale_field, center_field, axis_field});
+            break;
+          }
+        }
+        break;
+      }
+      default:
+        BLI_assert_unreachable();
+        break;
+    }
+  });
+
+  params.set_output("Geometry", std::move(geometry));
+}
+
+}  // namespace blender::nodes::node_geo_scale_elements_cc
+
+void register_node_type_geo_scale_elements()
+{
+  namespace file_ns = blender::nodes::node_geo_scale_elements_cc;
+
+  static bNodeType ntype;
+
+  geo_node_type_base(&ntype, GEO_NODE_SCALE_ELEMENTS, "Scale Elements", NODE_CLASS_GEOMETRY);
+  ntype.geometry_node_execute = file_ns::node_geo_exec;
+  ntype.declare = file_ns::node_declare;
+  ntype.draw_buttons = file_ns::node_layout;
+  ntype.initfunc = file_ns::node_init;
+  ntype.updatefunc = file_ns::node_update;
+  nodeRegisterType(&ntype);
+}