Geometry Nodes: Rotate Instances Node

Adds a node that can rotate each of a geometry's instances in global
(to the modifier object) or local space (of each point) by a specified
angle around a pivot point.

In the future, separating the local-global choice for the pivot and the
rotation might be useful. However, for now the node is kept simple.

Differential Revision: https://developer.blender.org/D12682

6 files changed, 104 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_node.h b/source/blender/blenkernel/BKE_node.h
index 4c1c49555b8..b83d8d0e5e6 100644
--- a/source/blender/blenkernel/BKE_node.h
+++ b/source/blender/blenkernel/BKE_node.h
@@ -1534,6 +1534,7 @@ int ntreeTexExecTree(struct bNodeTree *ntree,
 #define GEO_NODE_SET_MATERIAL_INDEX 1119
 #define GEO_NODE_TRANSLATE_INSTANCES 1120
 #define GEO_NODE_SCALE_INSTANCES 1121
+#define GEO_NODE_ROTATE_INSTANCES 1122
 
 /** \} */
 
diff --git a/source/blender/blenkernel/intern/node.cc b/source/blender/blenkernel/intern/node.cc
index 283e28ed54f..16435ea6c58 100644
--- a/source/blender/blenkernel/intern/node.cc
+++ b/source/blender/blenkernel/intern/node.cc
@@ -5809,6 +5809,7 @@ static void registerGeometryNodes()
   register_node_type_geo_proximity();
   register_node_type_geo_raycast();
   register_node_type_geo_realize_instances();
+  register_node_type_geo_rotate_instances();
   register_node_type_geo_sample_texture();
   register_node_type_geo_scale_instances();
   register_node_type_geo_separate_components();
diff --git a/source/blender/nodes/CMakeLists.txt b/source/blender/nodes/CMakeLists.txt
index e543db92b9f..19740a973a2 100644
--- a/source/blender/nodes/CMakeLists.txt
+++ b/source/blender/nodes/CMakeLists.txt
@@ -253,6 +253,7 @@ set(SRC
   geometry/nodes/node_geo_points_to_volume.cc
   geometry/nodes/node_geo_proximity.cc
   geometry/nodes/node_geo_realize_instances.cc
+  geometry/nodes/node_geo_rotate_instances.cc
   geometry/nodes/node_geo_scale_instances.cc
   geometry/nodes/node_geo_separate_components.cc
   geometry/nodes/node_geo_separate_geometry.cc
diff --git a/source/blender/nodes/NOD_geometry.h b/source/blender/nodes/NOD_geometry.h
index 3b0816300f5..f9b3c5ee09a 100644
--- a/source/blender/nodes/NOD_geometry.h
+++ b/source/blender/nodes/NOD_geometry.h
@@ -129,6 +129,7 @@ void register_node_type_geo_points_to_volume(void);
 void register_node_type_geo_proximity(void);
 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_instances(void);
 void register_node_type_geo_select_by_handle_type(void);
diff --git a/source/blender/nodes/NOD_static_types.h b/source/blender/nodes/NOD_static_types.h
index 010327a1ac1..813e97be044 100644
--- a/source/blender/nodes/NOD_static_types.h
+++ b/source/blender/nodes/NOD_static_types.h
@@ -381,6 +381,7 @@ DefNode(GeometryNode, GEO_NODE_POINTS_TO_VERTICES, 0, "POINTS_TO_VERTICES", Poin
 DefNode(GeometryNode, GEO_NODE_POINTS_TO_VOLUME, def_geo_points_to_volume, "POINTS_TO_VOLUME", PointsToVolume, "Points to Volume", "")
 DefNode(GeometryNode, GEO_NODE_PROXIMITY, def_geo_proximity, "PROXIMITY", Proximity, "Geometry Proximity", "")
 DefNode(GeometryNode, GEO_NODE_REALIZE_INSTANCES, 0, "REALIZE_INSTANCES", RealizeInstances, "Realize Instances", "")
+DefNode(GeometryNode, GEO_NODE_ROTATE_INSTANCES, 0, "ROTATE_INSTANCES", RotateInstances, "Rotate Instances", "")
 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/nodes/node_geo_rotate_instances.cc b/source/blender/nodes/geometry/nodes/node_geo_rotate_instances.cc
new file mode 100644
index 00000000000..09d92d7fa1e
--- /dev/null
+++ b/source/blender/nodes/geometry/nodes/node_geo_rotate_instances.cc
@@ -0,0 +1,99 @@
+/*
+ * 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_task.hh"
+
+#include "node_geometry_util.hh"
+
+namespace blender::nodes {
+
+static void geo_node_rotate_instances_declare(NodeDeclarationBuilder &b)
+{
+  b.add_input<decl::Geometry>("Geometry");
+  b.add_input<decl::Bool>("Selection").default_value(true).hide_value().supports_field();
+  b.add_input<decl::Vector>("Rotation").subtype(PROP_EULER).supports_field();
+  b.add_input<decl::Vector>("Pivot Point").subtype(PROP_TRANSLATION).supports_field();
+  b.add_input<decl::Bool>("Local Space").default_value(true).supports_field();
+  b.add_output<decl::Geometry>("Geometry");
+};
+
+static void rotate_instances(GeoNodeExecParams &params, InstancesComponent &instances_component)
+{
+  GeometryComponentFieldContext field_context{instances_component, ATTR_DOMAIN_POINT};
+  const int domain_size = instances_component.instances_amount();
+
+  fn::FieldEvaluator selection_evaluator{field_context, domain_size};
+  selection_evaluator.add(params.extract_input<Field<bool>>("Selection"));
+  selection_evaluator.evaluate();
+  const IndexMask selection = selection_evaluator.get_evaluated_as_mask(0);
+
+  fn::FieldEvaluator transforms_evaluator{field_context, &selection};
+  transforms_evaluator.add(params.extract_input<Field<float3>>("Rotation"));
+  transforms_evaluator.add(params.extract_input<Field<float3>>("Pivot Point"));
+  transforms_evaluator.add(params.extract_input<Field<bool>>("Local Space"));
+  transforms_evaluator.evaluate();
+  const VArray<float3> &rotations = transforms_evaluator.get_evaluated<float3>(0);
+  const VArray<float3> &pivots = transforms_evaluator.get_evaluated<float3>(1);
+  const VArray<bool> &local_spaces = transforms_evaluator.get_evaluated<bool>(2);
+
+  MutableSpan<float4x4> instance_transforms = instances_component.instance_transforms();
+
+  threading::parallel_for(selection.index_range(), 512, [&](IndexRange range) {
+    for (const int i_selection : range) {
+      const int i = selection[i_selection];
+      const float3 pivot = pivots[i];
+      float4x4 &instance_transform = instance_transforms[i];
+      const float4x4 rotation_matrix = float4x4::from_loc_eul_scale(
+          {0, 0, 0}, rotations[i], {1, 1, 1});
+
+      if (local_spaces[i]) {
+        instance_transform *= float4x4::from_location(pivot);
+        instance_transform *= rotation_matrix;
+        instance_transform *= float4x4::from_location(-pivot);
+      }
+      else {
+        const float4x4 orgiginal_transform = instance_transform;
+        instance_transform = float4x4::from_location(pivot);
+        instance_transform *= rotation_matrix;
+        instance_transform *= float4x4::from_location(-pivot);
+        instance_transform *= orgiginal_transform;
+      }
+    }
+  });
+}
+
+static void geo_node_rotate_instances_exec(GeoNodeExecParams params)
+{
+  GeometrySet geometry_set = params.extract_input<GeometrySet>("Geometry");
+  if (geometry_set.has_instances()) {
+    InstancesComponent &instances = geometry_set.get_component_for_write<InstancesComponent>();
+    rotate_instances(params, instances);
+  }
+  params.set_output("Geometry", std::move(geometry_set));
+}
+
+}  // namespace blender::nodes
+
+void register_node_type_geo_rotate_instances()
+{
+  static bNodeType ntype;
+
+  geo_node_type_base(
+      &ntype, GEO_NODE_ROTATE_INSTANCES, "Rotate Instances", NODE_CLASS_GEOMETRY, 0);
+  ntype.geometry_node_execute = blender::nodes::geo_node_rotate_instances_exec;
+  ntype.declare = blender::nodes::geo_node_rotate_instances_declare;
+  nodeRegisterType(&ntype);
+}