Geometry Nodes: Instance Rotation Node

A field input node for the rotation of each top-level instance transform.
The rotation can be set with the "Rotate Instances" node, but previously
could not be retrieved.

Differential Revision: https://developer.blender.org/D15131

2 files changed, 66 insertions, 0 deletions

diff --git a/source/blender/nodes/geometry/CMakeLists.txt b/source/blender/nodes/geometry/CMakeLists.txt
index 84280c0889a..c3cfd07d4b0 100644
--- a/source/blender/nodes/geometry/CMakeLists.txt
+++ b/source/blender/nodes/geometry/CMakeLists.txt
@@ -71,6 +71,7 @@ set(SRC
   nodes/node_geo_input_curve_tilt.cc
   nodes/node_geo_input_id.cc
   nodes/node_geo_input_index.cc
+  nodes/node_geo_input_instance_rotation.cc
   nodes/node_geo_input_material.cc
   nodes/node_geo_input_material_index.cc
   nodes/node_geo_input_mesh_edge_angle.cc
diff --git a/source/blender/nodes/geometry/nodes/node_geo_input_instance_rotation.cc b/source/blender/nodes/geometry/nodes/node_geo_input_instance_rotation.cc
new file mode 100644
index 00000000000..a6d6722ae2a
--- /dev/null
+++ b/source/blender/nodes/geometry/nodes/node_geo_input_instance_rotation.cc
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "node_geometry_util.hh"
+
+namespace blender::nodes::node_geo_input_instance_rotation_cc {
+
+static void node_declare(NodeDeclarationBuilder &b)
+{
+  b.add_output<decl::Vector>(N_("Rotation")).field_source();
+}
+
+class VectorFieldInput final : public GeometryFieldInput {
+ public:
+  VectorFieldInput() : GeometryFieldInput(CPPType::get<float3>(), "Rotation")
+  {
+  }
+
+  GVArray get_varray_for_context(const GeometryComponent &component,
+                                 const eAttrDomain domain,
+                                 IndexMask mask) const final
+  {
+    if (component.type() != GEO_COMPONENT_TYPE_INSTANCES) {
+      return {};
+    }
+
+    const InstancesComponent &instance_component = static_cast<const InstancesComponent &>(
+        component);
+
+    auto rotation_fn = [&](const int i) -> float3 {
+      return instance_component.instance_transforms()[i].to_euler();
+    };
+
+    return VArray<float3>::ForFunc(instance_component.instances_num(), rotation_fn);
+  }
+
+  uint64_t hash() const override
+  {
+    return 22374372;
+  }
+
+  bool is_equal_to(const fn::FieldNode &other) const override
+  {
+    return dynamic_cast<const VectorFieldInput *>(&other) != nullptr;
+  }
+};
+
+static void node_geo_exec(GeoNodeExecParams params)
+{
+  Field<float3> rotation{std::make_shared<VectorFieldInput>()};
+  params.set_output("Rotation", std::move(rotation));
+}
+
+}  // namespace blender::nodes::node_geo_input_instance_rotation_cc
+
+void register_node_type_geo_input_instance_rotation()
+{
+  namespace file_ns = blender::nodes::node_geo_input_instance_rotation_cc;
+
+  static bNodeType ntype;
+  geo_node_type_base(
+      &ntype, GEO_NODE_INPUT_INSTANCE_ROTATION, "Instance Rotation", NODE_CLASS_INPUT);
+  ntype.geometry_node_execute = file_ns::node_geo_exec;
+  ntype.declare = file_ns::node_declare;
+  nodeRegisterType(&ntype);
+}