Geometry Nodes: new Align Rotation to Vector node

This adds a new Align Rotation to Vector node based on the mockup
in T83669.

Reviewers: HooglyBoogly, simonthommes

Differential Revision: https://developer.blender.org/D10081

4 files changed, 152 insertions, 0 deletions

diff --git a/source/blender/nodes/CMakeLists.txt b/source/blender/nodes/CMakeLists.txt
index de4d23d8577..64667faa735 100644
--- a/source/blender/nodes/CMakeLists.txt
+++ b/source/blender/nodes/CMakeLists.txt
@@ -140,6 +140,7 @@ set(SRC
   function/nodes/node_fn_switch.cc
   function/node_function_util.cc
 
+  geometry/nodes/node_geo_align_rotation_to_vector.cc
   geometry/nodes/node_geo_attribute_color_ramp.cc
   geometry/nodes/node_geo_attribute_compare.cc
   geometry/nodes/node_geo_attribute_fill.cc
diff --git a/source/blender/nodes/NOD_geometry.h b/source/blender/nodes/NOD_geometry.h
index 93123c9a684..4cd9bce1b9d 100644
--- a/source/blender/nodes/NOD_geometry.h
+++ b/source/blender/nodes/NOD_geometry.h
@@ -44,6 +44,7 @@ void register_node_type_geo_attribute_compare(void);
 void register_node_type_geo_attribute_mix(void);
 void register_node_type_geo_attribute_color_ramp(void);
 void register_node_type_geo_rotate_points(void);
+void register_node_type_geo_align_rotation_to_vector(void);
 
 #ifdef __cplusplus
 }
diff --git a/source/blender/nodes/NOD_static_types.h b/source/blender/nodes/NOD_static_types.h
index 55b06cb31a5..8eeb179ed0d 100644
--- a/source/blender/nodes/NOD_static_types.h
+++ b/source/blender/nodes/NOD_static_types.h
@@ -286,6 +286,7 @@ DefNode(GeometryNode, GEO_NODE_POINT_SEPARATE, 0, "POINT_SEPARATE", PointSeparat
 DefNode(GeometryNode, GEO_NODE_ATTRIBUTE_COMPARE, def_geo_attribute_attribute_compare, "ATTRIBUTE_COMPARE", AttributeCompare, "Attribute Compare", "")
 DefNode(GeometryNode, GEO_NODE_ROTATE_POINTS, def_geo_rotate_points, "ROTATE_POINTS", RotatePoints, "Rotate Points", "")
 DefNode(GeometryNode, GEO_NODE_ATTRIBUTE_VECTOR_MATH, def_geo_attribute_vector_math, "ATTRIBUTE_VECTOR_MATH", AttributeVectorMath, "Attribute Vector Math", "")
+DefNode(GeometryNode, GEO_NODE_ALIGN_ROTATION_TO_VECTOR, def_geo_align_rotation_to_vector, "ALIGN_ROTATION_TO_VECTOR", AlignRotationToVector, "Align Rotation to Vector", "")
 
 /* undefine macros */
 #undef DefNode
diff --git a/source/blender/nodes/geometry/nodes/node_geo_align_rotation_to_vector.cc b/source/blender/nodes/geometry/nodes/node_geo_align_rotation_to_vector.cc
new file mode 100644
index 00000000000..c38f54ce7f7
--- /dev/null
+++ b/source/blender/nodes/geometry/nodes/node_geo_align_rotation_to_vector.cc
@@ -0,0 +1,149 @@
+/*
+ * 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 "node_geometry_util.hh"
+
+#include "BLI_math_rotation.h"
+
+static bNodeSocketTemplate geo_node_align_rotation_to_vector_in[] = {
+    {SOCK_GEOMETRY, N_("Geometry")},
+    {SOCK_STRING, N_("Factor")},
+    {SOCK_FLOAT, N_("Factor"), 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, PROP_FACTOR},
+    {SOCK_STRING, N_("Vector")},
+    {SOCK_VECTOR, N_("Vector"), 0.0, 0.0, 1.0, 0.0, -FLT_MAX, FLT_MAX, PROP_ANGLE},
+    {-1, ""},
+};
+
+static bNodeSocketTemplate geo_node_align_rotation_to_vector_out[] = {
+    {SOCK_GEOMETRY, N_("Geometry")},
+    {-1, ""},
+};
+
+namespace blender::nodes {
+
+static void align_rotations_on_component(GeometryComponent &component,
+                                         const GeoNodeExecParams &params)
+{
+  const bNode &node = params.node();
+  const NodeGeometryAlignRotationToVector &storage = *(const NodeGeometryAlignRotationToVector *)
+                                                          node.storage;
+
+  WriteAttributePtr rotation_attribute = component.attribute_try_ensure_for_write(
+      "rotation", ATTR_DOMAIN_POINT, CD_PROP_FLOAT3);
+  if (!rotation_attribute) {
+    return;
+  }
+  MutableSpan<float3> rotations = rotation_attribute->get_span().typed<float3>();
+
+  FloatReadAttribute factors = params.get_input_attribute<float>(
+      "Factor", component, ATTR_DOMAIN_POINT, 1.0f);
+  Float3ReadAttribute vectors = params.get_input_attribute<float3>(
+      "Vector", component, ATTR_DOMAIN_POINT, {0, 0, 1});
+
+  float3 main_axis{0, 0, 0};
+  main_axis[storage.axis] = 1;
+
+  const int domain_size = component.attribute_domain_size(ATTR_DOMAIN_POINT);
+  for (const int i : IndexRange(domain_size)) {
+    const float3 vector = vectors[i];
+    if (is_zero_v3(vector)) {
+      continue;
+    }
+
+    float old_rotation[3][3];
+    eul_to_mat3(old_rotation, rotations[i]);
+    float3 old_axis;
+    mul_v3_m3v3(old_axis, old_rotation, main_axis);
+
+    const float3 new_axis = vector.normalized();
+    const float3 rotation_axis = float3::cross_high_precision(old_axis, new_axis);
+    const float full_angle = angle_normalized_v3v3(old_axis, new_axis);
+    const float angle = factors[i] * full_angle;
+
+    float rotation[3][3];
+    axis_angle_to_mat3(rotation, rotation_axis, angle);
+
+    float new_rotation_matrix[3][3];
+    mul_m3_m3m3(new_rotation_matrix, rotation, old_rotation);
+
+    float3 new_rotation;
+    mat3_to_eul(new_rotation, new_rotation_matrix);
+
+    rotations[i] = new_rotation;
+  }
+
+  rotation_attribute->apply_span();
+}
+
+static void geo_node_align_rotation_to_vector_exec(GeoNodeExecParams params)
+{
+  GeometrySet geometry_set = params.extract_input<GeometrySet>("Geometry");
+
+  if (geometry_set.has<MeshComponent>()) {
+    align_rotations_on_component(geometry_set.get_component_for_write<MeshComponent>(), params);
+  }
+  if (geometry_set.has<PointCloudComponent>()) {
+    align_rotations_on_component(geometry_set.get_component_for_write<PointCloudComponent>(),
+                                 params);
+  }
+
+  params.set_output("Geometry", geometry_set);
+}
+
+static void geo_node_align_rotation_to_vector_init(bNodeTree *UNUSED(ntree), bNode *node)
+{
+  NodeGeometryAlignRotationToVector *node_storage = (NodeGeometryAlignRotationToVector *)
+      MEM_callocN(sizeof(NodeGeometryAlignRotationToVector), __func__);
+
+  node_storage->axis = GEO_NODE_ALIGN_ROTATION_TO_VECTOR_AXIS_X;
+  node_storage->input_type_factor = GEO_NODE_ATTRIBUTE_INPUT_FLOAT;
+  node_storage->input_type_vector = GEO_NODE_ATTRIBUTE_INPUT_VECTOR;
+
+  node->storage = node_storage;
+}
+
+static void geo_node_align_rotation_to_vector_update(bNodeTree *UNUSED(ntree), bNode *node)
+{
+  NodeGeometryAlignRotationToVector *node_storage = (NodeGeometryAlignRotationToVector *)
+                                                        node->storage;
+  update_attribute_input_socket_availabilities(
+      *node, "Factor", (GeometryNodeAttributeInputMode)node_storage->input_type_factor);
+  update_attribute_input_socket_availabilities(
+      *node, "Vector", (GeometryNodeAttributeInputMode)node_storage->input_type_vector);
+}
+
+}  // namespace blender::nodes
+
+void register_node_type_geo_align_rotation_to_vector()
+{
+  static bNodeType ntype;
+
+  geo_node_type_base(&ntype,
+                     GEO_NODE_ALIGN_ROTATION_TO_VECTOR,
+                     "Align Rotation to Vector",
+                     NODE_CLASS_GEOMETRY,
+                     0);
+  node_type_socket_templates(
+      &ntype, geo_node_align_rotation_to_vector_in, geo_node_align_rotation_to_vector_out);
+  node_type_init(&ntype, blender::nodes::geo_node_align_rotation_to_vector_init);
+  node_type_update(&ntype, blender::nodes::geo_node_align_rotation_to_vector_update);
+  node_type_storage(&ntype,
+                    "NodeGeometryAlignRotationToVector",
+                    node_free_standard_storage,
+                    node_copy_standard_storage);
+  ntype.geometry_node_execute = blender::nodes::geo_node_align_rotation_to_vector_exec;
+  nodeRegisterType(&ntype);
+}