Geometry Nodes: Add Offset Option to Set Postion

Add a boolean field to the Set Position Node. This value allows
for each point to either have its position set to the input position
value or have the input value added to the current position.

Differential Revision: https://developer.blender.org/D12773

1 files changed, 21 insertions, 4 deletions

diff --git a/source/blender/nodes/geometry/nodes/node_geo_set_position.cc b/source/blender/nodes/geometry/nodes/node_geo_set_position.cc
index 8caf961fc04..15930508e78 100644
--- a/source/blender/nodes/geometry/nodes/node_geo_set_position.cc
+++ b/source/blender/nodes/geometry/nodes/node_geo_set_position.cc
@@ -23,14 +23,16 @@ namespace blender::nodes {
 static void geo_node_set_position_declare(NodeDeclarationBuilder &b)
 {
   b.add_input<decl::Geometry>("Geometry");
-  b.add_input<decl::Vector>("Position").implicit_field();
   b.add_input<decl::Bool>("Selection").default_value(true).hide_value().supports_field();
+  b.add_input<decl::Vector>("Position").implicit_field();
+  b.add_input<decl::Bool>("Offset").default_value(false).supports_field();
   b.add_output<decl::Geometry>("Geometry");
 }
 
 static void set_position_in_component(GeometryComponent &component,
                                       const Field<bool> &selection_field,
-                                      const Field<float3> &position_field)
+                                      const Field<float3> &position_field,
+                                      const Field<bool> &offset_field)
 {
   GeometryComponentFieldContext field_context{component, ATTR_DOMAIN_POINT};
   const int domain_size = component.attribute_domain_size(ATTR_DOMAIN_POINT);
@@ -45,9 +47,23 @@ static void set_position_in_component(GeometryComponent &component,
 
   OutputAttribute_Typed<float3> positions = component.attribute_try_get_for_output<float3>(
       "position", ATTR_DOMAIN_POINT, {0, 0, 0});
+  MutableSpan<float3> position_mutable = positions.as_span();
+
   fn::FieldEvaluator position_evaluator{field_context, &selection};
-  position_evaluator.add_with_destination(position_field, positions.varray());
+  position_evaluator.add(position_field);
+  position_evaluator.add(offset_field);
   position_evaluator.evaluate();
+
+  /* TODO: We could have different code paths depending on whether the offset input is a single
+   * value or not */
+
+  const VArray<float3> &positions_input = position_evaluator.get_evaluated<float3>(0);
+  const VArray<bool> &offsets_input = position_evaluator.get_evaluated<bool>(1);
+
+  for (int i : selection) {
+    position_mutable[i] = offsets_input[i] ? position_mutable[i] + positions_input[i] :
+                                             positions_input[i];
+  }
   positions.save();
 }
 
@@ -55,6 +71,7 @@ static void geo_node_set_position_exec(GeoNodeExecParams params)
 {
   GeometrySet geometry = params.extract_input<GeometrySet>("Geometry");
   Field<bool> selection_field = params.extract_input<Field<bool>>("Selection");
+  Field<bool> offset_field = params.extract_input<Field<bool>>("Offset");
   Field<float3> position_field = params.extract_input<Field<float3>>("Position");
 
   for (const GeometryComponentType type : {GEO_COMPONENT_TYPE_MESH,
@@ -63,7 +80,7 @@ static void geo_node_set_position_exec(GeoNodeExecParams params)
                                            GEO_COMPONENT_TYPE_INSTANCES}) {
     if (geometry.has(type)) {
       set_position_in_component(
-          geometry.get_component_for_write(type), selection_field, position_field);
+          geometry.get_component_for_write(type), selection_field, position_field, offset_field);
     }
   }