# Grease Pencil / Geometry Nodes

Known Issues:
* Need to propagate attributes from layer:
* node_geo_instance_on_points.cc
* node_geo_curve_to_points.cc
* Radius has a scaled up factor
* node_geo_instance_on_points.cc
* node_geo_curve_to_points.cc

## Code Snipets

/** Use multi-function to pipe fields. */
static void grease_pencil_radius_to_blender_unit(PointCloud &pointcloud)
{
  MutableAttributeAccessor attributes = pointcloud.attributes_for_write();
  AttributeWriter<float> radii = attributes.lookup_or_add_for_write<float>("radius",
                                                                           ATTR_DOMAIN_POINT);
  Field<float> radius_field = AttributeFieldInput::Create<float>("radius");

  static auto fn = mf::build::SI1_SO<float, float>(
      "Grease Pencil Radius",
      [](float a) { return a / 2000.0f; },
      mf::build::exec_presets::AllSpanOrSingle());

  const bke::PointCloudFieldContext field_context{pointcloud};
  fn::FieldEvaluator evaluator{field_context, pointcloud.totpoint};

  fn::Field<float> grease_pencil_scale_field(fn::FieldOperation::Create(fn, {radius_field}));
  evaluator.add_with_destination(grease_pencil_scale_field, radii.varray);
  evaluator.evaluate();
  radii.finish();
}

/** Using span and parallel loop for simpler code. */
static void grease_pencil_radius_to_blender_unit(PointCloud &pointcloud)
      bke::SpanAttributeWriter<float> point_radii =
      attributes.lookup_or_add_for_write_only_span<float>("radius", ATTR_DOMAIN_POINT);

  threading::parallel_for(point_radii.span.index_range(), 1024, [&](const IndexRange range) {
    for (const int i : range) {
      point_radii.span[i] /= 2000.0;
    }
  });

  point_radii.finish();
}

fn::make_constant_field<bool>(true);

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