grease_pencil_sculpt_clone.cc

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/* SPDX-FileCopyrightText: 2024 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#include "BKE_context.hh"
#include "BKE_curves.hh"
#include "BKE_grease_pencil.hh"
#include "BKE_paint.hh"
 
#include "ED_curves.hh"
#include "ED_grease_pencil.hh"
#include "ED_view3d.hh"
 
#include "WM_api.hh"
#include "WM_types.hh"
 
#include "grease_pencil_intern.hh"
#include "paint_intern.hh"
 
namespace blender::ed::sculpt_paint::greasepencil {
 
class CloneOperation : public GreasePencilStrokeOperationCommon {
 public:
  using GreasePencilStrokeOperationCommon::GreasePencilStrokeOperationCommon;
 
  void on_stroke_begin(const bContext &C, const InputSample &start_sample) override;
  void on_stroke_extended(const bContext &C, const InputSample &extension_sample) override;
  void on_stroke_done(const bContext & /*C*/) override {}
};
 
static float2 arithmetic_mean(Span<float2> values)
{
  return std::accumulate(values.begin(), values.end(), float2(0)) / values.size();
}
 
void CloneOperation::on_stroke_begin(const bContext &C, const InputSample &start_sample)
{
  Main &bmain = *CTX_data_main(&C);
  Object &object = *CTX_data_active_object(&C);
  GreasePencil &grease_pencil = *static_cast<GreasePencil *>(object.data);
 
  this->init_stroke(C, start_sample);
 
  /* NOTE: Only one copy is created at the beginning of each stroke.
   * GPv2 supposedly has 2 modes:
   * - Stamp: Clone on stroke start and then transform (the transform part doesn't work)
   * - Continuous: Create multiple copies during the stroke (disabled)
   *
   * Here we only have the GPv2 behavior that actually works for now. */
  this->foreach_editable_drawing(
      C, [&](const GreasePencilStrokeParams &params, const DeltaProjectionFunc &projection_fn) {
        /* Only insert on the active layer. */
        if (&params.layer != grease_pencil.get_active_layer()) {
          return false;
        }
 
        /* TODO Could become a tool setting. */
        const bool keep_world_transform = false;
        const float4x4 clipboard_to_layer = math::invert(params.layer.to_world_space(object));
        const IndexRange pasted_curves = ed::greasepencil::clipboard_paste_strokes(
            bmain, object, params.drawing, clipboard_to_layer, keep_world_transform, false);
        if (pasted_curves.is_empty()) {
          return false;
        }
 
        const bke::crazyspace::GeometryDeformation deformation = get_drawing_deformation(params);
        bke::CurvesGeometry &curves = params.drawing.strokes_for_write();
        const OffsetIndices<int> pasted_points_by_curve = curves.points_by_curve().slice(
            pasted_curves);
        const IndexRange pasted_points = IndexRange::from_begin_size(
            pasted_points_by_curve[0].start(), pasted_points_by_curve.total_size());
        if (pasted_points.is_empty()) {
          return false;
        }
 
        Array<float2> view_positions = calculate_view_positions(params, pasted_points);
        const float2 center = arithmetic_mean(
            view_positions.as_mutable_span().slice(pasted_points));
        const float2 &mouse_delta = start_sample.mouse_position - center;
 
        MutableSpan<float3> positions = curves.positions_for_write();
        threading::parallel_for(pasted_points, 4096, [&](const IndexRange range) {
          for (const int point_i : range) {
            positions[point_i] = projection_fn(deformation.positions[point_i], mouse_delta);
          }
        });
        params.drawing.tag_positions_changed();
 
        return true;
      });
}
 
void CloneOperation::on_stroke_extended(const bContext & /*C*/,
                                        const InputSample &extension_sample)
{
  this->stroke_extended(extension_sample);
}
 
std::unique_ptr<GreasePencilStrokeOperation> new_clone_operation(const BrushStrokeMode stroke_mode)
{
  return std::make_unique<CloneOperation>(stroke_mode);
}
 
}  // namespace blender::ed::sculpt_paint::greasepencil