curves_sculpt_comb.cc

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/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#include "curves_sculpt_intern.hh"
 
#include "BLI_math_geom.h"
#include "BLI_math_matrix_types.hh"
#include "BLI_vector.hh"
 
#include "DEG_depsgraph.hh"
#include "DEG_depsgraph_query.hh"
 
#include "BKE_brush.hh"
#include "BKE_colortools.hh"
#include "BKE_context.hh"
#include "BKE_crazyspace.hh"
#include "BKE_curves.hh"
#include "BKE_geometry_set.hh"
#include "BKE_mesh.hh"
#include "BKE_mesh_runtime.hh"
#include "BKE_paint.hh"
 
#include "DNA_brush_enums.h"
#include "DNA_brush_types.h"
#include "DNA_curves_types.h"
#include "DNA_object_types.h"
#include "DNA_screen_types.h"
 
#include "ED_screen.hh"
#include "ED_view3d.hh"
 
#include "UI_interface.hh"
 
#include "WM_api.hh"
 
#include <numeric>

 
namespace blender::ed::sculpt_paint {
 
using blender::bke::CurvesGeometry;

class CombOperation : public CurvesSculptStrokeOperation {
 private:
  float2 brush_pos_last_re_;

  CurvesBrush3D brush_3d_;

  CurvesConstraintSolver constraint_solver_;
 
  Array<float> curve_lengths_;
 
  friend struct CombOperationExecutor;
 
 public:
  void on_stroke_extended(const bContext &C, const StrokeExtension &stroke_extension) override;
};

struct CombOperationExecutor {
  CombOperation *self_ = nullptr;
  CurvesSculptCommonContext ctx_;
 
  const CurvesSculpt *curves_sculpt_ = nullptr;
  const Brush *brush_ = nullptr;
  float brush_radius_base_re_;
  float brush_radius_factor_;
  float brush_strength_;
 
  Object *curves_ob_orig_ = nullptr;
  Curves *curves_id_orig_ = nullptr;
  CurvesGeometry *curves_orig_ = nullptr;
 
  VArray<float> point_factors_;
  IndexMaskMemory selected_curve_memory_;
  IndexMask curve_selection_;
 
  float2 brush_pos_prev_re_;
  float2 brush_pos_re_;
  float2 brush_pos_diff_re_;
 
  CurvesSurfaceTransforms transforms_;
 
  CombOperationExecutor(const bContext &C) : ctx_(C) {}
 
  void execute(CombOperation &self, const bContext &C, const StrokeExtension &stroke_extension)
  {
    self_ = &self;
 
    BLI_SCOPED_DEFER([&]() { self_->brush_pos_last_re_ = stroke_extension.mouse_position; });
 
    curves_ob_orig_ = CTX_data_active_object(&C);
    curves_id_orig_ = static_cast<Curves *>(curves_ob_orig_->data);
    curves_orig_ = &curves_id_orig_->geometry.wrap();
    if (curves_orig_->is_empty()) {
      return;
    }
 
    curves_sculpt_ = ctx_.scene->toolsettings->curves_sculpt;
    brush_ = BKE_paint_brush_for_read(&curves_sculpt_->paint);
    brush_radius_base_re_ = BKE_brush_size_get(ctx_.scene, brush_);
    brush_radius_factor_ = brush_radius_factor(*brush_, stroke_extension);
    brush_strength_ = brush_strength_get(*ctx_.scene, *brush_, stroke_extension);
 
    const eBrushFalloffShape falloff_shape = eBrushFalloffShape(brush_->falloff_shape);
 
    transforms_ = CurvesSurfaceTransforms(*curves_ob_orig_, curves_id_orig_->surface);
 
    point_factors_ = *curves_orig_->attributes().lookup_or_default<float>(
        ".selection", bke::AttrDomain::Point, 1.0f);
    curve_selection_ = curves::retrieve_selected_curves(*curves_id_orig_, selected_curve_memory_);
 
    brush_pos_prev_re_ = self_->brush_pos_last_re_;
    brush_pos_re_ = stroke_extension.mouse_position;
    brush_pos_diff_re_ = brush_pos_re_ - brush_pos_prev_re_;
 
    if (stroke_extension.is_first) {
      if (falloff_shape == PAINT_FALLOFF_SHAPE_SPHERE || (U.uiflag & USER_ORBIT_SELECTION)) {
        this->initialize_spherical_brush_reference_point();
      }
      self_->constraint_solver_.initialize(*curves_orig_,
                                           curve_selection_,
                                           curves_id_orig_->flag & CV_SCULPT_COLLISION_ENABLED,
                                           curves_id_orig_->surface_collision_distance);
 
      self_->curve_lengths_.reinitialize(curves_orig_->curves_num());
      const Span<float> segment_lengths = self_->constraint_solver_.segment_lengths();
      const OffsetIndices points_by_curve = curves_orig_->points_by_curve();
      curve_selection_.foreach_segment(GrainSize(512), [&](const IndexMaskSegment segment) {
        for (const int curve_i : segment) {
          const IndexRange points = points_by_curve[curve_i];
          const Span<float> lengths = segment_lengths.slice(points.drop_back(1));
          self_->curve_lengths_[curve_i] = std::accumulate(lengths.begin(), lengths.end(), 0.0f);
        }
      });
      /* Combing does nothing when there is no mouse movement, so return directly. */
      return;
    }
 
    Array<bool> changed_curves(curves_orig_->curves_num(), false);
 
    if (falloff_shape == PAINT_FALLOFF_SHAPE_TUBE) {
      this->comb_projected_with_symmetry(changed_curves);
    }
    else if (falloff_shape == PAINT_FALLOFF_SHAPE_SPHERE) {
      this->comb_spherical_with_symmetry(changed_curves);
    }
    else {
      BLI_assert_unreachable();
    }
 
    const Mesh *surface = curves_id_orig_->surface && curves_id_orig_->surface->type == OB_MESH ?
                              static_cast<Mesh *>(curves_id_orig_->surface->data) :
                              nullptr;
 
    IndexMaskMemory memory;
    const IndexMask changed_curves_mask = IndexMask::from_bools(changed_curves, memory);
    self_->constraint_solver_.solve_step(*curves_orig_, changed_curves_mask, surface, transforms_);
 
    curves_orig_->tag_positions_changed();
    DEG_id_tag_update(&curves_id_orig_->id, ID_RECALC_GEOMETRY);
    WM_main_add_notifier(NC_GEOM | ND_DATA, &curves_id_orig_->id);
    ED_region_tag_redraw(ctx_.region);
  }

  void comb_projected_with_symmetry(MutableSpan<bool> r_changed_curves)
  {
    const Vector<float4x4> symmetry_brush_transforms = get_symmetry_brush_transforms(
        eCurvesSymmetryType(curves_id_orig_->symmetry));
    for (const float4x4 &brush_transform : symmetry_brush_transforms) {
      this->comb_projected(r_changed_curves, brush_transform);
    }
  }
 
  void comb_projected(MutableSpan<bool> r_changed_curves, const float4x4 &brush_transform)
  {
    const float4x4 brush_transform_inv = math::invert(brush_transform);
 
    MutableSpan<float3> positions_cu_orig = curves_orig_->positions_for_write();
    const bke::crazyspace::GeometryDeformation deformation =
        bke::crazyspace::get_evaluated_curves_deformation(*ctx_.depsgraph, *curves_ob_orig_);
    const OffsetIndices points_by_curve = curves_orig_->points_by_curve();
 
    const float4x4 projection = ED_view3d_ob_project_mat_get(ctx_.rv3d, curves_ob_orig_);
 
    const float brush_radius_re = brush_radius_base_re_ * brush_radius_factor_;
    const float brush_radius_sq_re = pow2f(brush_radius_re);
 
    CurveMapping &curve_parameter_falloff_mapping =
        *brush_->curves_sculpt_settings->curve_parameter_falloff;
    BKE_curvemapping_init(&curve_parameter_falloff_mapping);
 
    const Span<float> segment_lengths = self_->constraint_solver_.segment_lengths();
 
    curve_selection_.foreach_segment(GrainSize(256), [&](const IndexMaskSegment segment) {
      for (const int curve_i : segment) {
        bool curve_changed = false;
        const IndexRange points = points_by_curve[curve_i];
 
        const float total_length = self_->curve_lengths_[curve_i];
        const float total_length_inv = math::safe_rcp(total_length);
        float current_length = 0.0f;
        for (const int point_i : points.drop_front(1)) {
          current_length += segment_lengths[point_i - 1];
 
          const float3 old_pos_cu = deformation.positions[point_i];
          const float3 old_symm_pos_cu = math::transform_point(brush_transform_inv, old_pos_cu);
 
          /* Find the position of the point in screen space. */
          const float2 old_symm_pos_re = ED_view3d_project_float_v2_m4(
              ctx_.region, old_symm_pos_cu, projection);
 
          const float distance_to_brush_sq_re = dist_squared_to_line_segment_v2(
              old_symm_pos_re, brush_pos_prev_re_, brush_pos_re_);
          if (distance_to_brush_sq_re > brush_radius_sq_re) {
            /* Ignore the point because it's too far away. */
            continue;
          }
 
          const float distance_to_brush_re = std::sqrt(distance_to_brush_sq_re);
          /* A falloff that is based on how far away the point is from the stroke. */
          const float radius_falloff = BKE_brush_curve_strength(
              brush_, distance_to_brush_re, brush_radius_re);
          const float curve_parameter = current_length * total_length_inv;
          const float curve_falloff = BKE_curvemapping_evaluateF(
              &curve_parameter_falloff_mapping, 0, curve_parameter);
          /* Combine the falloff and brush strength. */
          const float weight = brush_strength_ * curve_falloff * radius_falloff *
                               point_factors_[point_i];
 
          /* Offset the old point position in screen space and transform it back into 3D space.
           */
          const float2 new_symm_pos_re = old_symm_pos_re + brush_pos_diff_re_ * weight;
          float3 new_symm_pos_wo;
          ED_view3d_win_to_3d(ctx_.v3d,
                              ctx_.region,
                              math::transform_point(transforms_.curves_to_world, old_symm_pos_cu),
                              new_symm_pos_re,
                              new_symm_pos_wo);
          const float3 new_pos_cu = math::transform_point(
              brush_transform,
              math::transform_point(transforms_.world_to_curves, new_symm_pos_wo));
 
          const float3 translation_eval = new_pos_cu - old_pos_cu;
          const float3 translation_orig = deformation.translation_from_deformed_to_original(
              point_i, translation_eval);
          positions_cu_orig[point_i] += translation_orig;
 
          curve_changed = true;
        }
        if (curve_changed) {
          r_changed_curves[curve_i] = true;
        }
      }
    });
  }

  void comb_spherical_with_symmetry(MutableSpan<bool> r_changed_curves)
  {
    float3 brush_start_wo, brush_end_wo;
    ED_view3d_win_to_3d(
        ctx_.v3d,
        ctx_.region,
        math::transform_point(transforms_.curves_to_world, self_->brush_3d_.position_cu),
        brush_pos_prev_re_,
        brush_start_wo);
    ED_view3d_win_to_3d(
        ctx_.v3d,
        ctx_.region,
        math::transform_point(transforms_.curves_to_world, self_->brush_3d_.position_cu),
        brush_pos_re_,
        brush_end_wo);
    const float3 brush_start_cu = math::transform_point(transforms_.world_to_curves,
                                                        brush_start_wo);
    const float3 brush_end_cu = math::transform_point(transforms_.world_to_curves, brush_end_wo);
 
    const float brush_radius_cu = self_->brush_3d_.radius_cu * brush_radius_factor_;
 
    const Vector<float4x4> symmetry_brush_transforms = get_symmetry_brush_transforms(
        eCurvesSymmetryType(curves_id_orig_->symmetry));
    for (const float4x4 &brush_transform : symmetry_brush_transforms) {
      this->comb_spherical(r_changed_curves,
                           math::transform_point(brush_transform, brush_start_cu),
                           math::transform_point(brush_transform, brush_end_cu),
                           brush_radius_cu);
    }
  }
 
  void comb_spherical(MutableSpan<bool> r_changed_curves,
                      const float3 &brush_start_cu,
                      const float3 &brush_end_cu,
                      const float brush_radius_cu)
  {
    MutableSpan<float3> positions_cu = curves_orig_->positions_for_write();
    const float brush_radius_sq_cu = pow2f(brush_radius_cu);
    const float3 brush_diff_cu = brush_end_cu - brush_start_cu;
 
    CurveMapping &curve_parameter_falloff_mapping =
        *brush_->curves_sculpt_settings->curve_parameter_falloff;
    BKE_curvemapping_init(&curve_parameter_falloff_mapping);
 
    const bke::crazyspace::GeometryDeformation deformation =
        bke::crazyspace::get_evaluated_curves_deformation(*ctx_.depsgraph, *curves_ob_orig_);
    const OffsetIndices points_by_curve = curves_orig_->points_by_curve();
    const Span<float> segment_lengths = self_->constraint_solver_.segment_lengths();
 
    curve_selection_.foreach_segment(GrainSize(256), [&](const IndexMaskSegment segment) {
      for (const int curve_i : segment) {
        bool curve_changed = false;
        const IndexRange points = points_by_curve[curve_i];
 
        const float total_length = self_->curve_lengths_[curve_i];
        const float total_length_inv = math::safe_rcp(total_length);
        float current_length = 0.0f;
        for (const int point_i : points.drop_front(1)) {
          current_length += segment_lengths[point_i - 1];
 
          const float3 pos_old_cu = deformation.positions[point_i];
 
          /* Compute distance to the brush. */
          const float distance_to_brush_sq_cu = dist_squared_to_line_segment_v3(
              pos_old_cu, brush_start_cu, brush_end_cu);
          if (distance_to_brush_sq_cu > brush_radius_sq_cu) {
            /* Ignore the point because it's too far away. */
            continue;
          }
 
          const float distance_to_brush_cu = std::sqrt(distance_to_brush_sq_cu);
 
          /* A falloff that is based on how far away the point is from the stroke. */
          const float radius_falloff = BKE_brush_curve_strength(
              brush_, distance_to_brush_cu, brush_radius_cu);
          const float curve_parameter = current_length * total_length_inv;
          const float curve_falloff = BKE_curvemapping_evaluateF(
              &curve_parameter_falloff_mapping, 0, curve_parameter);
          /* Combine the falloff and brush strength. */
          const float weight = brush_strength_ * curve_falloff * radius_falloff *
                               point_factors_[point_i];
 
          const float3 translation_eval_cu = weight * brush_diff_cu;
          const float3 translation_orig_cu = deformation.translation_from_deformed_to_original(
              point_i, translation_eval_cu);
 
          /* Update the point position. */
          positions_cu[point_i] += translation_orig_cu;
          curve_changed = true;
        }
        if (curve_changed) {
          r_changed_curves[curve_i] = true;
        }
      }
    });
  }

  void initialize_spherical_brush_reference_point()
  {
    std::optional<CurvesBrush3D> brush_3d = sample_curves_3d_brush(*ctx_.depsgraph,
                                                                   *ctx_.region,
                                                                   *ctx_.v3d,
                                                                   *ctx_.rv3d,
                                                                   *curves_ob_orig_,
                                                                   brush_pos_re_,
                                                                   brush_radius_base_re_);
    if (brush_3d.has_value()) {
      self_->brush_3d_ = *brush_3d;
      remember_stroke_position(
          *ctx_.scene,
          math::transform_point(transforms_.curves_to_world, self_->brush_3d_.position_cu));
    }
  }
};
 
void CombOperation::on_stroke_extended(const bContext &C, const StrokeExtension &stroke_extension)
{
  CombOperationExecutor executor{C};
  executor.execute(*this, C, stroke_extension);
}
 
std::unique_ptr<CurvesSculptStrokeOperation> new_comb_operation()
{
  return std::make_unique<CombOperation>();
}
 
}  // namespace blender::ed::sculpt_paint