grease_pencil_sculpt_randomize.cc

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/* SPDX-FileCopyrightText: 2024 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#include "BLI_hash.h"
#include "BLI_math_vector.hh"
#include "BLI_rand.hh"
#include "BLI_task.hh"
 
#include "DNA_brush_types.h"
 
#include "BKE_context.hh"
#include "BKE_crazyspace.hh"
#include "BKE_curves.hh"
#include "BKE_grease_pencil.hh"
#include "BKE_paint.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 {
 
/* Use a hash to generate random numbers. */
static float hash_rng(uint32_t seed1, uint32_t seed2, int index)
{
  return BLI_hash_int_01(BLI_hash_int_3d(seed1, seed2, uint32_t(index)));
}
 
class RandomizeOperation : public GreasePencilStrokeOperationCommon {
 public:
  using GreasePencilStrokeOperationCommon::GreasePencilStrokeOperationCommon;
 
  /* Get a different seed value for each stroke. */
  uint32_t unique_seed() const;
 
  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 {}
};
 
uint32_t RandomizeOperation::unique_seed() const
{
  return RandomNumberGenerator::from_random_seed().get_uint32();
}
 
void RandomizeOperation::on_stroke_begin(const bContext &C, const InputSample &start_sample)
{
  this->init_stroke(C, start_sample);
  this->init_auto_masking(C, start_sample);
}
 
void RandomizeOperation::on_stroke_extended(const bContext &C, const InputSample &extension_sample)
{
  Paint &paint = *BKE_paint_get_active_from_context(&C);
  const Brush &brush = *BKE_paint_brush(&paint);
  const int sculpt_mode_flag = brush.gpencil_settings->sculpt_mode_flag;
 
  this->foreach_editable_drawing_with_automask(
      C,
      [&](const GreasePencilStrokeParams &params,
          const IndexMask &point_mask,
          const DeltaProjectionFunc &projection_fn) {
        const uint32_t seed = this->unique_seed();
 
        bke::crazyspace::GeometryDeformation deformation = get_drawing_deformation(params);
        Array<float2> view_positions = calculate_view_positions(params, point_mask);
        bke::CurvesGeometry &curves = params.drawing.strokes_for_write();
        bke::MutableAttributeAccessor attributes = curves.attributes_for_write();
 
        bool changed = false;
        if (sculpt_mode_flag & GP_SCULPT_FLAGMODE_APPLY_POSITION) {
          MutableSpan<float3> positions = curves.positions_for_write();
 
          /* Jitter is applied perpendicular to the mouse movement vector. */
          const float2 forward = math::normalize(this->mouse_delta(extension_sample));
          const float2 sideways = float2(-forward.y, forward.x);
 
          point_mask.foreach_index(GrainSize(4096), [&](const int64_t point_i) {
            const float2 &co = view_positions[point_i];
            const float influence = brush_point_influence(
                paint, brush, co, extension_sample, params.multi_frame_falloff);
            if (influence <= 0.0f) {
              return;
            }
            const float noise = 2.0f * hash_rng(seed, 5678, point_i) - 1.0f;
            positions[point_i] += compute_orig_delta(
                projection_fn, deformation, point_i, sideways * influence * noise);
          });
 
          params.drawing.tag_positions_changed();
          changed = true;
        }
        if (sculpt_mode_flag & GP_SCULPT_FLAGMODE_APPLY_STRENGTH) {
          MutableSpan<float> opacities = params.drawing.opacities_for_write();
          point_mask.foreach_index(GrainSize(4096), [&](const int64_t point_i) {
            const float2 &co = view_positions[point_i];
            const float influence = brush_point_influence(
                paint, brush, co, extension_sample, params.multi_frame_falloff);
            if (influence <= 0.0f) {
              return;
            }
            const float noise = 2.0f * hash_rng(seed, 1212, point_i) - 1.0f;
            opacities[point_i] = math::clamp(opacities[point_i] + influence * noise, 0.0f, 1.0f);
          });
          changed = true;
        }
        if (sculpt_mode_flag & GP_SCULPT_FLAGMODE_APPLY_THICKNESS) {
          const MutableSpan<float> radii = params.drawing.radii_for_write();
          point_mask.foreach_index(GrainSize(4096), [&](const int64_t point_i) {
            const float2 &co = view_positions[point_i];
            const float influence = brush_point_influence(
                paint, brush, co, extension_sample, params.multi_frame_falloff);
            if (influence <= 0.0f) {
              return;
            }
            const float noise = 2.0f * hash_rng(seed, 1212, point_i) - 1.0f;
            radii[point_i] = math::max(radii[point_i] + influence * noise * 0.001f, 0.0f);
          });
          curves.tag_radii_changed();
          changed = true;
        }
        if (sculpt_mode_flag & GP_SCULPT_FLAGMODE_APPLY_UV) {
          if (bke::SpanAttributeWriter<float> rotations =
                  attributes.lookup_or_add_for_write_span<float>("rotation",
                                                                 bke::AttrDomain::Point))
          {
            point_mask.foreach_index(GrainSize(4096), [&](const int64_t point_i) {
              const float2 &co = view_positions[point_i];
              const float influence = brush_point_influence(
                  paint, brush, co, extension_sample, params.multi_frame_falloff);
              if (influence <= 0.0f) {
                return;
              }
              const float noise = 2.0f * hash_rng(seed, 1212, point_i) - 1.0f;
              rotations.span[point_i] = math::clamp(
                  rotations.span[point_i] + influence * noise, -float(M_PI_2), float(M_PI_2));
            });
            rotations.finish();
            changed = true;
          }
        }
        return changed;
      });
  this->stroke_extended(extension_sample);
}
 
std::unique_ptr<GreasePencilStrokeOperation> new_randomize_operation(
    const BrushStrokeMode stroke_mode)
{
  return std::make_unique<RandomizeOperation>(stroke_mode);
}
 
}  // namespace blender::ed::sculpt_paint::greasepencil