Curves: extract surface brush sampling into separate function

This functionality will also be necessary in the Density brush.

3 files changed, 106 insertions, 52 deletions

diff --git a/source/blender/editors/sculpt_paint/curves_sculpt_add.cc b/source/blender/editors/sculpt_paint/curves_sculpt_add.cc
index 7469c69e40b..bac03de77e7 100644
--- a/source/blender/editors/sculpt_paint/curves_sculpt_add.cc
+++ b/source/blender/editors/sculpt_paint/curves_sculpt_add.cc
@@ -334,73 +334,47 @@ struct AddOperationExecutor {
    */
   void sample_spherical_with_symmetry(RandomNumberGenerator &rng, AddedPoints &r_added_points)
   {
-    /* Find ray that starts in the center of the brush. */
-    float3 brush_ray_start_wo, brush_ray_end_wo;
-    ED_view3d_win_to_segment_clipped(ctx_.depsgraph,
-                                     ctx_.region,
-                                     ctx_.v3d,
-                                     brush_pos_re_,
-                                     brush_ray_start_wo,
-                                     brush_ray_end_wo,
-                                     true);
-    const float3 brush_ray_start_cu = transforms_.world_to_curves * brush_ray_start_wo;
-    const float3 brush_ray_end_cu = transforms_.world_to_curves * brush_ray_end_wo;
+    const std::optional<CurvesBrush3D> brush_3d = sample_curves_surface_3d_brush(*ctx_.depsgraph,
+                                                                                 *ctx_.region,
+                                                                                 *ctx_.v3d,
+                                                                                 transforms_,
+                                                                                 surface_bvh_,
+                                                                                 brush_pos_re_,
+                                                                                 brush_radius_re_);
+    if (!brush_3d.has_value()) {
+      return;
+    }
 
-    /* Find ray that starts on the boundary of the brush. That is used to compute the brush radius
-     * in 3D. */
-    float3 brush_radius_ray_start_wo, brush_radius_ray_end_wo;
+    float3 view_ray_start_wo, view_ray_end_wo;
     ED_view3d_win_to_segment_clipped(ctx_.depsgraph,
                                      ctx_.region,
                                      ctx_.v3d,
-                                     brush_pos_re_ + float2(brush_radius_re_, 0),
-                                     brush_radius_ray_start_wo,
-                                     brush_radius_ray_end_wo,
+                                     brush_pos_re_,
+                                     view_ray_start_wo,
+                                     view_ray_end_wo,
                                      true);
-    const float3 brush_radius_ray_start_cu = transforms_.world_to_curves *
-                                             brush_radius_ray_start_wo;
-    const float3 brush_radius_ray_end_cu = transforms_.world_to_curves * brush_radius_ray_end_wo;
+    const float3 view_direction_su = math::normalize(
+        transforms_.world_to_surface * view_ray_end_wo -
+        transforms_.world_to_surface * view_ray_start_wo);
 
     const Vector<float4x4> symmetry_brush_transforms = get_symmetry_brush_transforms(
         eCurvesSymmetryType(curves_id_->symmetry));
     for (const float4x4 &brush_transform : symmetry_brush_transforms) {
       const float4x4 transform = transforms_.curves_to_surface * brush_transform;
-      this->sample_spherical(rng,
-                             r_added_points,
-                             transform * brush_ray_start_cu,
-                             transform * brush_ray_end_cu,
-                             transform * brush_radius_ray_start_cu,
-                             transform * brush_radius_ray_end_cu);
+      const float3 brush_pos_su = transform * brush_3d->position_cu;
+      const float brush_radius_su = transform_brush_radius(
+          transform, brush_3d->position_cu, brush_3d->radius_cu);
+      this->sample_spherical(
+          rng, r_added_points, brush_pos_su, brush_radius_su, view_direction_su);
     }
   }
 
   void sample_spherical(RandomNumberGenerator &rng,
                         AddedPoints &r_added_points,
-                        const float3 &brush_ray_start_su,
-                        const float3 &brush_ray_end_su,
-                        const float3 &brush_radius_ray_start_su,
-                        const float3 &brush_radius_ray_end_su)
+                        const float3 &brush_pos_su,
+                        const float brush_radius_su,
+                        const float3 &view_direction_su)
   {
-    const float3 brush_ray_direction_su = math::normalize(brush_ray_end_su - brush_ray_start_su);
-
-    BVHTreeRayHit ray_hit;
-    ray_hit.dist = FLT_MAX;
-    ray_hit.index = -1;
-    BLI_bvhtree_ray_cast(surface_bvh_.tree,
-                         brush_ray_start_su,
-                         brush_ray_direction_su,
-                         0.0f,
-                         &ray_hit,
-                         surface_bvh_.raycast_callback,
-                         &surface_bvh_);
-
-    if (ray_hit.index == -1) {
-      return;
-    }
-
-    /* Compute brush radius. */
-    const float3 brush_pos_su = ray_hit.co;
-    const float brush_radius_su = dist_to_line_v3(
-        brush_pos_su, brush_radius_ray_start_su, brush_radius_ray_end_su);
     const float brush_radius_sq_su = pow2f(brush_radius_su);
 
     /* Find surface triangles within brush radius. */
@@ -417,7 +391,7 @@ struct AddOperationExecutor {
             const float3 v2_su = surface_->mvert[surface_->mloop[looptri.tri[2]].v].co;
             float3 normal_su;
             normal_tri_v3(normal_su, v0_su, v1_su, v2_su);
-            if (math::dot(normal_su, brush_ray_direction_su) >= 0.0f) {
+            if (math::dot(normal_su, view_direction_su) >= 0.0f) {
               return;
             }
             looptri_indices.append(index);
diff --git a/source/blender/editors/sculpt_paint/curves_sculpt_brush.cc b/source/blender/editors/sculpt_paint/curves_sculpt_brush.cc
index 5955c349eae..8c6ef34ef26 100644
--- a/source/blender/editors/sculpt_paint/curves_sculpt_brush.cc
+++ b/source/blender/editors/sculpt_paint/curves_sculpt_brush.cc
@@ -256,6 +256,55 @@ std::optional<CurvesBrush3D> sample_curves_3d_brush(const Depsgraph &depsgraph,
   return brush_3d;
 }
 
+std::optional<CurvesBrush3D> sample_curves_surface_3d_brush(
+    const Depsgraph &depsgraph,
+    const ARegion &region,
+    const View3D &v3d,
+    const CurvesSculptTransforms &transforms,
+    const BVHTreeFromMesh &surface_bvh,
+    const float2 &brush_pos_re,
+    const float brush_radius_re)
+{
+  float3 brush_ray_start_wo, brush_ray_end_wo;
+  ED_view3d_win_to_segment_clipped(
+      &depsgraph, &region, &v3d, brush_pos_re, brush_ray_start_wo, brush_ray_end_wo, true);
+  const float3 brush_ray_start_su = transforms.world_to_surface * brush_ray_start_wo;
+  const float3 brush_ray_end_su = transforms.world_to_surface * brush_ray_end_wo;
+
+  const float3 brush_ray_direction_su = math::normalize(brush_ray_end_su - brush_ray_start_su);
+
+  BVHTreeRayHit ray_hit;
+  ray_hit.dist = FLT_MAX;
+  ray_hit.index = -1;
+  BLI_bvhtree_ray_cast(surface_bvh.tree,
+                       brush_ray_start_su,
+                       brush_ray_direction_su,
+                       0.0f,
+                       &ray_hit,
+                       surface_bvh.raycast_callback,
+                       const_cast<void *>(static_cast<const void *>(&surface_bvh)));
+  if (ray_hit.index == -1) {
+    return std::nullopt;
+  }
+
+  float3 brush_radius_ray_start_wo, brush_radius_ray_end_wo;
+  ED_view3d_win_to_segment_clipped(&depsgraph,
+                                   &region,
+                                   &v3d,
+                                   brush_pos_re + float2(brush_radius_re, 0),
+                                   brush_radius_ray_start_wo,
+                                   brush_radius_ray_end_wo,
+                                   true);
+  const float3 brush_radius_ray_start_cu = transforms.world_to_curves * brush_radius_ray_start_wo;
+  const float3 brush_radius_ray_end_cu = transforms.world_to_curves * brush_radius_ray_end_wo;
+
+  const float3 brush_pos_su = ray_hit.co;
+  const float3 brush_pos_cu = transforms.surface_to_curves * brush_pos_su;
+  const float brush_radius_cu = dist_to_line_v3(
+      brush_pos_cu, brush_radius_ray_start_cu, brush_radius_ray_end_cu);
+  return CurvesBrush3D{brush_pos_cu, brush_radius_cu};
+}
+
 Vector<float4x4> get_symmetry_brush_transforms(const eCurvesSymmetryType symmetry)
 {
   Vector<float4x4> matrices;
@@ -284,6 +333,16 @@ Vector<float4x4> get_symmetry_brush_transforms(const eCurvesSymmetryType symmetr
   return matrices;
 }
 
+float transform_brush_radius(const float4x4 &transform,
+                             const float3 &brush_position,
+                             const float old_radius)
+{
+  const float3 offset_position = brush_position + float3(old_radius, 0.0f, 0.0f);
+  const float3 new_position = transform * brush_position;
+  const float3 new_offset_position = transform * offset_position;
+  return math::distance(new_position, new_offset_position);
+}
+
 void move_last_point_and_resample(MutableSpan<float3> positions, const float3 &new_last_position)
 {
   /* Find the accumulated length of each point in the original curve,
diff --git a/source/blender/editors/sculpt_paint/curves_sculpt_intern.hh b/source/blender/editors/sculpt_paint/curves_sculpt_intern.hh
index ce84d94fbd5..ad3871bee45 100644
--- a/source/blender/editors/sculpt_paint/curves_sculpt_intern.hh
+++ b/source/blender/editors/sculpt_paint/curves_sculpt_intern.hh
@@ -21,6 +21,7 @@ struct View3D;
 struct Object;
 struct Brush;
 struct Scene;
+struct BVHTreeFromMesh;
 
 namespace blender::ed::sculpt_paint {
 
@@ -60,6 +61,13 @@ std::unique_ptr<CurvesSculptStrokeOperation> new_grow_shrink_operation(
     const BrushStrokeMode brush_mode, const bContext &C);
 std::unique_ptr<CurvesSculptStrokeOperation> new_selection_paint_operation(
     const BrushStrokeMode brush_mode, const bContext &C);
+std::unique_ptr<CurvesSculptStrokeOperation> new_pinch_operation(const BrushStrokeMode brush_mode,
+                                                                 const bContext &C);
+std::unique_ptr<CurvesSculptStrokeOperation> new_smooth_operation();
+std::unique_ptr<CurvesSculptStrokeOperation> new_puff_operation();
+std::unique_ptr<CurvesSculptStrokeOperation> new_density_operation(
+    const BrushStrokeMode brush_mode, const bContext &C);
+std::unique_ptr<CurvesSculptStrokeOperation> new_slide_operation();
 
 struct CurvesBrush3D {
   float3 position_cu;
@@ -121,4 +129,17 @@ struct CurvesSculptTransforms {
   CurvesSculptTransforms(const Object &curves_ob, const Object *surface_ob);
 };
 
+std::optional<CurvesBrush3D> sample_curves_surface_3d_brush(
+    const Depsgraph &depsgraph,
+    const ARegion &region,
+    const View3D &v3d,
+    const CurvesSculptTransforms &transforms,
+    const BVHTreeFromMesh &surface_bvh,
+    const float2 &brush_pos_re,
+    const float brush_radius_re);
+
+float transform_brush_radius(const float4x4 &transform,
+                             const float3 &brush_position,
+                             const float old_radius);
+
 }  // namespace blender::ed::sculpt_paint