Cleanup: Use const in curves sculpt code

This makes it much clearer what data is supposed to be modified
and what data is just used to influence the operation. The new
`BKE_paint_brush_for_read` function isn't great design, but it
can be removed or renamed if similar changes are applied to
more places.

Also pass pointers explicitly to `sample_curves_3d_brush` rather
than reusing the `bContext`. This makes it clearer what data the
function actually needs.

Differential Revision: https://developer.blender.org/D14967

1 files changed, 12 insertions, 6 deletions

diff --git a/source/blender/editors/sculpt_paint/curves_sculpt_intern.hh b/source/blender/editors/sculpt_paint/curves_sculpt_intern.hh
index 9d000649d62..00e7213b5e6 100644
--- a/source/blender/editors/sculpt_paint/curves_sculpt_intern.hh
+++ b/source/blender/editors/sculpt_paint/curves_sculpt_intern.hh
@@ -13,6 +13,8 @@
 
 struct ARegion;
 struct RegionView3D;
+struct Depsgraph;
+struct View3D;
 struct Object;
 
 namespace blender::ed::sculpt_paint {
@@ -30,15 +32,16 @@ struct StrokeExtension {
 class CurvesSculptStrokeOperation {
  public:
   virtual ~CurvesSculptStrokeOperation() = default;
-  virtual void on_stroke_extended(bContext *C, const StrokeExtension &stroke_extension) = 0;
+  virtual void on_stroke_extended(const bContext &C, const StrokeExtension &stroke_extension) = 0;
 };
 
-std::unique_ptr<CurvesSculptStrokeOperation> new_add_operation(bContext &C, ReportList *reports);
+std::unique_ptr<CurvesSculptStrokeOperation> new_add_operation(const bContext &C,
+                                                               ReportList *reports);
 std::unique_ptr<CurvesSculptStrokeOperation> new_comb_operation();
 std::unique_ptr<CurvesSculptStrokeOperation> new_delete_operation();
 std::unique_ptr<CurvesSculptStrokeOperation> new_snake_hook_operation();
 std::unique_ptr<CurvesSculptStrokeOperation> new_grow_shrink_operation(
-    const BrushStrokeMode brush_mode, bContext *C);
+    const BrushStrokeMode brush_mode, const bContext &C);
 
 struct CurvesBrush3D {
   float3 position_cu;
@@ -48,10 +51,13 @@ struct CurvesBrush3D {
 /**
  * Find 3d brush position based on cursor position for curves sculpting.
  */
-std::optional<CurvesBrush3D> sample_curves_3d_brush(bContext &C,
-                                                    Object &curves_object,
+std::optional<CurvesBrush3D> sample_curves_3d_brush(const Depsgraph &depsgraph,
+                                                    const ARegion &region,
+                                                    const View3D &v3d,
+                                                    const RegionView3D &rv3d,
+                                                    const Object &curves_object,
                                                     const float2 &brush_pos_re,
-                                                    float brush_radius_re);
+                                                    const float brush_radius_re);
 
 Vector<float4x4> get_symmetry_brush_transforms(eCurvesSymmetryType symmetry);