From b2cff223a1403b64a79b5ec4c9819096d7abaebe Mon Sep 17 00:00:00 2001
From: Casey Bianco-Davis <caseycasey739@gmail.com>
Date: Wed, 16 Oct 2024 11:17:26 +0200
Subject: [PATCH] Fix: #126515: Brush radius sensitivity not consisted at
 different zoom levels

The problem was that the screen space size of the brush was not updated.
This was not fully noticeable because the radius control operator was using
a not working scale correction.
The solution remove the scale correction and just update the brush size.

Note: This update currently happens when the cursor is drawn.

Pull Request: https://projects.blender.org/blender/blender/pulls/126773
---
 .../editors/sculpt_paint/paint_cursor.cc      |  1 +
 .../windowmanager/intern/wm_operators.cc      | 41 -------------------
 2 files changed, 1 insertion(+), 41 deletions(-)

diff --git a/source/blender/editors/sculpt_paint/paint_cursor.cc b/source/blender/editors/sculpt_paint/paint_cursor.cc
index 9db79b9aca0..94c92f3a2a7 100644
--- a/source/blender/editors/sculpt_paint/paint_cursor.cc
+++ b/source/blender/editors/sculpt_paint/paint_cursor.cc
@@ -1567,6 +1567,7 @@ static void grease_pencil_brush_cursor_draw(PaintCursorContext *pcontext)
         const float3 location = placement.project(float2(pcontext->x, pcontext->y));
         pcontext->pixel_radius = project_brush_radius(
             &pcontext->vc, brush->unprojected_radius, location);
+        brush->size = pcontext->pixel_radius;
       }
       else {
         pcontext->pixel_radius = brush->size;
diff --git a/source/blender/windowmanager/intern/wm_operators.cc b/source/blender/windowmanager/intern/wm_operators.cc
index 6a8da90cda0..b1b7387cc41 100644
--- a/source/blender/windowmanager/intern/wm_operators.cc
+++ b/source/blender/windowmanager/intern/wm_operators.cc
@@ -2525,7 +2525,6 @@ struct RadialControl {
   int initial_co[2];
   int slow_mouse[2];
   bool slow_mode;
-  float scale_fac;
   Dial *dial;
   GPUTexture *texture;
   ListBase orig_paintcursors;
@@ -2575,31 +2574,6 @@ static void radial_control_update_header(wmOperator *op, bContext *C)
   ED_area_status_text(area, msg);
 }
 
-/* Helper: Compute the brush radius in pixels at the mouse position. */
-static float grease_pencil_unprojected_brush_radius_pixel_size(const bContext *C,
-                                                               const Brush *brush,
-                                                               const blender::float2 mval)
-{
-  using namespace blender;
-  Scene *scene = CTX_data_scene(C);
-  ARegion *region = CTX_wm_region(C);
-  View3D *view3d = CTX_wm_view3d(C);
-  RegionView3D *rv3d = CTX_wm_region_view3d(C);
-  Object *object = CTX_data_active_object(C);
-  Depsgraph *depsgraph = CTX_data_depsgraph_pointer(C);
-  Object *eval_object = DEG_get_evaluated_object(depsgraph, object);
-
-  BLI_assert(object->type == OB_GREASE_PENCIL);
-  GreasePencil *grease_pencil = static_cast<GreasePencil *>(eval_object->data);
-
-  ed::greasepencil::DrawingPlacement placement(
-      *scene, *region, *view3d, *eval_object, grease_pencil->get_active_layer());
-  const float3 position = placement.project(mval);
-  const float pixel_size = ED_view3d_pixel_size(
-      rv3d, math::transform_point(placement.to_world_space(), position));
-  return brush->unprojected_radius / pixel_size;
-}
-
 static void radial_control_set_initial_mouse(bContext *C, RadialControl *rc, const wmEvent *event)
 {
   float d[2] = {0, 0};
@@ -2635,18 +2609,6 @@ static void radial_control_set_initial_mouse(bContext *C, RadialControl *rc, con
     d[0] *= zoom[0];
     d[1] *= zoom[1];
   }
-  rc->scale_fac = 1.0f;
-  if (rc->ptr.owner_id && GS(rc->ptr.owner_id->name) == ID_BR && rc->prop == &rna_Brush_size) {
-    Brush *brush = reinterpret_cast<Brush *>(rc->ptr.owner_id);
-    if ((brush && brush->gpencil_settings) && (brush->ob_mode == OB_MODE_PAINT_GREASE_PENCIL) &&
-        (brush->gpencil_brush_type == GPAINT_BRUSH_TYPE_DRAW) &&
-        (brush->flag & BRUSH_LOCK_SIZE) != 0)
-    {
-      const float radius_px = grease_pencil_unprojected_brush_radius_pixel_size(
-          C, brush, blender::float2(event->mval));
-      rc->scale_fac = max_ff(radius_px, 1.0f) / max_ff(rc->initial_value, 1.0f);
-    }
-  }
 
   rc->initial_mouse[0] -= d[0];
   rc->initial_mouse[1] -= d[1];
@@ -2852,9 +2814,6 @@ static void radial_control_paint_cursor(bContext * /*C*/, int x, int y, void *cu
     GPU_matrix_scale_2fv(zoom);
   }
 
-  /* Apply scale correction (used by grease pencil brushes). */
-  GPU_matrix_scale_2f(rc->scale_fac, rc->scale_fac);
-
   /* Draw rotated texture. */
   radial_control_paint_tex(rc, tex_radius, alpha);