Revert "Fix #127398 : Transform tool not working correctly with non-uniform scaling"

This reverts commit 7375b837b0.

This commit causes issues with non-global transform orientations and
with hindsight now seems like the incorrect approach to take, given that
the original issue is specifically about non-uniform scale.

Pull Request: https://projects.blender.org/blender/blender/pulls/156055

source/blender/editors/sculpt_paint/mesh/sculpt_transform.cc

@@ -83,14 +83,13 @@ void init_transform(bContext *C, Object &ob, const float mval_fl[2], const char
   }
 }
 
-static std::array<float4x4, 8> transform_matrices_init(const Object &ob,
-                                                       const SculptSession &ss,
+static std::array<float4x4, 8> transform_matrices_init(const SculptSession &ss,
                                                        const ePaintSymmetryFlags symm,
                                                        const TransformDisplacementMode t_mode)
 {
   std::array<float4x4, 8> mats;
 
-  float3 d_s;
+  float3 final_pivot_pos, d_t, d_s;
   float d_r[4];
   float t_mat[4][4], r_mat[4][4], s_mat[4][4], pivot_mat[4][4], pivot_imat[4][4],
       transform_mat[4][4];
@@ -108,20 +107,11 @@ static std::array<float4x4, 8> transform_matrices_init(const Object &ob,
       copy_v3_v3(start_pivot_scale, ss.prev_pivot_scale);
       break;
   }
-  const float4x4 &ob_to_world = ob.object_to_world();
-  const float4x4 &world_to_ob = ob.world_to_object();
 
   for (int i = 0; i < PAINT_SYMM_AREAS; i++) {
     ePaintSymmetryAreas v_symm = ePaintSymmetryAreas(i);
 
-    const float3 final_pivot_pos = SCULPT_flip_v3_by_symm_area(
-        ss.pivot_pos, symm, v_symm, start_pivot_pos);
-
-    const float3 start_pivot_local = SCULPT_flip_v3_by_symm_area(
-        start_pivot_pos, symm, v_symm, ss.init_pivot_pos);
-
-    const float3 final_pivot_world = math::transform_point(ob_to_world, final_pivot_pos);
-    const float3 start_pivot_world = math::transform_point(ob_to_world, start_pivot_local);
+    copy_v3_v3(final_pivot_pos, ss.pivot_pos);
 
     unit_m4(pivot_mat);
 
@@ -130,8 +120,9 @@ static std::array<float4x4, 8> transform_matrices_init(const Object &ob,
     unit_m4(s_mat);
 
     /* Translation matrix. */
-    const float3 d_t_world = final_pivot_world - start_pivot_world;
-    translate_m4(t_mat, d_t_world.x, d_t_world.y, d_t_world.z);
+    sub_v3_v3v3(d_t, ss.pivot_pos, start_pivot_pos);
+    d_t = SCULPT_flip_v3_by_symm_area(d_t, symm, v_symm, ss.init_pivot_pos);
+    translate_m4(t_mat, d_t[0], d_t[1], d_t[2]);
 
     /* Rotation matrix. */
     sub_qt_qtqt(d_r, ss.pivot_rot, start_pivot_rot);
@@ -145,7 +136,8 @@ static std::array<float4x4, 8> transform_matrices_init(const Object &ob,
     size_to_mat4(s_mat, d_s);
 
     /* Pivot matrix. */
-    translate_m4(pivot_mat, final_pivot_world.x, final_pivot_world.y, final_pivot_world.z);
+    final_pivot_pos = SCULPT_flip_v3_by_symm_area(final_pivot_pos, symm, v_symm, start_pivot_pos);
+    translate_m4(pivot_mat, final_pivot_pos[0], final_pivot_pos[1], final_pivot_pos[2]);
     invert_m4_m4(pivot_imat, pivot_mat);
 
     /* Final transform matrix. */
@@ -153,9 +145,6 @@ static std::array<float4x4, 8> transform_matrices_init(const Object &ob,
     mul_m4_m4m4(transform_mat, transform_mat, s_mat);
     mul_m4_m4m4(mats[i].ptr(), transform_mat, pivot_imat);
     mul_m4_m4m4(mats[i].ptr(), pivot_mat, mats[i].ptr());
-    float temp[4][4];
-    mul_m4_m4m4(temp, mats[i].ptr(), ob_to_world.ptr());
-    mul_m4_m4m4(mats[i].ptr(), world_to_ob.ptr(), temp);
   }
 
   return mats;
@@ -301,7 +290,7 @@ static void sculpt_transform_all_vertices(const Depsgraph &depsgraph, const Scul
   const ePaintSymmetryFlags symm = SCULPT_mesh_symmetry_xyz_get(ob);
 
   std::array<float4x4, 8> transform_mats = transform_matrices_init(
-      ob, ss, symm, ss.filter_cache->transform_displacement_mode);
+      ss, symm, ss.filter_cache->transform_displacement_mode);
 
   /* Regular transform applies all symmetry passes at once as it is split by symmetry areas
    * (each vertex can only be transformed once by the transform matrix of its area). */
@@ -479,7 +468,7 @@ static void transform_radius_elastic(const Depsgraph &depsgraph,
   const ePaintSymmetryFlags symm = SCULPT_mesh_symmetry_xyz_get(ob);
 
   std::array<float4x4, 8> transform_mats = transform_matrices_init(
-      ob, ss, symm, ss.filter_cache->transform_displacement_mode);
+      ss, symm, ss.filter_cache->transform_displacement_mode);
 
   bke::pbvh::Tree &pbvh = *bke::object::pbvh_get(ob);
   const IndexMask &node_mask = ss.filter_cache->node_mask;

tests/files/sculpting/non_uniform_scaling_monkey.blend

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:eb09bf405d5f67681fed238e8514cc206bccdb872707f066d11afc390c5b25e9
-size 112699

tests/python/sculpt_paint/transform_operator_test.py

@@ -1,76 +0,0 @@
-# SPDX-FileCopyrightText: 2026 Blender Authors
-#
-# SPDX-License-Identifier: GPL-2.0-or-later
-
-__all__ = (
-    "main",
-)
-
-import unittest
-import sys
-import pathlib
-
-import bpy
-
-"""
-blender -b --factory-startup --python tests/python/sculpt_paint/transform_operator_test.py -- --testdir tests/files/sculpting/
-"""
-
-args = None
-
-# TODO: Current test should be rewritten with Mesh comparison
-# framework(see voxel_remesh_compare_test.py) to reduce the amount of
-# code, once framework supports context override.
-
-
-class TransformTest(unittest.TestCase):
-    def setUp(self):
-        bpy.ops.wm.open_mainfile(filepath=str(args.testdir / "non_uniform_scaling_monkey.blend"), load_ui=False)
-
-    def test_scaling_and_rotating_in_sculpt_mode(self):
-        test_monkey = bpy.data.objects['test_Monkey']
-        expected_monkey = bpy.data.objects['Expected_test_Monkey']
-
-        bpy.context.view_layer.objects.active = test_monkey
-
-        window = bpy.context.window_manager.windows[0]
-        viewarea_3D = next(area for area in window.screen.areas if area.type == 'VIEW_3D')
-        window_region = next(region for region in viewarea_3D.regions if region.type == 'WINDOW')
-        override_context = {
-            "window": window,
-            "area": viewarea_3D,
-            "region": window_region,
-            "space_data": viewarea_3D.spaces.active,
-            "region_data": viewarea_3D.spaces.active.region_3d,
-            "active_object": test_monkey,
-            "object": test_monkey
-        }
-
-        bpy.ops.ed.undo_push('EXEC_DEFAULT')
-        with bpy.context.temp_override(**override_context):
-            bpy.ops.object.mode_set(mode='SCULPT')
-            bpy.ops.transform.rotate(value=1.5708, orient_axis='Y', orient_type='GLOBAL')
-            bpy.ops.object.mode_set(mode='OBJECT')
-
-        result = expected_monkey.data.unit_test_compare(mesh=test_monkey.data)
-        self.assertEqual(result, 'Same')
-
-
-def main():
-    global args
-    import argparse
-
-    argv = [sys.argv[0]]
-    if '--' in sys.argv:
-        argv += sys.argv[sys.argv.index('--') + 1:]
-
-    parser = argparse.ArgumentParser()
-    parser.add_argument('--testdir', required=True, type=pathlib.Path)
-
-    args, remaining = parser.parse_known_args(argv)
-
-    unittest.main(argv=remaining)
-
-
-if __name__ == '__main__':
-    main()