From cab4d6f724af701239cf2d00f44ca94fca623c1f Mon Sep 17 00:00:00 2001
From: Sean Kim <SeanCTKim@protonmail.com>
Date: Mon, 12 Aug 2024 18:25:45 +0200
Subject: [PATCH] Refactor: Restructure sculpt shape key updates

Pull Request: https://projects.blender.org/blender/blender/pulls/126161
---
 .../editors/sculpt_paint/mesh_brush_common.hh | 10 +++--
 source/blender/editors/sculpt_paint/sculpt.cc | 40 +++++++++----------
 2 files changed, 26 insertions(+), 24 deletions(-)

diff --git a/source/blender/editors/sculpt_paint/mesh_brush_common.hh b/source/blender/editors/sculpt_paint/mesh_brush_common.hh
index 64b349df879..754e3e9f0b8 100644
--- a/source/blender/editors/sculpt_paint/mesh_brush_common.hh
+++ b/source/blender/editors/sculpt_paint/mesh_brush_common.hh
@@ -383,10 +383,12 @@ void clip_and_lock_translations(const Sculpt &sd,
  * shape key positions must be kept in sync, and shape keys dependent on the active key must also
  * be modified.
  */
-void apply_translations_to_shape_keys(Object &object,
-                                      Span<int> verts,
-                                      Span<float3> translations,
-                                      MutableSpan<float3> positions_mesh);
+void update_shape_keys(Object &object,
+                       const Mesh &mesh,
+                       const KeyBlock &active_key,
+                       Span<int> verts,
+                       Span<float3> translations,
+                       Span<float3> positions_orig);
 
 /**
  * Currently the pbvh::Tree owns its own copy of deformed positions that needs to be updated to
diff --git a/source/blender/editors/sculpt_paint/sculpt.cc b/source/blender/editors/sculpt_paint/sculpt.cc
index a23d1fa0b82..bfc1ae01c2f 100644
--- a/source/blender/editors/sculpt_paint/sculpt.cc
+++ b/source/blender/editors/sculpt_paint/sculpt.cc
@@ -1493,9 +1493,9 @@ void restore_position_from_undo_step(Object &object)
               }
             }
 
-            if (BKE_keyblock_from_object(&object)) {
-              /* Update dependent shape keys back to their original */
-              apply_translations_to_shape_keys(object, verts, tls.translations, positions_orig);
+            if (const KeyBlock *active_key = BKE_keyblock_from_object(&object)) {
+              update_shape_keys(
+                  object, mesh, *active_key, verts, tls.translations, positions_orig);
             }
 
             BKE_pbvh_node_mark_positions_update(node);
@@ -7246,19 +7246,15 @@ void clip_and_lock_translations(const Sculpt &sd,
   }
 }
 
-void apply_translations_to_shape_keys(Object &object,
-                                      const Span<int> verts,
-                                      const Span<float3> translations,
-                                      const MutableSpan<float3> positions_orig)
+void update_shape_keys(Object &object,
+                       const Mesh &mesh,
+                       const KeyBlock &active_key,
+                       const Span<int> verts,
+                       const Span<float3> translations,
+                       const Span<float3> positions_orig)
 {
-  Mesh &mesh = *static_cast<Mesh *>(object.data);
-  KeyBlock *active_key = BKE_keyblock_from_object(&object);
-  if (!active_key) {
-    return;
-  }
-
-  MutableSpan active_key_data(static_cast<float3 *>(active_key->data), active_key->totelem);
-  if (active_key == mesh.key->refkey) {
+  const MutableSpan active_key_data(static_cast<float3 *>(active_key.data), active_key.totelem);
+  if (&active_key == mesh.key->refkey) {
     for (const int vert : verts) {
       active_key_data[vert] = positions_orig[vert];
     }
@@ -7267,11 +7263,10 @@ void apply_translations_to_shape_keys(Object &object,
     apply_translations(translations, verts, active_key_data);
   }
 
-  /* For relative keys editing of base should update other keys. */
   if (bool *dependent = BKE_keyblock_get_dependent_keys(mesh.key, object.shapenr - 1)) {
     int i;
     LISTBASE_FOREACH_INDEX (KeyBlock *, other_key, &mesh.key->block, i) {
-      if ((other_key != active_key) && dependent[i]) {
+      if ((other_key != &active_key) && dependent[i]) {
         MutableSpan<float3> data(static_cast<float3 *>(other_key->data), other_key->totelem);
         apply_translations(translations, verts, data);
       }
@@ -7313,12 +7308,17 @@ void write_translations(const Sculpt &sd,
 
   const Mesh &mesh = *static_cast<Mesh *>(object.data);
   const KeyBlock *active_key = BKE_keyblock_from_object(&object);
-  const bool relative_shapekey_active = active_key != nullptr && active_key != mesh.key->refkey;
-  if (!relative_shapekey_active) {
+  if (!active_key) {
+    apply_translations(translations, verts, positions_orig);
+    return;
+  }
+
+  const bool basis_shapekey_active = active_key == mesh.key->refkey;
+  if (basis_shapekey_active) {
     apply_translations(translations, verts, positions_orig);
   }
 
-  apply_translations_to_shape_keys(object, verts, translations, positions_orig);
+  update_shape_keys(object, mesh, *active_key, verts, translations, positions_orig);
 }
 
 void scale_translations(const MutableSpan<float3> translations, const Span<float> factors)