From 8e0050f06530b9b390bbd1246f6a86cfa1e136a0 Mon Sep 17 00:00:00 2001
From: "YITSUSE, Masami" <MasamiYitsuse@github.com>
Date: Tue, 23 Jun 2026 15:59:18 +0900
Subject: [PATCH] revert(player): remove instance nesting depth guard

Drop the MAX_INSTANCE_DEPTH (16) cyclic/runaway-nesting guard added in
9e6d469. Per review, a cyclic Instance reference (A -> B -> A) is an
authoring mistake in the data, not something the player should guard
against, so the player no longer caps Instance nesting depth.

Removes `_instance_depth`, `MAX_INSTANCE_DEPTH`, the
setInstanceDepth/getInstanceDepth accessors, the depth check and the
warning skip in `_setup_instance_children`, and the child depth
propagation. Intentionally diverges from the Unity player's
MaxInstanceDepth. The audio signal from 9e6d469 is unrelated and kept.
---
 ss_player/ss_internal_player.cpp | 15 +--------------
 ss_player/ss_internal_player.h   | 11 -----------
 2 files changed, 1 insertion(+), 25 deletions(-)

diff --git a/ss_player/ss_internal_player.cpp b/ss_player/ss_internal_player.cpp
index d84c38c..e51d7cf 100644
--- a/ss_player/ss_internal_player.cpp
+++ b/ss_player/ss_internal_player.cpp
@@ -1355,15 +1355,6 @@ void SsInternalPlayer::_setup_instance_children() {
         auto pt = p->part_type_as_PartTypeInstance();
         if (!pt) continue;
 
-        // Cyclic / runaway-nesting guard: instance children live one level
-        // deeper than this player. Refuse to descend past MAX_INSTANCE_DEPTH so
-        // a cyclic reference (A → B → A authoring mistake) can't recurse until
-        // the stack overflows on load.
-        if (_instance_depth + 1 >= MAX_INSTANCE_DEPTH) {
-            WARN_PRINT(vformat("[SS] instance part %d: nesting exceeded %d levels; skipping to guard against cyclic references", i, MAX_INSTANCE_DEPTH));
-            continue;
-        }
-
         String pack_name = pt->ref_anime_pack() ? String::utf8(pt->ref_anime_pack()->c_str()) : String();
         String anim_name = pt->ref_anime_name() ? String::utf8(pt->ref_anime_name()->c_str()) : String();
         uint32_t pack_name_hash = pt->ref_anime_pack_hash();
@@ -1378,7 +1369,6 @@ void SsInternalPlayer::_setup_instance_children() {
 
         SsInternalPlayer* child = memnew(SsInternalPlayer);
         child->setParentDriven(true);
-        child->setInstanceDepth(_instance_depth + 1);
         child->setSubFrameEnabled(_sub_frame_enabled);
         // Hand the child the SSAB that actually contains the referenced
         // animation — may be `_ssabRes` itself or an external sibling.
@@ -2608,10 +2598,7 @@ void SsInternalPlayer::_fetchAnimation() {
     }
 
     // Recursive setup — instance children also populate their own
-    // `_instance_children`, so nested Instance parts are supported. Cross-SSAB
-    // cycles (A → B → A authoring mistakes) are bounded by MAX_INSTANCE_DEPTH:
-    // `_setup_instance_children` stops spawning children past that depth (with
-    // a warning) instead of recursing until the stack overflows on load.
+    // `_instance_children`, so nested Instance parts are supported.
     _setup_instance_children();
     _setup_effect_slots();
 
diff --git a/ss_player/ss_internal_player.h b/ss_player/ss_internal_player.h
index de72fff..0ce2ead 100644
--- a/ss_player/ss_internal_player.h
+++ b/ss_player/ss_internal_player.h
@@ -161,14 +161,6 @@ class SsInternalPlayer {
     void setParentDriven(bool p_enabled);
     bool isParentDriven() const { return _parent_driven; }
 
-    // Nesting depth within an Instance-part chain (0 = the root player the host
-    // owns). `_setup_instance_children` sets each spawned child to parent depth
-    // + 1 and refuses to descend past `MAX_INSTANCE_DEPTH`, guarding against
-    // cyclic Instance references (A → B → A authoring mistakes) that would
-    // otherwise recurse until the stack overflows on load.
-    void setInstanceDepth(int p_depth) { _instance_depth = p_depth; }
-    int getInstanceDepth() const { return _instance_depth; }
-
     // Per-tick update (in seconds; the host typically passes
     // `process_delta_time`). No-op when paused or in instance-child mode.
     void update(float delta_seconds);
@@ -328,9 +320,6 @@ class SsInternalPlayer {
     float _speed_rate = 1.0f;
     bool _sub_frame_enabled = false;
     bool _parent_driven = false;
-    int _instance_depth = 0;
-    // Hard cap on Instance-part nesting depth; see `setInstanceDepth`.
-    static constexpr int MAX_INSTANCE_DEPTH = 16;
 
     SsPlayerEventSink* _event_sink = nullptr;