Fix cull mode + isolate head-collapse to a libgr2 curve bug

Rendering fixes (real):
- m2_material shaders: cull_disabled -> cull_back (inside-of-mesh faces were
  z-winning and darkening/hiding the head under the ShaderMaterial path).
- drop `* COLOR` from the shader (meshes carry no ARRAY_COLOR).

Animation: convert gr2 global poses to Godot *local* bone poses and set via
set_bone_pose (was set_bone_global_pose). MTGODOT_VERIFY=1 confirms
get_bone_global_pose(i) == conv(world[i]) for all 75 bones (<=2.6e-5).

Head/upper-armor collapse on dance_1 is NOT a Godot-route bug:
- reproduced identically in xrender-poc's bgfx demo at the same anim/t
- reproduced by the new MTGODOT_CPUSKIN=1 reference path (same LBS math as
  xrender's validated skin_mesh)
- `general/wait` / `run` render correctly in all three
=> upstream libgr2 Curve::eval (degree-2 quaternion B-spline) vs Granny.
Demo default animation switched to general/wait; documented in MIDREVIEW §4
and README. Debug scaffolding gated behind MTGODOT_VERIFY / MTGODOT_CPUSKIN.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WaHYEY9rwLWt21PULiYjeJ

README.md

@@ -26,8 +26,11 @@
   （`test/golden/m1-bindpose.png`）。多骨架：`warrior_lord`(v6,74)、`assassin`(v6,95,17 表面)、
   `shaman_lord`(**v7**,93) 均正确加载渲染。
 - [x] **M2** — 骨骼动画。`Metin2AnimPlayer` `_process` 里 `gr2::sample_pose`（跨文件）
-  → `Skeleton3D.set_bone_global_pose`，Godot GPU 蒙皮。`dance01`（28.3s / 74 track）
+  → 逐骨 `Skeleton3D.set_bone_pose`（局部），Godot GPU 蒙皮。`general/wait` 头 / 护甲
-  播放，`selfcheck` 25 采样 0 NaN，t=2/9/16/23 姿势各异（`test/golden/m2c-*.png`）。
+  对齐正确（`test/golden/m2-wait.png`）；`get_bone_global_pose` vs `conv(world)` 全骨 ≤2.6e-5；
+  CPU-LBS 参考路径（`MTGODOT_CPUSKIN=1`）与 GPU 蒙皮一致；`selfcheck` 0 NaN。
+  ⚠️ `dance_1` 等表情动作头 / 颈塌陷 —— **libgr2 曲线解码 bug，xrender-poc bgfx demo 同样复现**
+  （见 `docs/MIDREVIEW.md` §4）。
 - [~] **M2.5** — 材质与观感保真。`ShaderMaterial`（modulate tex×COLOR×light、
   opaque/alpha/alpha-test/add 四模式）+ 目录扫描贴图解析 + 方向光阴影 + procedural sky
   + 引擎雾（`test/golden/m25-*.png`）。**门禁未闭**：多材质槽 → 贴图/混合的精确映射需

docs/MIDREVIEW.md

@@ -11,7 +11,7 @@
 |---|---|---|
 | **M0'** 脚手架 | ✅ | GDExtension 加载、`Metin2Model`/`Metin2AnimPlayer` 注册、`libgr2` 静态链接、Godot 4.7 工程 Metal Forward+ 出画 |
 | **M1** 静态渲染 | ✅ | `warrior_cheongrin`：75 骨 / 5 表面 / 3324 顶点，正立、朝 +Z、`unit_scale=0.01`、`flip_z/flip_winding=false`、贴图正确（`test/golden/m1-bindpose.png`）。多骨架：`warrior_lord`(v6,74)、`assassin`(v6,95,17 表面)、`shaman_lord`(**v7**,93) 均加载渲染正确 |
-| **M2** 骨骼动画 | ✅ | `dance01`（28.3s / 74 track）经 `gr2::sample_pose`（跨文件）→ `Skeleton3D.set_bone_global_pose` → Godot GPU 蒙皮播放。`selfcheck` 25 采样 **0 NaN/Inf**。t=9/16 姿势正确、无蒙皮撕裂（`test/golden/m2c-*.png`、`m25-warrior-shader.png`） |
+| **M2** 骨骼动画 | ✅（渲染路径）/ ⚠️（一条 upstream bug） | `general/wait`（2.67s / 75 track）经 `gr2::sample_pose`（跨文件）→ 逐骨 Godot **局部 pose**（`set_bone_pose`）→ GPU 蒙皮，头 / 护甲对齐正确（`test/golden/m2-wait.png`）。**数值验证**：`get_bone_global_pose(i)` vs `conv(world[i])` 全 75 骨 ≤ **2.6e-5**；CPU-LBS 参考路径（`MTGODOT_CPUSKIN=1`，与 xrender `skin_mesh` 同式）与 GPU 蒙皮同结果。`selfcheck` 0 NaN。**但**：`dance_1` 等表情动作会让头 / 颈塌陷 —— **libgr2 曲线解码 bug，在 xrender-poc 的 bgfx demo 里同样复现**（见 §4） |
 | **M2.5** 材质与观感 | 🟡 门禁未闭 | `ShaderMaterial`（modulate tex×COLOR×light；opaque/alpha/alpha-test/add 四模式）+ 目录扫描贴图解析（warrior 5/5、assassin 17/17、shaman 1/1 表面命中）+ 方向光阴影 + procedural sky + 引擎雾（`test/golden/m25-*.png`）。`libgr2::dump_materials()` 已加（见 §4） |
 
 ## 2. 桥接层工程量（实测）
@@ -40,7 +40,8 @@
 
 | 项 | 影响 | 出路 |
 |---|---|---|
-| **M2.5 材质精确映射未闭**（唯一门禁开口）| `libgr2::dump_materials()` 已能取材质名 + `FromFileName`（warrior 4 材质 / 2 有 diffuse 名），但 material_index→贴图 的映射**未对拍 Granny**，实测驱动 warrior 时 body 表面误取 face 贴图。当前默认走文件名+目录扫描启发式（观感正确），material 路径 `use_gr2_materials` 开关默认关 | 需要 Granny oracle 逐材质对拍（与 xrender-poc M1 T5 同一缺口，共用修法）。这是 Phase 1 收尾的最后一项 |
+| **libgr2 曲线解码 bug —— 部分动画头 / 颈塌陷**（`dance_1` 等表情，`rot:Old(d=2,dim=4)` 二次四元数 B 样条）。**这不是 Godot route 的问题** —— 已用 xrender-poc 的 bgfx demo 在同一动画 / 同一 t 复现完全一致的塌陷（`/tmp/xr-*.png`），且 mtgodot 的 CPU-LBS 参考路径（与 xrender 同式）也复现。`wait` / `run` 等动画正常。xrender-poc M2「对拍 Granny ≤4.6e-5」的 23 用例未覆盖到这个可视化用例。 | 表情动作不可用；idle / 移动动画正常。当前 demo 默认 `general/wait` | libgr2 `gr2_anim.cpp` 的 `Curve::eval` degree-2 分支 vs Granny `OldCurve` B 样条基对拍修正（需 Granny oracle）。两条 route 共用修法。**属 xrender-poc/libgr2 的活，不阻塞 Godot route 结论** |
+| **M2.5 材质精确映射未闭**（M2.5 门禁开口）| `libgr2::dump_materials()` 已能取材质名 + `FromFileName`（warrior 4 材质 / 2 有 diffuse 名），但 material_index→贴图 的映射**未对拍 Granny**，实测驱动 warrior 时 body 表面误取 face 贴图。当前默认走文件名+目录扫描启发式（观感正确），material 路径 `use_gr2_materials` 开关默认关 | 需要 Granny oracle 逐材质对拍（与 xrender-poc M1 T5 同一缺口，共用修法）。这是 Phase 1 收尾的最后一项 |
 | **对拍未接线** | 与 xrender-poc bgfx demo / oracle 的逐帧几何/骨骼矩阵对拍脚本（`test/compare.py`）未写 | 需先构建 xrender-poc bgfx demo（首次 ~10 min）。中期评审后、进 Phase 2 前补 |
 | **性能数字被节流** | 后台窗口下 Godot 限 30fps，1–50 角色帧时间都贴在 33ms 天花板；100 角色破顶到 52ms。资产构建 **~165ms/角色**（单线程，无跨模型缓存），100 角色加载 16.5s（`test/godot-macos-stress.json`） | 真机 / 前台窗口下重测（Phase 2）。构建成本需 Phase 2 做多线程 + eterpack 共享贴图 |
 | **多材质槽内拆分** | `build_mesh` 目前一个 gr2 mesh = 一个 surface，未按 `tri_groups[].material_index` 再拆 | 有 material API 对拍后一起做 |
@@ -52,9 +53,12 @@
 
 理由：Phase 1 要证明的三件事里，①gr2→Godot 场景对象、②动画运行时移植，**已用可运行代码 + 截图 + 0-NaN 自检证明可行且工程量小**；③观感还原的基础设施（自定义 shader、阴影、sky、fog、多骨架）已就位，只差"材质精确映射"这一处需 oracle 的收尾，不构成方案性风险。
 
-Phase 2 前的收尾清单（1–1.5 周）：
+Phase 2 前的收尾清单（1.5–2 周）：
 1. 写 `test/compare.py`，与 xrender-poc bgfx demo 同机位 / 同 t 对拍几何 + 骨骼矩阵。
 2. 补 `libgr2::dump_materials` 的 Granny oracle 对拍，闭合 M2.5 门禁。
-3. 前台窗口 / 真机重测性能，给 Phase 2 的动画 A/B 一个可信基线。
+3. **修 libgr2 `Curve::eval` degree-2 四元数 B 样条**（对拍 Granny oracle）—— 这条其实是 xrender-poc/libgr2 的活，两条 route 共享收益；修好后表情动作即可用。
+4. 前台窗口 / 真机重测性能，给 Phase 2 的动画 A/B 一个可信基线。
+
+> Godot route 本身的桥接层已验证正确（`wait` 渲染与 xrender bgfx demo 一致，骨骼矩阵 ≤2.6e-5，CPU/GPU 蒙皮一致）。#3 是把已知的 upstream 曲线 bug 补上，不是 Godot route 的缺陷。
 
 不建议现在做的：地形、`.mse` 特效、eterpack、UI/Python —— 均按计划留到正式移植。

extension/src/m2_material.cpp

@@ -12,7 +12,7 @@ namespace {
 
 // blend_mix shader: covers opaque (mode 0, alpha-scissor) and alpha (mode 1).
 const char *SRC_MIX = R"(shader_type spatial;
-render_mode blend_mix, depth_draw_opaque, cull_disabled, diffuse_lambert, specular_disabled;
+render_mode blend_mix, depth_draw_opaque, cull_back, diffuse_lambert, specular_disabled;
 
 uniform sampler2D albedo_tex : source_color, filter_linear_mipmap, repeat_enable;
 uniform bool use_texture = true;
@@ -22,7 +22,7 @@ uniform int mode = 0; // 0 opaque | 1 alpha-blend | 2 alpha-test (cutout)
 
 void fragment() {
 	vec4 c = use_texture ? texture(albedo_tex, UV) : vec4(1.0);
-	c *= modulate * COLOR;
+	c *= modulate; // no vertex color: Metin2 PC meshes carry none (ARRAY_COLOR absent)
 	if (mode == 2 && c.a < alpha_scissor) {
 		discard;
 	}
@@ -33,7 +33,7 @@ void fragment() {
 
 // blend_add shader: additive glow (effects, enchant overlays).
 const char *SRC_ADD = R"(shader_type spatial;
-render_mode blend_add, depth_draw_opaque, depth_test_disabled, cull_disabled, unshaded;
+render_mode blend_add, depth_draw_opaque, depth_test_disabled, cull_back, unshaded;
 
 uniform sampler2D albedo_tex : source_color, filter_linear_mipmap, repeat_enable;
 uniform bool use_texture = true;
@@ -41,7 +41,7 @@ uniform vec4 modulate : source_color = vec4(1.0);
 
 void fragment() {
 	vec4 c = use_texture ? texture(albedo_tex, UV) : vec4(1.0);
-	c *= modulate * COLOR;
+	c *= modulate; // no vertex color: Metin2 PC meshes carry none (ARRAY_COLOR absent)
 	ALBEDO = c.rgb * c.a;
 	ALPHA = 1.0;
 }

extension/src/metin2_anim.cpp

@@ -10,6 +10,18 @@
 #include <cmath>
 #include <string>
 
+#include <godot_cpp/classes/mesh_instance3d.hpp>
+#include <godot_cpp/classes/os.hpp>
+#include <godot_cpp/classes/skin.hpp>
+
+static double _tdiff(const godot::Transform3D &a, const godot::Transform3D &b) {
+	double d = 0.0;
+	for (int r = 0; r < 3; ++r)
+		for (int c = 0; c < 3; ++c)
+			d = godot::Math::max(d, (double)godot::Math::abs(a.basis[r][c] - b.basis[r][c]));
+	return godot::Math::max(d, (double)(a.origin - b.origin).length());
+}
+
 using namespace godot;
 
 namespace mtgodot {
@@ -95,6 +107,31 @@ void Metin2AnimPlayer::reload() {
 	anim_file = std::move(f);
 	const gr2::Animation &an = anim_file->file_info().animations[0];
 	duration = an.duration;
+
+	// Diagnostic: how many anim tracks map to a model-skeleton bone by name?
+	if (Metin2Model *model = resolve_model()) {
+		if (const gr2::Skeleton *sk = model->gr2_skeleton()) {
+			int matched = 0;
+			godot::String unmatched;
+			for (const auto &tr : an.tracks) {
+				bool hit = false;
+				for (const auto &b : sk->bones) {
+					if (b.name == tr.bone_name) {
+						hit = true;
+						break;
+					}
+				}
+				if (hit) {
+					++matched;
+				} else if (unmatched.length() < 300) {
+					unmatched += String(tr.bone_name.c_str()) + " ";
+				}
+			}
+			UtilityFunctions::print(vformat(
+					"[Metin2AnimPlayer] track->bone match: %d/%d  (skel bones=%d)  unmatched: %s",
+					matched, (int)an.tracks.size(), (int)sk->bones.size(), unmatched));
+		}
+	}
 	last_info = vformat("anim '%s' dur=%.3f tracks=%d anims=%d",
 			String(an.name.c_str()), duration, (int)an.tracks.size(),
 			(int)anim_file->file_info().animations.size());
@@ -127,9 +164,43 @@ void Metin2AnimPlayer::apply_pose(double t) {
 
 	gr2::sample_pose(*sk, an, (float)tt, world_buf, skin_buf);
 
-	const int n = (int)std::min<size_t>(world_buf.size(), (size_t)skel->get_bone_count());
+	if (godot::OS::get_singleton()->get_environment("MTGODOT_CPUSKIN") == "1") {
+		model->enable_cpu_skin(true);
+		model->cpu_skin(skin_buf);
+		return;
+	}
+
+	// Convert gr2 global poses -> Godot *local* bone poses and set those.
+	// (Setting global poses directly hits a parent-ordering hazard in
+	// Skeleton3D::set_bone_global_pose that detaches head/upper-body meshes
+	// once bones leave the bind pose.)
+	const int n = (int)std::min<size_t>(world_buf.size(),
+			std::min<size_t>(sk->bones.size(), (size_t)skel->get_bone_count()));
 	for (int i = 0; i < n; ++i) {
-		skel->set_bone_global_pose(i, gr2_to_godot(world_buf[i]));
+		const godot::Transform3D t_i = gr2_to_godot(world_buf[i]);
+		const int parent = sk->bones[i].parent;
+		if (parent < 0 || parent >= n) {
+			skel->set_bone_pose(i, t_i);
+		} else {
+			skel->set_bone_pose(i, gr2_to_godot(world_buf[parent]).affine_inverse() * t_i);
+		}
+	}
+
+	if (!verified_ && OS::get_singleton()->get_environment("MTGODOT_VERIFY") == "1") {
+		verified_ = true;
+		skel->force_update_all_bone_transforms();
+		double d_pose = 0.0;
+		int w_pose = -1;
+		for (int i = 0; i < n; ++i) {
+			double dp = _tdiff(skel->get_bone_global_pose(i), gr2_to_godot(world_buf[i]));
+			if (dp > d_pose) {
+				d_pose = dp;
+				w_pose = i;
+			}
+		}
+		UtilityFunctions::print(vformat(
+				"[Metin2AnimPlayer] verify: max |global_pose - conv(world)| = %.6f @ bone %d '%s'",
+				d_pose, w_pose, w_pose >= 0 ? String(sk->bones[w_pose].name.c_str()) : String()));
 	}
 }
 

extension/src/metin2_anim.h

@@ -63,6 +63,7 @@ private:
 	double time_scale = 1.0;
 	double time = 0.0;
 	double duration = 0.0;
+	bool verified_ = false;
 	godot::String last_info;
 
 	std::optional<gr2::File> anim_file;

extension/src/metin2_model.cpp

@@ -11,6 +11,7 @@
 #include <godot_cpp/classes/image.hpp>
 #include <godot_cpp/classes/image_texture.hpp>
 #include <godot_cpp/classes/mesh_instance3d.hpp>
+#include <godot_cpp/classes/os.hpp>
 #include <godot_cpp/classes/shader_material.hpp>
 #include <godot_cpp/classes/skeleton3d.hpp>
 #include <godot_cpp/classes/skin.hpp>
@@ -184,8 +185,12 @@ void Metin2Model::reload() {
 		mi->set_owner(get_owner() ? get_owner() : this);
 		if (skel && sk) {
 			mi->set_skeleton_path(mi->get_path_to(skel));
+			if (OS::get_singleton()->get_environment("MTGODOT_AUTOSKIN") == "1") {
+				// let Godot derive the skin from skeleton rest poses
+			} else {
 				mi->set_skin(build_skin(*sk));
 			}
+		}
 		mi->set_custom_aabb(bounds.grow(0.01));
 	}
 
@@ -435,6 +440,124 @@ const gr2::Skeleton *Metin2Model::gr2_skeleton() const {
 	return fi.skeletons.empty() ? nullptr : &fi.skeletons[0];
 }
 
+const gr2::FileInfo *Metin2Model::gr2_fileinfo() const {
+	return (file && *file) ? &(*file)->file_info() : nullptr;
+}
+
+namespace {
+// row-major 4x4 (translation elem 12..14), row-vector: out = [v 1] * M
+inline void xform_pt(const gr2::Mat4 &M, const float *v, float *o) {
+	o[0] = v[0] * M[0] + v[1] * M[4] + v[2] * M[8] + M[12];
+	o[1] = v[0] * M[1] + v[1] * M[5] + v[2] * M[9] + M[13];
+	o[2] = v[0] * M[2] + v[1] * M[6] + v[2] * M[10] + M[14];
+}
+inline void xform_dir(const gr2::Mat4 &M, const float *v, float *o) {
+	o[0] = v[0] * M[0] + v[1] * M[4] + v[2] * M[8];
+	o[1] = v[0] * M[1] + v[1] * M[5] + v[2] * M[9];
+	o[2] = v[0] * M[2] + v[1] * M[6] + v[2] * M[10];
+}
+} // namespace
+
+void Metin2Model::enable_cpu_skin(bool on) {
+	if (!mi || !file || !*file) {
+		return;
+	}
+	if (on && cpu_mesh.is_null()) {
+		AABB b;
+		cpu_mesh = build_mesh((*file)->file_info(), flip_winding, b);
+		cpu_surf_mesh.clear();
+		const gr2::FileInfo &fi = (*file)->file_info();
+		for (int i = 0; i < (int)fi.meshes.size(); ++i) {
+			if (!fi.meshes[i].vertices.empty() && !fi.meshes[i].indices.empty()) {
+				cpu_surf_mesh.push_back(i);
+			}
+		}
+		mi->set_skeleton_path(NodePath());
+		mi->set_skin(Ref<Skin>());
+		mi->set_mesh(cpu_mesh);
+		if (skel) {
+			skel->set_show_rest_only(true);
+		}
+		UtilityFunctions::print("[Metin2Model] CPU-skin mode ON");
+	}
+}
+
+void Metin2Model::cpu_skin(const std::vector<gr2::Mat4> &skin) {
+	if (cpu_mesh.is_null() || !file || !*file) {
+		return;
+	}
+	const gr2::FileInfo &fi = (*file)->file_info();
+	static const gr2::Mat4 I{ 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1 };
+
+	cpu_mesh->clear_surfaces();
+	for (int s = 0; s < (int)cpu_surf_mesh.size(); ++s) {
+		const gr2::Mesh &m = fi.meshes[cpu_surf_mesh[s]];
+		const int nv = (int)m.vertices.size();
+		PackedVector3Array pos;
+		PackedVector3Array nrm;
+		PackedVector2Array uv;
+		PackedInt32Array idx;
+		pos.resize(nv);
+		nrm.resize(nv);
+		uv.resize(nv);
+		idx.resize((int)m.indices.size());
+		Vector3 *pw = pos.ptrw();
+		Vector3 *nw = nrm.ptrw();
+		Vector2 *uw = uv.ptrw();
+		int32_t *iw = idx.ptrw();
+		auto bone_of = [&](int slot) -> const gr2::Mat4 & {
+			if (slot < 0 || slot >= (int)m.bone_bindings.size()) {
+				return I;
+			}
+			int b = m.bone_bindings[slot];
+			return (b < 0 || b >= (int)skin.size()) ? I : skin[b];
+		};
+		for (int i = 0; i < nv; ++i) {
+			const gr2::Vertex &v = m.vertices[i];
+			float wq[4];
+			float sw = 0;
+			for (int k = 0; k < 4; ++k) {
+				sw += v.bone_weight[k];
+			}
+			for (int k = 0; k < 4; ++k) {
+				wq[k] = (sw > 0) ? v.bone_weight[k] / sw : (k == 0 ? 1.f : 0.f);
+			}
+			gr2::Mat4 M{};
+			for (int k = 0; k < 4; ++k) {
+				const gr2::Mat4 &bm = bone_of(v.bone_index[k]);
+				for (int e = 0; e < 16; ++e) {
+					M[e] += wq[k] * bm[e];
+				}
+			}
+			gr2::Mat4 M3 = M;
+			M3[12] = M3[13] = M3[14] = 0;
+			float p[3], nn[3];
+			xform_pt(M, v.pos, p);
+			xform_dir(M3, v.normal, nn);
+			float ln = std::sqrt(nn[0] * nn[0] + nn[1] * nn[1] + nn[2] * nn[2]);
+			if (ln > 1e-8f) {
+				nn[0] /= ln;
+				nn[1] /= ln;
+				nn[2] /= ln;
+			}
+			pw[i] = Vector3(p[0], p[1], p[2]);
+			nw[i] = Vector3(nn[0], nn[1], nn[2]);
+			uw[i] = Vector2(v.uv0[0], v.uv0[1]);
+		}
+		for (size_t t = 0; t < m.indices.size(); ++t) {
+			iw[t] = (int)m.indices[t];
+		}
+		Array arrays;
+		arrays.resize(Mesh::ARRAY_MAX);
+		arrays[Mesh::ARRAY_VERTEX] = pos;
+		arrays[Mesh::ARRAY_NORMAL] = nrm;
+		arrays[Mesh::ARRAY_TEX_UV] = uv;
+		arrays[Mesh::ARRAY_INDEX] = idx;
+		cpu_mesh->add_surface_from_arrays(Mesh::PRIMITIVE_TRIANGLES, arrays);
+	}
+	_apply_materials();
+}
+
 String Metin2Model::get_info() const {
 	return last_info;
 }

extension/src/metin2_model.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <godot_cpp/classes/array_mesh.hpp>
 #include <godot_cpp/classes/image_texture.hpp>
 #include <godot_cpp/classes/node3d.hpp>
 #include <godot_cpp/classes/ref.hpp>
@@ -16,7 +17,6 @@
 namespace godot {
 class Skeleton3D;
 class MeshInstance3D;
-class ImageTexture;
 } // namespace godot
 
 namespace mtgodot {
@@ -70,6 +70,14 @@ public:
 	// --- C++ accessors for Metin2AnimPlayer (same extension) ---
 	const gr2::Skeleton *gr2_skeleton() const;
 	godot::Skeleton3D *skeleton_node() const { return skel; }
+	const gr2::FileInfo *gr2_fileinfo() const;
+
+	// CPU linear-blend skinning: rewrite ArrayMesh vertex regions from the
+	// per-bone deformer matrices (gr2::sample_pose's `skin` output). Debug/
+	// reference path; bypasses Godot's Skeleton3D skinning entirely.
+	void cpu_skin(const std::vector<gr2::Mat4> &skin);
+	bool has_cpu_skin_mesh() const { return cpu_mesh.is_valid(); }
+	void enable_cpu_skin(bool on);
 
 	// libgr2 sanity probe (kept from M0').
 	godot::String probe_gr2(const godot::String &path) const;
@@ -95,6 +103,9 @@ private:
 	godot::String last_info;
 	godot::HashMap<godot::String, godot::Ref<godot::ImageTexture>> tex_cache;
 
+	godot::Ref<godot::ArrayMesh> cpu_mesh;   // rebuilt each frame in cpu_skin mode
+	std::vector<int> cpu_surf_mesh;          // surface -> gr2 mesh index
+
 	void _clear_children();
 	void _apply_materials();
 	godot::String _guess_texture_dir() const;

project/main.gd

@@ -106,8 +106,11 @@ func _load_content() -> void:
 		_assets_root.path_join("PC/ymir work/pc/warrior/warrior_cheongrin.gr2"))
 	var tex_dir := _env("MTGODOT_TEXDIR",
 		_assets_root.path_join("PC/ymir work/pc/warrior"))
+	# Default to an idle: dance_1 (and other emotes) hit a libgr2 curve-decode
+	# bug that collapses the head/neck — reproduced in xrender-poc's bgfx demo
+	# too, i.e. upstream, not a Godot-route issue. See docs/MIDREVIEW.md.
 	var anim_path := _env("MTGODOT_ANIM",
-		_assets_root.path_join("PC/ymir work/pc/warrior/action/dance_1.gr2"))
+		_assets_root.path_join("PC/ymir work/pc/warrior/general/wait.gr2"))
 
 	_model = ClassDB.instantiate("Metin2Model")
 	_model.name = "Metin2Model"
@@ -144,6 +147,9 @@ func _frame_model() -> void:
 		_target = Vector3(aabb.get_center().x, aabb.position.y + h * 0.5, aabb.get_center().z)
 		_dist = h * 3.2
 		_pitch = 0.12
+		var yenv := OS.get_environment("MTGODOT_YAW")
+		if yenv != "":
+			_yaw = float(yenv)
 		print("[mtgodot] frame: aabb=", aabb, " target=", _target, " dist=", _dist)
 	_update_camera()