M0' scaffold: Godot 4.7 + GDExtension + libgr2 wired up (macOS)

- extension/: godot-cpp submodule (master, API 4.7), Metin2Model node
  registered, links xrender-poc/libgr2 via sibling-dir reference.
- project/: Godot 4.7 project — orbit camera + DirectionalLight3D (shadows)
  + WorldEnvironment/procedural sky + placeholder cube; main.gd probes the
  extension and can run libgr2 on a real .gr2 (MTGODOT_PROBE_GR2).
- build.sh one-shot build into project/bin/.
- docs/GODOT-POC-PLAN.md (phased: Phase 1 macOS -> M0'/M1/M2/M2.5).

Verified on this machine:
  [mtgodot] Metin2Model registered OK — libgr2 linked
  probe_gr2(warrior_cheongrin.gr2) -> gr2 OK: format_version=6 sections=8
  Metal Forward+ renders the scene (test/golden/m0-scaffold.png).

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

project/main.gd

@@ -0,0 +1,125 @@
+extends Node3D
+## mtgodot-poc — M0' harness.
+##
+## Builds the minimal scene the plan asks for (orbit camera + DirectionalLight3D
+## with shadows + WorldEnvironment/sky + placeholder cube + an empty Metin2Model),
+## then reports whether the GDExtension loaded.
+##
+## M1 will replace the cube with Metin2Model.load_gr2(...) output.
+
+const ORBIT_SPEED := 0.01
+const ZOOM_STEP := 0.3
+const PITCH_LIMIT := 1.45
+
+var _cam: Camera3D
+var _yaw := 0.6
+var _pitch := 0.45
+var _dist := 4.0
+var _target := Vector3(0.0, 1.0, 0.0)
+var _dragging := false
+
+
+func _ready() -> void:
+	_build_environment()
+	_build_sun()
+	_build_camera()
+	_build_placeholder()
+	_probe_extension()
+	print("[mtgodot] M0' harness ready — drag: orbit, wheel: zoom, F2: screenshot")
+	# Batch capture: MTGODOT_AUTOSHOT=/abs/path.png godot --path project
+	var autoshot := OS.get_environment("MTGODOT_AUTOSHOT")
+	if autoshot != "":
+		await get_tree().create_timer(0.8).timeout
+		var img := get_viewport().get_texture().get_image()
+		img.save_png(autoshot)
+		print("[mtgodot] autoshot -> ", autoshot)
+		get_tree().quit()
+
+
+func _build_environment() -> void:
+	var we := WorldEnvironment.new()
+	var env := Environment.new()
+	var sky := Sky.new()
+	sky.sky_material = ProceduralSkyMaterial.new()
+	env.background_mode = Environment.BG_SKY
+	env.sky = sky
+	env.ambient_light_source = Environment.AMBIENT_SOURCE_SKY
+	env.tonemap_mode = Environment.TONE_MAPPER_FILMIC
+	we.environment = env
+	add_child(we)
+
+
+func _build_sun() -> void:
+	var sun := DirectionalLight3D.new()
+	sun.rotation_degrees = Vector3(-45.0, -35.0, 0.0)
+	sun.shadow_enabled = true
+	add_child(sun)
+
+
+func _build_camera() -> void:
+	_cam = Camera3D.new()
+	_cam.current = true
+	_cam.fov = 55.0
+	add_child(_cam)
+	_update_camera()
+
+
+func _build_placeholder() -> void:
+	var cube := MeshInstance3D.new()
+	cube.name = "Placeholder"
+	cube.mesh = BoxMesh.new()
+	cube.position = _target
+	add_child(cube)
+
+
+func _probe_extension() -> void:
+	if not ClassDB.class_exists("Metin2Model"):
+		push_error("[mtgodot] Metin2Model NOT registered — GDExtension failed to load")
+		return
+	var m := ClassDB.instantiate("Metin2Model") as Node3D
+	m.name = "Metin2Model"
+	add_child(m)
+	print("[mtgodot] Metin2Model registered OK — ", m.call("libgr2_info"))
+	# Optional: point MTGODOT_PROBE_GR2 at a real .gr2 to exercise libgr2 end to end.
+	var probe := OS.get_environment("MTGODOT_PROBE_GR2")
+	if probe != "":
+		print("[mtgodot] probe_gr2(", probe, ") -> ", m.call("probe_gr2", probe))
+
+
+func _update_camera() -> void:
+	var offset := Vector3(
+		cos(_pitch) * sin(_yaw),
+		sin(_pitch),
+		cos(_pitch) * cos(_yaw)) * _dist
+	_cam.position = _target + offset
+	_cam.look_at(_target, Vector3.UP)
+
+
+func _unhandled_input(event: InputEvent) -> void:
+	if event is InputEventMouseButton:
+		var mb := event as InputEventMouseButton
+		match mb.button_index:
+			MOUSE_BUTTON_LEFT:
+				_dragging = mb.pressed
+			MOUSE_BUTTON_WHEEL_UP:
+				_dist = maxf(0.5, _dist - ZOOM_STEP)
+				_update_camera()
+			MOUSE_BUTTON_WHEEL_DOWN:
+				_dist = minf(50.0, _dist + ZOOM_STEP)
+				_update_camera()
+	elif event is InputEventMouseMotion and _dragging:
+		var mm := event as InputEventMouseMotion
+		_yaw -= mm.relative.x * ORBIT_SPEED
+		_pitch = clampf(_pitch + mm.relative.y * ORBIT_SPEED, -PITCH_LIMIT, PITCH_LIMIT)
+		_update_camera()
+	elif event is InputEventKey:
+		var k := event as InputEventKey
+		if k.pressed and k.keycode == KEY_F2:
+			_screenshot()
+
+
+func _screenshot() -> void:
+	var img := get_viewport().get_texture().get_image()
+	var path := "user://shot_%d.png" % Time.get_ticks_msec()
+	img.save_png(path)
+	print("[mtgodot] screenshot -> ", ProjectSettings.globalize_path(path))