Created a uv debugger tool.

game/tools/uv_debugger/UVDebugger.gd

@@ -0,0 +1,37 @@
+tool
+extends Control
+
+var _texture : Texture
+var _indices : PoolIntArray = PoolIntArray()
+var _uvs : PoolVector2Array = PoolVector2Array()
+
+func _draw():
+	if _texture:
+		draw_texture_rect_region(_texture, Rect2(Vector2(), get_size()), Rect2(Vector2(), _texture.get_size()))
+		
+	if _uvs.size() > 0:
+		var c : Color = Color(1, 1, 1, 1)
+		
+		for i in range(0, len(_indices), 3):
+			draw_line(_uvs[_indices[i]] * get_size(), _uvs[_indices[i + 1]] * get_size(), c, 1, false)
+			draw_line(_uvs[_indices[i + 1]] * get_size(), _uvs[_indices[i + 2]] * get_size(), c, 1, false)
+			draw_line(_uvs[_indices[i + 2]] * get_size(), _uvs[_indices[i]] * get_size(), c, 1, false)
+
+func set_texture(texture : Texture) -> void:
+	_texture = texture
+	update()
+
+func setup_from_mdr(mdr : MeshDataResource):
+	setup_from_arrays(mdr.array)
+	
+func setup_from_arrays(arrays : Array):
+	if arrays.size() != ArrayMesh.ARRAY_MAX:
+		return
+
+	if arrays[ArrayMesh.ARRAY_TEX_UV] == null:
+		return
+
+	_uvs = arrays[ArrayMesh.ARRAY_TEX_UV]
+	_indices = arrays[ArrayMesh.ARRAY_INDEX]
+
+	update()

game/tools/uv_debugger/UVDebugger.tscn

@@ -0,0 +1,8 @@
+[gd_scene load_steps=2 format=2]
+
+[ext_resource path="res://tools/uv_debugger/UVDebugger.gd" type="Script" id=1]
+
+[node name="UVDebugger" type="PanelContainer"]
+anchor_right = 1.0
+anchor_bottom = 1.0
+script = ExtResource( 1 )