计算骨骼变形网格的AABB结果不准确，求排查解决

继此前相关提问后，参考社区帖子编写了考虑骨骼权重的代码，用于计算受Skeleton3D骨骼变形的MeshInstance3D的精确AABB，但最终结果并不精准，具体实现如下：

核心计算函数 #

func get_precise_aabb(mesh_instance : MeshInstance3D):
    
    # 获取网格数据
    var skeleton:Skeleton3D = mesh_instance.get_node_or_null(mesh_instance.skeleton)
    var data : Array = mesh_instance.mesh.surface_get_arrays(0)
    var vertices : Array =  data[Mesh.ARRAY_VERTEX]
    var bones: Array = data[Mesh.ARRAY_BONES]
    var weights: Array = data[Mesh.ARRAY_WEIGHTS]
    var bone_count :int = len(weights)/len(vertices)
    
    # 找出网格中极值顶点
    var low : Vector3 = Vector3.INF
    var high : Vector3 = -Vector3.INF
    for vert_idx in len(vertices):
        var vert = vertices[vert_idx]
        var deformed_transformation := Transform3D.IDENTITY
        
        for i in bone_count: # 对顶点应用骨骼加权变换
            var weight = weights[vert_idx * bone_count + i]
            var bone_idx = bones[vert_idx * bone_count + i]
            var bone_relative_transform = skeleton.get_bone_global_pose(bone_idx) * skeleton.get_bone_global_rest(bone_idx).inverse()
            var bone_frame_transform = Transform3D(
                lerp(Transform3D.IDENTITY.basis, bone_relative_transform.basis, weight),
                lerp(Transform3D.IDENTITY.origin, bone_relative_transform.origin, weight)
            )
            deformed_transformation = deformed_transformation * skeleton.global_transform * bone_frame_transform
        
        vert = deformed_transformation * vert
        
        low.x = min(low.x, vert.x)
        high.x = max(high.x, vert.x)
        low.y = min(low.y, vert.y)
        high.y = max(high.y, vert.y)
        low.z = min(low.z, vert.z)
        high.z = max(high.z, vert.z)
    
    return AABB(low, high - low)

Tool模式调用代码 #

@tool
extends Node3D

@export var btn: bool = false :set=set_bth

func set_bth(value: bool):
    if !value:
        return
    
    var precise_aabb = get_precise_aabb($Skeleton3D/Cube)
    var bounding_box = $BoundingBox
    bounding_box.scale = precise_aabb.size
    bounding_box.global_position = precise_aabb.position + precise_aabb.size / 2

问题现象 #

运行后生成的AABB与变形后的网格不匹配，编辑器截图显示包围盒的位置和大小存在明显偏差，已准备最小复现项目用于排查问题。

内容的提问来源于stack exchange，提问作者Manas R. Makde