Function SortSkinBones

engine/modelc/src/modelimporter_gltf.cpp:1307–1368

}

static void SortSkinBones(Skin* skin)
{
    uint32_t bones_count = skin->m_Bones.Size();
    BoneSortInfo* infos = new BoneSortInfo[bones_count];

    uint32_t index_iter = 0;
    for (uint32_t i = 0; i < bones_count; ++i)
    {
        Bone* bone = &skin->m_Bones[i];
        if (bone->m_ParentIndex == INVALID_INDEX)
        {
            CalcIndicesDepthFirst(infos, bone, &index_iter);
        }
    }

    std::sort(infos, infos + bones_count, BoneInfoSortPred());

    // build the remap array
    InitSize(skin->m_BoneRemap, bones_count, bones_count);

    bool indices_differ = false;
    for (uint32_t i = 0; i < bones_count; ++i)
    {
        uint32_t index_old = infos[i].m_OldIndex;
        uint32_t index_new = infos[i].m_Index;
        skin->m_BoneRemap[index_old] = index_new;

        indices_differ |= index_old != index_new;
    }
    // If the indices don't differ, then we don't need to update the meshes bone indices either
    if (!indices_differ)
    {
        skin->m_BoneRemap.SetCapacity(0);
    }

    // do the remapping, i.e. flattern the hierarchy
    if (!skin->m_BoneRemap.Empty())
    {
        dmArray<uint32_t> bone_order;
        dmArray<Bone>     sorted_bones;
        InitSize(bone_order, bones_count, bones_count);
        InitSize(sorted_bones, bones_count, bones_count);

        for (uint32_t i = 0; i < bones_count; ++i)
        {
            bone_order[i] = i;
            Bone& bone = skin->m_Bones[i];
            bone.m_Index = skin->m_BoneRemap[bone.m_Index];
            bone.m_ParentIndex = bone.m_ParentIndex != INVALID_INDEX ? skin->m_BoneRemap[bone.m_ParentIndex] : INVALID_INDEX;
        }

        for (uint32_t i = 0; i < bones_count; ++i)
        {
            uint32_t new_index = skin->m_BoneRemap[i];
            CopyBone(&sorted_bones[new_index], &skin->m_Bones[i]);
        }

        skin->m_Bones.Swap(sorted_bones);