After the part

"GetF(0, ptr+56+BaseClass->MapOffset, sizeof(CUSTOMVERTEX)*NumVertices, &vertex[0]);"

Can't you just iterate through your vertices and swap the z and y components?

Such as

for(int i=0;i<NumVertices;++i)
{
std::swap(vertex[i].z,vertex[i].y);
}

Best regards!

After the part

"GetF(0, ptr+56+BaseClass->MapOffset, sizeof(CUSTOMVERTEX)*NumVertices, &vertex[0]);"

Can't you just iterate through your vertices and swap the z and y components?

Such as

for(int i=0;i<NumVertices;++i)
{
std::swap(vertex[i].z,vertex[i].y);
}

Best regards!