AddAttribute method
Implementation
void AddAttribute(String canonical, List data, int width) {
final bool instanced = canonical.codeUnitAt(0) == prefixInstancer;
if (instanced && _instances == 0) {
_instances = data.length ~/ width;
}
ChangeAttributeBuffer(canonical, _cgl.createBuffer());
ChangeAttributeData(canonical, data, width);
}