docs: public void setAttribute(int semantics, int ordinate, double value) {
  		_touch();
  		int ncomps = VertexDescription.getComponentCount(semantics);
  		if (ncomps < ordinate)
  			throw new IndexOutOfBoundsException();
  
  		int attributeIndex = m_description.getAttributeIndex(semantics);
  		if (attributeIndex < 0) {
  			addAttribute(semantics);
  			attributeIndex = m_description.getAttributeIndex(semantics);
  		}
  
  		if (m_attributes == null)
  			_setToDefault();
  
  		m_attributes[m_description._getPointAttributeOffset(attributeIndex)
  				+ ordinate] = value;
  	}