vertex_format_end();
Returns: Real
This function must be called after defining any new vertex
format. It returns the new format "handle" (index) which must be
used in all further vertex functions that refer to this new
format.
vertex_format_begin();
vertex_format_add_colour();
vertex_format_add_position();
my_format = vertex_format_end();
The above code will create a new vertex format with just colour and position values and then store the format id in the variable "my_format".