How to transfer the zbuff values got from the select mode before using gluUnproject?


I use the standard method “selecting - hit record” to identify the object user hits. My problem is then how to deal with the z-buffer values in the select buffer beforing using the function gluUnproject(). The z-buffer values are ones before the model transformation, but gluUnproject() requires the z buffer value after the model transformation.

You may ask why I have to use gluUnproject () to get the coordinates. How come I don’t use the names in the buffer? My need is that I have a sketch plane in a 3-D space and I have to decide the location in the plane where the user hits. Please advise.