Posted by elect on Feb 25, 2016; 7:50am
URL: https://forum.jogamp.org/SOLVED-mouse-input-tp3504609p4036339.html

OpenGL is about space transformations, this makes things *relatively* easier.

http://web.archive.org/web/20140106105946/http://www.arcsynthesis.org/gltut/Positioning/TransformPipeline.svg

when you draw the rectangle you are in window space and what you want to do is retrieving the world space coordinates (I guess). Then you have to apply the inverse transformation, this is usually called unproject

There should be a lot of references on the net

Irene Tang wrote

This looks right, you go from object (model) space to window space.

For example, if model matrix is the matrix that transforms from model to world space, the inverse, model^(-1), transforms from worlds to model space.