Posted by elect on Mar 03, 2016; 11:41am
URL: https://forum.jogamp.org/Why-is-the-z-value-read-from-glReadPixels-always-1-0-tp4036395p4036417.html

Irene Tang wrote

I think the reason might be that nothing ever rendered in the clicking point, so the z-depth would be the default 1.0.

Well, then yes, it is like this. What you read is the default clear value for the depth buffer