Re: OpenGL orthographic projection

[Steve Baker <sjbaker1@airmail.net>]

Gregor Mückl wrote:

> Yes, GL_DEPTH_TEST is still turned on. Thanks for pointing that one out.
> However, I have only a limited set of fixed geometry with a distance from the 
> camera which is larger than that of the mouse cursor. Unless the contents of 
> the z buffer could change its meaning radically when switiching projection 
> matrix this should not be a problem.
The problem is that the contents DON'T change - but the MEANING applied to those
contents changes drastically.

> I understand that the z buffer layout 
> depends on the near and far clilpping plane distance in projection mode, so I 
> don't know how the graphics card will actually behave with respect to the z 
> buffer.
...and that is precisely the reason you need to disable the depth test whilst
rendering this kind of overlay stuff.  It's hard to figure out what's going to
happen - and you certainly wouldn't want to guarantee that nothing would go wrong.

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