gl_ztrick ?

[Baker]

Lately, I've been trying to understand the purpose of gl_ztrick.

As far as I can tell, DarkPlaces does not use this.

From planetquake.com/console

If this toggle is enabled the game will not clear the z-buffer between frames. This will result in increased performance but might cause problems for some display hardware.

Is gl_ztrick necessary in the modern world? Does make anything significantly faster?

Although I don't have any problems with it, I've read that some people have issues with it with, say, those Intel Integrated Media display adapters.

[Sajt]

It's about 10 years obsolete, I'd say. Depth clears aren't exactly expensive these days. QuakeWiki says TNT2 and newer cards should leave it off, and it comes as no surprise that a crusty old hack would be cut out of any decent modified Quake engine.

[Baker]

Cool

Of the video card problems I've seen and heard about, gl_ztrick is the source of many of them. Especially since it defaults to 1.

I've read about this causing problems in Qrack and ezQuake with some video cards.

/Noticed FitzQuake has gl_ztrick removed as well.

[Spike]

modern graphics cards feature optimisations which only work with ztrick disabled, as well as faster buffer clears.
This means that you'll get one to three percent better framerates with ztrick disabled. Coupled with the driver issues, all modern engines should at least default to it being off.

Its a funky trick though, and can be found in a large number of early GL applications... At least quake based ones!

[mh]

Agreed, there's no need to keep it at all. Removing it will also give you a higher precision depth buffer.