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jPCT-AE - a 3d engine for Android => Support => Topic started by: kiffa on November 30, 2013, 08:35:06 am

Title: Does mobile GPU(s) support the Early-Z culling?
Post by: kiffa on November 30, 2013, 08:35:06 am

And another question:

PowerVR SGX uses TBDR, so sorting objs front-to-back makes no sense on such device.

But for Tegra(IMR)、Adreno(TBR)、Mali(TBR), will "Config.stateOrientedSorting = false" gain better performace?

Title: Re: Does mobile GPU(s) support the Early-Z culling?
Post by: EgonOlsen on November 30, 2013, 05:17:44 pm

State changes are usually more expensive than a few zbuffer checks and some overdraw. You can give it a try if you think that it might help in a particular scene, but to be honest, i wouldn't bother with it.

Title: Re: Does mobile GPU(s) support the Early-Z culling?
Post by: kiffa on December 03, 2013, 09:32:48 am

Thanks.

You mentioned state changes are usually more expensive than some overdraw. I want to know how to quantificat the cost of different behavior (then could compare them in order to do the trade-off). For example, per shader state change will cost XX ms(ns) average, or shader state change is xx times cost than texture state change...

Any information(tools、article、experience) will be thankful.

Title: Re: Does mobile GPU(s) support the Early-Z culling?
Post by: EgonOlsen on December 03, 2013, 11:28:24 pm

I think the only way it to try it. What costs how much depends on the platform, on the scene and on the gpu and it's drivers. It's almost impossible to give proper numbers for this.