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Overdraw, how does it work and how bad is it?
I've been trying to understand this so that I can optimize models with transparent portions as best as possible and I'm having a hard time finding info. Where exactly is the drain from overdraw issues? The name "overdraw" would seem to imply that the more transparent space that is rendered on screen, the worse it is, if… -
Re: Overdraw, how does it work and how bad is it?
From my experience I have always gone with B. More geo yes but less area to render out in alpha = less overdraw. I try to keep my meshes as 2 pieces. trunk and leaves. Not sure if this is a big performance hit but it's the way I've done it and it's always worked. I remember GDC a few years back when the guys from Crytek… -
Re: Overdraw, how does it work and how bad is it?
In general B should be the best, although if the tris are far away enough so that A would appear at about 4x4 pixels or less on screen than A will probably be faster. for question 2 I think if you have a lot of overlapping geometry then B would be faster than C because the renderer will check the if the pixel is occluded… -
Re: Overdraw, how does it work and how bad is it?
Sorry for necro'd this thread, just want to be sure about one thing regarding overdraw. As far as I know if in example B transparent shader/material is used then every texel in this geo is considered transparent. Even if alpha of that texel is 0 (when it looks opaque). If alpha masking is used then only texels with alpha… -
Re: Overdraw, how does it work and how bad is it?
I'm working on the particles for a racing game at the moment, and that includes other enviro effects like a tornado and storms. The large particles aren't as bad as you'd think - it's better to have 100 large planes make up a tornado (and this is a HUGE tornado, seen from EVERY angle) than hundreds of smaller ones, simply… -
Re: Overdraw, how does it work and how bad is it?
1) As far as I know, B is the better option because it is only the pixels that are marked as transparent that cause the problems. In general its easier for an engine to render a few more tris than it is to process giant transparent areas, so trimming down those places is pretty key. Espseically when you have several… -
Re: Overdraw, how does it work and how bad is it?
Most modern engines are based on some kind of deferred shading/lighting. This has the benefit, that all these engines could handle lot of geometry, lights and post processing effects. One of the major drawbacks is, that you can't handle transparency at all or only very clumpsy. The most often used solution to this kind of… -
Re: Overdraw, how does it work and how bad is it?
at any time you must decide what will be better for given situation.. general rule should be: be wise with anything you do and if in doubt do compare test ;) truth will be revealed to you/// -
Re: Overdraw, how does it work and how bad is it?
Yeah that's almost right - 1-bit alpha also causes overdraw on every pixel, even the opaque ones. With 8-bit alpha opaque pixels are just as expensive as partially transparent pixels. When it gets expensive, is when you have several layers of alpha cards on top of each other - because with opaque pixels, the render does… -
Re: Overdraw, how does it work and how bad is it?
Crydev Wiki: ~Use alpha textures, but don't go overboard. The more the space on screen covered by an alpha plane, the more expensive it will be to render. Alpha planes use alpha testing, and thus, require a second drawcall. ~Keep the overdraw in mind. It is often better to cut the alpha-mapped polygon plane to match the…
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