Re: Dramatic improvement of depth buffer quality

[Felix <fx...@gm...>]

Am Sa, den 01.01.2005 schrieb Roland Scheidegger um 19:00:
> Felix K=FChling wrote:
[snip]
> I'm a bit sceptical that this really improves depth buffer quality in=20
> general. With D3D it is (if the hw supports it) possible to use a w=20
> buffer instead of a z buffer, which has the same precision for far and=20
> near objects. However, the loss of precision for near objects was often=20
> considered unacceptable. (Radeon R100 and R200 support this, but R300=20
> and up no longer do, or at least the driver doesn't expose it, so it=20
> looks like it wasn't that useful after all, and not many applications=20
> afaik requested w buffers).

[... following up to my other reply ...]

Another problem with W buffers is that linear depth interpolation
doesn't give the correct results with intersecting surfaces. This is
only achieved by the perspective division which is not applied to W (in
fact the perspective division divides x, y and z by W). This makes
W-buffers unsuitable for OpenGL. But this is not what I am proposing,
just in case I was misunderstood. Reversing the depth range and using
floating point numbers just changes the encoding of depth values in the
depth buffer, it does not change the semantics, like a W-buffer would
do.

>=20
> Roland
--=20
| Felix K=FChling <fx...@gm...>                     http://fxk.de.vu |
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