[Bf-committers] Normalise patch - don't apply it
Nathan Vegdahl
cessen at cessen.com
Thu Feb 9 18:55:09 CET 2006
Yeah, that makes sense. Okay, I agree, we shouldn't use my patch.
(Jump forward about ten minutes...)
I just did some tests to verify previous results of mine, and they
weren't verified. So, yeah, I have no problem at all with leaving the
code as-is now. For those who are curious, here's the thing that
happened to motivate my changing it in the first place:
--------
Anyway, aside from that there's still something odd going on.
Take a look at these debug renders:
http://www.cessen.com/storage/temp/debug_render_2.png
http://www.cessen.com/storage/temp/debug_render_2_fixed.png
Both renders are simply blasting out bump-mapped normals to the RGB
channels (i.e. X->R, Y->G, Z->B). In both cases the Normalise function
was the last thing done to the vectors before they were blasted.
The first one uses the existing code, the second one uses my
so-called "fix".
Regardless of the source of these vectors, with the existing code
they should have either been valid normals (nice clean RGB values) or
they should have been null vectors (solid black). Instead we have
patches of noise outlined by distorted normals.
And remember, the only difference between the two images is the
"fix" to the Normalise function.
--------
I guess it was just a fluke, because I can't seem to reproduce it.
I swear the only thing I changed was the Normalise function. But it's
working now... so, yeah. Let's leave it as is. Sorry for all the ruckus.
--Nathan "Cessen" Vegdahl
Michael Reimpell wrote:
>>It was setting
>>super-small vectors to <0,0,0>, which really isn't a good behavior for
>>something that's supposed to return vectors of length 1.
>
>
> The normalise function is _not_ supposed to return a vector of unit length for
> the zero element of the vector space! Mapping 0 to 0 is the most reasonable
> mapping. Translation, e.g., 0 -> (0,0,1), has nothing to do with
> normalisation! Of course this applies to all floating point representations
> of the zero element, i.e., all vectors of length below a certain threshold.
>
> Regards,
> Michael
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