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Ward Reflection Model

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jollyjeffers

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So I think I've cracked the Ward reflection model. Thanks to a kick in the right direction from Simon I managed to get myself unstuck. He suggested implementing it entirely in world-space at the vertex level, which worked pretty much first time. Thus with that as a reference I moved it piece-by-piece into the pixel shader.

Despite my assertions I was muddling up a couple of the coordinate spaces - my core VS was fine, but I hacked in a couple of extra lines at the last minute and forgot to transform them correctly [embarassed]



The ward model is an anisotropic one, thus you can effectively change the shape of the specular highlight my messing with the parameters. I've forgotten to annotate the above image, but the columns and rows are 0.0 to 1.0 in 0.2 steps - with the top-left being the 0.0,0.0 origin.

I'm not entirely convinced its correct, but I never seem to be happy. At least it's not broken - so if I have time later on I can always come back to it.

A few of my resources make mentions of the Ward parameters being quite sensitive, and that values less than or around 0.2 work best - which would correspond with the results I have above.

The idea, given its an anisotropic model, that I can represent various metalic and similar manufactured surfaces:



Reckon I could pass that off as brushed metal?
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I'm convinced. [grin] Maybe it it was a bit brighter (add an environment map..?)

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Looks a bit odd actually, esp. the way it curves up around the sphere. Perhaps if you put this model on those biohazard models I'd be a bit more convinced due to the fact that I'd be more familiar with how that reflection/geometry combination works in real life. (i.e. I've never seen metallic surfaces in a sphere, but I've seen a ton that are cylindrical)

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Since that shot I've had a brighter one courtesy of some additional ambient lighting, so thats okay. I don't think an environment map will be possible - I'm fillrate bound as it stands, adding extra pixel effects is just going to make my GPU catch fire [lol]

Heh, a brushed metal cylinder was my next task [grin]

Problem is I suck at modelling, even the simple stuff - and I found that Wings3D was doing some really odd things with triangle-orderings. So not sure I like using it to create models anymore [headshake]

Cheers,
Jack

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Who said you have to make a new model? Do those old barrels that you had not work anymore or something?

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I'm trying to move away from those barrels - this is for a serious academic project (or something like that) and I don't think they'd appreciate such gimmicks [rolleyes]

I've almost got a barrel sorted now, so all's okay...

Cheers,
Jack

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