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Next-Generation Graphics Engine
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 Post subject: edge shading
PostPosted: 23.04.2008, 16:15 
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Joined: 15.04.2008, 00:33
Posts: 15
Edges seem to be the neglected geometry in modern graphics. I will be walking along with the fantastic illusion of depth and texture provided by normal-mapped-depth-mapped-parallax-occlusion-dynamically-shadowed-specular-mapped surface only for it to end with an abrupt straight line which makes it feel like a cardboard-cutout.

I have been thinking about how one can play with the edges of triangles while having the minimum impact on the standard pipeline. I want to make triangles not quite triangular without having a disproportionate impact on, for example, occlusion culling.

Possible applications:
(> edge textures
(> procedural edges
(> allowing parallax-mapped bumps to stick-out (or in) at the edges

Anyone have any ideas? Discuss.


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 Post subject: Re: edge shading
PostPosted: 23.04.2008, 17:37 
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Joined: 19.11.2007, 19:35
Posts: 218
They're not entirely neglected. Its just an issue of what's of greater worth. Geometry shaders in DX and the relevant OGL extensions make it easier to make fins. GPU Gems 3, "Next Generation Speedtree Rendering" has a chunk devoted to using fins and displacement maps to add irregular silhouettes to their trees. Probably would be a good article to dig up.

Discarding the fragment could "cut" into geometry without using fins though. I suppose something like a grayscale SSS density map could be used to represent the frequency at which a pixel will be cut as the dot-product of a normal map (post adjustment against the surface the normal) and the view vector approaches 1.0f. The geometry of the object would be an issue though, don't want to cut holes into the center of it because something is sticking out there.

This can also give you some ideas:
http://citeseer.ist.psu.edu/menezesdeoliveiranet00relief.html


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 Post subject: Re: edge shading
PostPosted: 23.04.2008, 18:07 
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Joined: 15.04.2008, 00:33
Posts: 15
Thanks, I'll look at both of those.


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 Post subject: Re: edge shading
PostPosted: 27.04.2008, 17:18 
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Joined: 19.11.2007, 19:35
Posts: 218
Whoops, that should be as the dot product approaches 0.0f and not 1.0f (that would be head-on).


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