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Fast alpha blending for grass/foilage...

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I remember seeing a recent paper that talked about a new technique for alpha blending for trees/grass (I assume it would work for other things too). As I recall it was more than just simple alpha rejection, or blending with sorting, it was something 'new'.

Anyway, is anyone up on the latest alpha blending techniques? I want something that is fast and easy to implement. I dont mind if its 'fake' (compared to proper alpha blending with sorting), just so long as it looks 'good enough'.

Thanks

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Though I would like to have a peek if anyone figures out what paper you're referring to, I would highly recommend sticking with simple alpha rejection.

There's a pretty big performance difference between allowing transparency and simply allowing alpha pass/reject, especially with huge numbers of instanced objects like the kind you're talking about.

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Unless there have been some major advances in depth peeling techniques in the last year or so, that would be WAYYY too slow. I think the paper I was thinking of was this one...

http://www2.disney.co.uk/cms_res/blackrockstudio/pdf/Foliage_Rendering_in_Pure.pdf

Multipass alpha masks.. hmm anyone have experience implementing something like that?

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It looks like the link you showed was what you were looking for, but I thought I might share some alpha techniques with you.

Order Independent Transparency (Linked List):
http://developer.amd.com/samples/demos/pages/atiradeonhd5800seriesrealtimedemos.aspx
https://graphics.stanford.edu/wikis/cs448s-10/FrontPage?action=AttachFile&do=get&target=CS448s-10-11-oit.pdf

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@kloffy

Hmm thats a interesting idea (although most of the pictures were dead). So they are saying, draw everything once with alpha rejection, then AGAIN with alpha blending, and depth write off (to give you nice smooth 'fuz' around the rejected borders), eh?

@allingm

Interesting article, but I should have mentioned I am trying to stick with DX9 level solutions. Plus, since I am mostly concerned about distant foilage/trees, the final result doesnt have to be super accurate, I just need it to look 'good enough'.

[Edited by - ZealGamedev on September 2, 2010 12:59:01 PM]

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Quote:
Original post by ZealGamedev
Hmm thats a interesting idea (although most of the pictures were dead). So they are saying, draw everything once with alpha rejection, then AGAIN with alpha blending, and depth write off (to give you nice smooth 'fuz' around the rejected borders), eh?

Yes, that is how I understand it as well (the pictures work for me btw.). However, I haven't implemented it myself yet, but I'm planning on doing so in the near future.

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