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Subject: 
Re: White noise around model with colored background
Newsgroups: 
lugnet.cad
Date: 
Wed, 10 Oct 2007 16:32:17 GMT
Viewed: 
2844 times
  
In lugnet.cad, Don Heyse wrote:
   In lugnet.cad, Travis Cobbs wrote:
   In lugnet.cad, Travis Cobbs wrote:
   to this. After spending a few hours getting nice alpha data into the image file for transparent parts, I realized that the same set of steps would probably work for the edge lines. So, I gave it a try, and sure enough, it worked. See here:

http://www.halibut.com/~tcobbs/ldraw/private/AAAlphaDemo.html

But I was wondering about the first set of images. Did you get this with only the 3 pass method you described, or did you also have some form of FSAA enabled? If you got it without FSAA, that’s really impressive.

The image on the above page was rendered with antialiased lines, but no FSAA. FSAA would have brought the halo back, since there’s no way to have FSAA on part of the scene, but not on other parts. In theory I could render the image twice, once with FSAA, and once without. I could then use the FSAA version for all fully opaque pixels and the non-FSAA version for all partially opaque pixels.

  
I was also wondering if FSAA does anything to the stippled transparency. I don’t have the hardware so I can’t try it, but I’m sorta partial to the way the cheesy stippled transparency comes out when you antialias it. At least for instructions, I think it’s a bit less confusing.

On my ATI card at work, the stipple pattern doesn’t get antialiased. Of course, if the stippling is implement via some sort of alpha texture tricks, this would make sense. (Just do a Google search for MSAA alpha textures.) My ATI card doesn’t support “transparency antialiasing”, which is a feature on newer cards to antialias alpha textures. I don’t think my nVidia card at home supports transparency antialiasing either, but nVidia might not use texture tricks for their stipple support. And even if they do, LDView goes up to 16x FSAA there, and as far as I know 16x FSAA isn’t fully MSAA. (Oddly enough, nVidia’s marketing department claims that my card maxes out at 8x FSAA, and yet the card happily allows 16x FSAA in OpenGL.)

In any event, you could get the same effect with blended transparency by drawing transparent polygons from front to back with depth testing enabled. The polygon sort algorithm might have to be more accurate than mine to avoid artifacts, though.

--Travis



Message has 1 Reply:
  Re: White noise around model with colored background
 
(...) Wow, those lines are much smoother than anything I remember getting with simple antialiased lines. Was that rendered by ATI or Nvidia, or do they both give you results like that? Does the SMOOTH HINT make a big difference? I think I set it to (...) (17 years ago, 10-Oct-07, to lugnet.cad, FTX)

Message is in Reply To:
  Re: White noise around model with colored background
 
(...) Hey those look nice. Just for kicks I ran off a test with the ancient method of ldglite at 2x scale followed by ImageMagick mogrify 50% to shrink it back and antialias. (URL) I like your edge outer edges better. Very nice. I'll have to look (...) (17 years ago, 10-Oct-07, to lugnet.cad, FTX)

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