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Non-API (software) Texture Mapping - Perpsective correctness question


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Posted 04 December 1999 - 10:15 AM

I am programming a software rendering app that I just added Texture Mapping to. Anyway, one thing I noticed is that as my planes that are being textured begin rotating such that perspective begins to come into play, my textures seem to "slide" along the intersecting edges. I know why this is, after a full night of internet research, and now I come to the harder problem of fixing it. I know some buzz words like anisotropic filtering, etc., but I am mostly wondering if there is a good site or if there is someone here who has a great idea for me. I'd be happy to paste some code snippets or take this to email if you like. Thanks.

Andy Luedke


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Posted 02 December 1999 - 09:25 AM

I am beginning to sound like a broken record but anyway: Check out Michael Abrash' Black Book of Graphics Programming - it explains (with source) perspective correct texture mapping + a lot of other neat stuff.

/Niels


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Posted 02 December 1999 - 01:18 PM

Ok. I have the black book, and Pooh Bear and the spacestation is a great read, but when I implement it (I don't like to borrow his source) it doesn't prove to be perspective correct. He says it is, and gives a pretty vague reason why, but it really isn't. The real problem arises when I try to determine that certain pixels should be closer (from the texture) as the z values increase. I know that the method in the black book is not perspective correct from my research into this. Anyway, thanks for the recommendation, and I'm still hoping for more.

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Posted 04 December 1999 - 12:20 AM

I just checked the book - he actually specifically says that "perspective texture mapping is a complex subject that's outside the scope of this book". My mistake, sorry 'bout that!

/Niels



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Posted 04 December 1999 - 08:47 AM

I have the book and another limitation I've found of his engine XSharp, is that there's no support for transformation from world coordinates to the view coordinate system. He just assumes that the viewer is looking down the z-axis. Maybe that's a reason the engine is so fast (no extra transformation and no matrix inversions).

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Posted 04 December 1999 - 10:15 AM

Could it be that your problem is from interpolating at a 'n' pixels too high?




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