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Hey all,
In trying to implement a LDraw renderer I've been scouring the web looking
for raster-painting algorithms. While I've found plenty of line-drawing
algorithms (the Bresenham seems to be pretty nice) I haven't found squat for
drawing a filled triangle or quad.
I've pretty much figured out how to draw a triangle in 2d based on the
Bresenham line-drawing algorithm, but I'm frankly stumped when it comes to
the z-buffer. What I *do* have is absolutely riddled with floating-point
divides, and doesn't quite work anyway (having incorrectly determined the
z-slope of the triangle in order to determine the z-depth at an arbitrary
point).
Does anyone have an algorithm they'd be willing to share?
Alternatively, is there a specific keyword I should search for that would
help me find what I need in Google or AltaVista?
Cheers,
- jsproat
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Message has 4 Replies:
 | | Re: Drawing triangles in a Z buffer
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| Here is one starting point: (URL) of free information, there is at least one quick-and-dirty FAQ under there written by an excited child. You're looking for something about triangle or scan line rasterization with z-buffer. I assume you've done (...) (23 years ago, 13-Feb-02, to lugnet.cad.dev, lugnet.off-topic.geek)
| | | Re: Drawing triangles in a Z buffer
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| (...) I may be missing your point/problem but... Think you may need to go bi-linear in your Z calcs. Yes this makes a Suppos'dly one pixel lookup method a two+ per pixel but if you are already using a scan line method you have the precalculated (...) (23 years ago, 13-Feb-02, to lugnet.cad.dev, lugnet.off-topic.geek)
| | | Re: Drawing triangles in a Z buffer
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| (...) If you don't mind C code, there's the zAddTriangle() function in stub.c in the ldlite or ldglite source code. The old 1.6 ldlite source is a bit easier to follow since it doesn't have all the extra shaders. Also, it's a linear z-buffer, which (...) (23 years ago, 13-Feb-02, to lugnet.cad.dev, lugnet.off-topic.geek)
| | | Re: Drawing triangles in a Z buffer
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| "Sproaticus" <jsproat@io.com> skrev i meddelandet news:GrGFrK.9nJ@lugnet.com... (...) There must surely be one (or more) in Graphical Gems (URL) (if that URL still is valid, otherwise search for Graphical Gems) a bit dated, c code, but useful. -- (...) (23 years ago, 13-Feb-02, to lugnet.cad.dev, lugnet.off-topic.geek)
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