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In lugnet.cad.dev, Jeremy H. Sproat writes:
> 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?
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 is a bit easier to use in some cases, but
tends to allow more bleed through (z-fighting).
Have fun,
Don
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Message is in Reply To:
 | | Drawing triangles in a Z buffer
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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 (...) (23 years ago, 13-Feb-02, to lugnet.cad.dev, lugnet.off-topic.geek)
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