FreeLists / openbeos / [openbeos] Re: The Scientific Method aka BresenhamNewsletter Article

["Martin Krastev" <blue@xxxxxxxxx>]

"Alexander G. M. Smith" <agmsmith@xxxxxxxxxx> wrote:
> That sort of rounding problem shows up as gaps between polygons in 3D 
> systems, since the
> edges are usually placed using a line drawing algorithm.  You want the line 
> to be exactly the same,
> no matter what the order of the endpoints is.  It's a bit trickier since the 
> vertices are floating point
> numbers until the very last transformation step.  Takes a lot of care to get 
> it "pixel perfect".

it does take a lot of care indeed. just as a sidenote in this regard, if you 
care about sub-pixel
precision then your vertices would remain fp (or fixed-point, whatever you use) 
even past the
last transformation (i assume you mean the NDC-to-window transform), until the 
very last
moment of putting your pixels on the screen.

Michael Phipps <mphipps1@xxxxxxxxxxxxxxxx> wrote:

> Yikes. I bet that would be no fun to debug down the road. :-/

as with any task which requires sound math, doing your numerical analysis in 
advance
and with good care is essential. what differentiates computer graphics from the 
rest
computational areas of intense math, though, is that your errors usually pop up 
right
in your face ;)) you just need to have the eye for those.

-blu