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Old 19 June 2016, 14:38   #1
mekhall
 
Posts: n/a
Question Blitter fill problem

Hi all,

I have decided to do now what I was not able to in the beginning of 90:ies when I first tried out Amiga assembler - do some sort of simple demo.

For this I'm starting out with the "classic" rotating 3d graphics.

Right now I'm having some problems with the blitter area fill. I am drawing my lines with the one-dot bit set, I'm drawing them from top to bottom and I'm blitting the first pixel of the line Elsewhere. I thought that was all that was needed to get the polygon ripe for filling.

I fill after calculating a bounding box, and I fill in descending mode.

What happens is that sometimes I get horizontal lines. This is because for some line lengths and angles there is only one pixel per scanline. I guess the last pixel of the line coincides with the same pixel of the line it connects to.

I've tried to illustrate the problem in the images I'm attaching to this post.

So, what is the best way to deal with this? (I guess this is a common newbie problem)
Attached Thumbnails
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