English Amiga Board - View Single Post

deimos · 09 October 2019, 08:30

Thanks,

My initial tests with

Code:

UWORD minterm = (colour & 1 << i) ? 0xfa : 0x2a;

and bltbdat set to a random constant (for testing) appear to work in that I get different coloured lines and no garbage.

I'll also slap some different background colours in as a complete test, just because it's easy.

One last line draw related question... back in '89 or so I was trying to blit lines onto interleaved bitmaps but struggled with the occasional line being wrong, there would be odd pixels of the wrong colour as if Bresenham had decided to go up or down one pixel earlier or later for some bitplanes.

I'm going to try and change my code to use interleaved bitmaps because it makes sense for other things, but can you think of any reason why line blitting won't work on what are essentially very wide bitplanes, which just the modulos changes to reflect this?

09 October 2019, 08:30	#14
deimos It's coming back! Join Date: Jul 2018 Location: comp.sys.amiga Posts: 762	Thanks, My initial tests with Code: UWORD minterm = (colour & 1 << i) ? 0xfa : 0x2a; and bltbdat set to a random constant (for testing) appear to work in that I get different coloured lines and no garbage. I'll also slap some different background colours in as a complete test, just because it's easy. One last line draw related question... back in '89 or so I was trying to blit lines onto interleaved bitmaps but struggled with the occasional line being wrong, there would be odd pixels of the wrong colour as if Bresenham had decided to go up or down one pixel earlier or later for some bitplanes. I'm going to try and change my code to use interleaved bitmaps because it makes sense for other things, but can you think of any reason why line blitting won't work on what are essentially very wide bitplanes, which just the modulos changes to reflect this?