From: Christopher Phillips (
Date: 2004-10-31 14:35:26

On 31 Oct 2004, at 18:45, Hatch wrote:

>   Now that I have almost finished the semester I would like to look at 
> interfacing my cct to the C64,

Uh-oh, here comes another C-1 ;-) ;-)

> One thing I would like to do when I redesign the cct is to give it a 
> way to address graphics data so that 3D graphics can be calculated 
> quicker (basically something other the 8x8 cells) either 200 rows of 
> 40 bytes (horizontally formatted) or 40 columns of 200 bytes 
> (vertically formatted).  This way my cct will be useful for something. 
>  At the Moment I'm leaning towards horizontal formatting (but it's a 
> question of which ever way is faster for calculating 3D graphics 
> with).

For plotting 3d graphics in software on 6502, I'd lean towards vertical 
formatting - that way you can do a single routine for xor-filling 
across a line, which you can index your stores in order to select the 
pixel row you are writing to. That's assuming you're using c64 memory.

OTOH, if you use external memory and have a c64 mapped IO register that 
writes to an auto-incrementing location in VRAM, then horizontal 
ordering would be better.

Of course, you could get better performance if your hardware did some 
of the 3d work itself, but that's a much harder problem :)

Good luck!

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