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2004-10-26 06:24

Stingray
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Registered: Feb 2003
Posts: 117

FASTER 3D GRAPHICS

I've heard it said before that the way the VIC chip addresses memory (8x8 cells) makes it slower fo rendering graphics because of the extra calculations needed. So what way would you have had the Commodore engineers design an alternative addressing mode so that 3D graphics could be calculated quicker? I would realy appreciate your ideas on this.

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2004-10-27 09:16

Stingray
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Registered: Feb 2003
Posts: 117

at least none of the 10K would be wasted that way.

2004-10-27 10:29

Oswald

Registered: Apr 2002
Posts: 5086

wvl: you mean 40byte*256 do u ?:) or do u want a 256 color mode ? :)

2004-10-27 10:43

Stingray
Account closed

Registered: Feb 2003
Posts: 117

I'm pretty sure he meant 320 x 256 pixels, anyway I'm trying to keep this simple so there will be no 256 color mode at least at the moment anyway. It's taken considerable time to design the cct i've got and so far it's pretty basic. The more complex I make it the longer it will take for me design it.

2004-10-27 10:57

hollowman

Registered: Dec 2001
Posts: 474

only 16 colors, but one byte per pixel is fine with me

2004-10-27 11:37

Stingray
Account closed

Registered: Feb 2003
Posts: 117

1 byte per pixel would be 64k and my cct will only be addressing 16k like the VIC or are you thinking my cct should have it's own onboard RAM or something?

2004-10-27 11:39

Stingray
Account closed

Registered: Feb 2003
Posts: 117

I'ts a good idea and certainly would save some calculations.

2004-10-27 12:46

WVL

Registered: Mar 2002
Posts: 899

i mean 320x256 pixels :)

2004-10-27 20:31

MagerValp

Registered: Dec 2001
Posts: 1074

Yes, the C1 has a blitter.

2004-10-28 07:53

Stingray
Account closed

Registered: Feb 2003
Posts: 117

While trying to keep it simple, I have had an idea that should be easy to add to the design but not knowing much at all about 3d graphics I would like to know if it's worth including? My idea is to use either the V-blank area or the raster lines above and below the bitmap to move memory around while the graphics cct doesn't really have to be accessing memory anyway. To transfer 1 byte will take 2 clock cycles, 63 cycles per line minus 5 for refresh so thats 29 bytes per raster line. If I use just V-blank area (28 lines) it could transfer 812 bytes which would probably be reduced to 512 or 768 when put into my design. If I use all the raster lines above and below the image (minus the 4 lines I might need for ram access depending on the design) it could do 3132 bytes which would reduce down to 3072 (3k) when put into design. Using all the area above and below the display will give better results but may restrict me with some future enhancements I may whish to make to the circuit. This would actually be pretty simple to add to the design, I'm thinking a couple of addressable latches for writing the transfer pointers to (these are the bytes the programmer would write to), one latch for the cct to read to and write from (this holds the byte being transferred) and a n-bit ripple counter.

2004-10-28 09:13

WVL

Registered: Mar 2002
Posts: 899

instead of trying to make a blitter, you could rather add an option to have it clear memory. Clearing the gfx screen will CERTAINLY speed up 3d gfx a lot!