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Demos Amiga Demoscene Archive Forum / Coding / Planar Pixel Plotting
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#1 - Posted: 5 Jan 2010 01:55
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Hardcode not hardcore. Well, it is hardcore after all...
#2 - Posted: 7 Jan 2010 01:08
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happy hardcore ravers in the house ...put your hands in the air and blow your whistles!!
#3 - Posted: 23 Feb 2010 04:15 - Edited
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By extending your bitplanes to f.ex 64 bytes wide for faster addressing you can do:

Little bit puzzled what this means in real life use.
Many many thanks to Kalms,d0DgE and rest for great tips so far.
#4 - Posted: 23 Feb 2010 05:16
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It just means there's a 64 byte span between one bitplane line and the next, and so you can address individual lines very fast by using a single shift instruction to multiply the Y coordinate by 64.

For a typical lowres screen you would have 64*256 bytes per bitplane and set data fetch registers as usual, but set the bitplane modulos to 24 so it reads the usual 40 bytes and then skips over the last 24 to get to the next line.

Those extra bytes between the lines are not lost or anything, they are fully useable like any other chipmem, just in a poor arrangement.
#5 - Posted: 23 Feb 2010 14:30
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Actually, I will adjust my introsystem to such aligned bitplanes.
To only have to do an "lsr.w #6,dx" to determine the Y coordinate speeds up the pixel drawing

But ATM I'll stick to standard 40-byte aligned planes b/c it would be too much of a work to change my framework by now.
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A.D.A. Amiga Demoscene Archive, Version 3.0