[Coco] Impossibly-fast CoCo 3 sprites :)

[Mark McDougall]

Roger Taylor wrote:

> Each sprite gets it's own subroutine that uses direct values 
> written to the screen with indexed addressing.  

So where do you think the main speed increase comes from? The "loop 
unrolling", skipped transparent pixels, or faster opcodes (addressing modes etc)

Interesting because on the SI Model 4P port, the 4P graphics hardware is 
quite slow, and IIRC I unrolled the "sprite" routines (by hand) to gain a 
reasonable amount of speed, but nothing like 8x I don't think (not that I 
profiled the difference).

You realise that you're also one step closer to the dynamic recompilation 
techniques used in MAME and various other emulators!?! ;) Of course in your 
case you're 'compiling' graphics primitives rather than CPU code from 
another processor... but still...

Regards,

-- 
|              Mark McDougall                | "Electrical Engineers do it
|  <http://members.iinet.net.au/~msmcdoug>   |   with less resistance!"