ok they said it couldn't be done..... (don't tell me that, it just fuel for my fire)..... i know this is not the dragon (it's a coco) - but with the HALT NMI disk controller they told me we could do NOTHING while loading.... BAHH YOU LOOSE !! lets play 7.8 Khz 2 voice music while loading a disk (yes...
OK. here is the complete sourcecode for my assembly demo + various utils for image/music conversion + a .dsk image of the demo in *normal* and autorun versions.... this demo has been timed for NTSC coco 1 or 2 32k (it will run on a d32 pal (timing is wrong)) - don't try it on a d64 as it will sound ...
lots of ways to perform a rotation... shearing is fast.... but this is faster... the *bad* thing here is the 2bpp limit, so we have to spend time looking up 4 pixels in a texture and combining those into one byte to plot essentially you just have a lookup that provides dx/dy for a given line through...
sin/cos lookup once per frame to calculate a deltax/y for a lookup into the texture LOTS AND LOTS (a months worth) of nasty tricks to improve speed.... sin/cos are 8:8 fixed point that vary from 1 to -1 (360 degrees transposed into 256 steps).... line start address table is 16bit pixel translation t...