Re: z88dk SP1 software sprite library
Posted: Fri Dec 29, 2017 3:54 pm
I think the stack pointer is important as SP1 uses dynamic memory. The source for the Blackstar example has the following comment in it's zpragma.inc:
Digging into the include file sp1.h, SP1_DRAW_LOAD and so on appear to be function pointers:
So it looks like when you call sp1_AddColSpr you specify a drawing method in the parameters. Don't know if this makes it any clearer? 
I've found that poorly updated documentation is the curse of the z88dk. Your best bet would be to get into contact with Alvin as he is the font of all z88dk knowledge - or even better, somehow get him to register on this forum. I think he's busy with development on the ZX Spectrum Next these days but I've learnt more about using the z88dk in forum posts with him than I have from anywhere else.
I'm using R-Tape's posted beginners sprite code to write myself a basic sprite handling routine from C that I can understand.
Code: Select all
#pragma output REGISTER_SP = 0xd000 // typical stack location when using sp1
Code: Select all
extern void SP1_DRAW_LOAD1(void); // load sprite 1-byte definition graph only no mask; sw rotation will use LOAD1_NR if no rotation necessary
extern void SP1_DRAW_LOAD1NR(void); // load sprite 1-byte definition graph only no mask; no rotation applied, always drawn at exact tile boundary
extern void SP1_DRAW_LOAD1LB(void); // load sprite 1-byte definition graph only no mask; sw rotation as LOAD1 but for left boundary of sprite only
extern void SP1_DRAW_LOAD1RB(void); // load sprite 1-byte definition graph only no mask; sw rotation as LOAD1 but for right boundary of sprite only
I'm using R-Tape's posted beginners sprite code to write myself a basic sprite handling routine from C that I can understand.