Spectrum Computing

yeah, if you're doing a custom engine for your game, chasing the ray is ok. but with a general-purpose engine, which intended to be used by people who know little to nothing about such arcane tricks… remember, it is 1986 now in this topic! ;-) and i am not writing something for Joffa to use. ;-)

ah. i see it more like a "hardware sprite", though: you change the coordinates, and the sprite immediately (well, almost) moves to the new place. that's all you need to do — just tell the engine the new coords and gfx address. it is harder to program (the engine itself, i mean), but much e...

Can't you use a callback function or something for end of game logic/start preparing next frame? this will limit the ways to use the system. the idea is that you can move the sprites anywhere in your code, when you want it, not when the system wants you to do it. you command — the system obeys, not...

Defo do the sort at the end of the frame though ready for the next frame, don't attempt to sort whilst drawing. sadly, this is something i cannot afford. i don't want the user to call any "LETS-END-THIS-FRAME" routine manually, so i have to sort everything right before i draw it. and &quo...

I think LISP is probably better as a "programmers" language than Forth they aren't that different, actually. both basically provide a "raw" low-level access to some imaginary virtual machine, and you can build your code upon that. Forth is simplier, though, and easier to impleme...

I think Jetpack (and other Ultimate games) erase and draw sprite at the same time, line by line. It sounds like horrible idea but sprites usually move just a little bit so this method basically replaces flickering by possible tearing. Well, you can check how it looks on YT yourself. with Jetpack th...

by the way, my first contant with Forth was on ZX. i had… yeah, Abersoft Forth, pirated of course, without any documentation. and i had no idea what that "Forth" was. it was on a cassete with other languages (LISP, HiSoft Pascal, etc.), so it was definitely some language, but… what to type...

ParadigmShifter , the problem is that i want to make everything easy to use. the idea is that you only call "SPR-UPDATE" word with new sprite position and animation frame, and the system will magically do the rest. i don't want the user to think about interrupts, where to insert HALT, and...

also, moving the system to $8000, and removing RAM-DISC will leave about 12KB of RAM free for user code. this is quite a lot (the whole system is ~15KB now, or ~18KB with fullscreen editor). so i will prolly ditch RAM-DISC at all, and implement support for TR-DOS and +3DOS instead. i mean, 'cmon, yo...

i implemented "prepare, then redraw in interrupt handler" engine for 16x16 sprites with run-time shifting… and will throw it away now. ;-) it doesn't worth the efforts. it requires 2KB for buffers, takes a lot of time to prepare buffers, and dog slow even with 13 sprites (this is as much a...

There's always Machine Lightning, which presumably has similar capabilities. While the software is in the archives, the documentation appears to be lost at the moment :cry: thank you! but it still doesn't have a source code (or i am unable to extract it). i mostly need the source to create relocata...

you doesn't switch banks , you are changing address mapping . think of it this way: address $C000 can be mapped to one of several memory banks, and you are selecting to which one. there is no changes in bank order. i.e. $C000 is a "window" you are using to look at a huge RAM, and by OUTing...

oh, i see. Jonathan did exactly what i thought of: simultaneous erasing and drawing after vblank. only AGD doesn't have run-time sprite shifting, so no need for any temp buffers. ok, i will prolly make two versions: with shifts, and without. so 3 sprite engines now, lol: White Lightning like, XOR16 ...

creating flicker-free XOR sprites is surprisingly hard. i wonder how Jonathan Cauldwell did it in AGD. althrough AGD is not shifting sprites, i believe. i created 16x16 blitter with shifting, so i can blit at any x pixel coord, but of course it flickers hard. HALT only helps with 2 sprites or so. an...

added (optional) OR/XOR/AND blitters too. with all blitters included library size is ~1KB.

wrote simple sprite blitter. currently only in overwrite mode, at char positions. tested on White Lightning sprites, lol. the code is not superfast (althroug it is using unrolled LDI loop per sprite line). it would be easy to modify the blitter to allow arbitrary y coords (not restricted to chars), ...

i cached "NEXT" in IX. the code became slightly smaller, and slightly faster. not much, but why not? IX was used for user area pointer, but we don't have a lot of uservars anyway, so it was a waste of register. i wonder if caching TOS in DE will do any good. but this will require rewriting...

Can I try the editor somewhere and is there a documentation ? I wonder how much space a minimal fullscreen editor would take. 2.9 KB is quite a lot, considering line editor can take perhaps one third of space, I guess. latest demos in this topic are compiled with the editor. just type "LOADT 1...

by the way, contented memory sux! Erathosthenes test is ~1.7 seconds faster when the system is uncontended.

but i am not ready to waste 8KB of RAM by moving the system to $8000 yet.

Will this ever be available to use on real speccy or are you concentrating on emulator only? it should work on the real hw, why not. i don't have real machine anymore, though, so any bug reports from reals are welcome! The floating point is a nice useful feature and would say a full doubles extensi...

i really want "ex sp, sp'" instruction. having two stack pointers and 4ts (ok, even 8ts) way to switch between them is something any Forth programmer always deaming of! ;-) (unless we can use any register as stack pointer, of course.)

funny, that's exactly how they are defined:

flange , thank you for your support! yep, "advanced" comparisons are not properly tested yet, thank you. they weren't in the original, and i wrote the code in "blind mode", just to have something there. ;-) as for not popular language… i am using x86 Forth system on daily basis ...

by the way. WIP version to play with: download .TAPs . WARNING! this is NOT final! it should work, but there may (and will) be some bugs. there are 3 .TAP versions, all with demo game. WARNING! demo game works only in 32cols mode. to load demo game, use: "LOADT 1 LOAD" source code will be ...

also, there will be a target cross-compiler which creates "turnkey" apps, omiting all headers, and all unused words. but you'll need x86 GNU/Linux to use it.