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Port of STNICCC-2000 for the BBC Micro.

Home Page: https://bitshifters.github.io/posts/prods/bs-beeb-niccc.html

License: MIT License

Python 41.21% Batchfile 0.51% Assembly 56.35% Makefile 1.26% VBA 0.67%

bbcmicro demo demoscene revision2020 bbc stniccc

stnicc-beeb's Introduction

beeb-niccc

Recreation of STNICCC-2000 demo for the BBC Micro.

Released at the Revision 2020 demoparty winning 1st place in the Old Skool Demo compo.

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stnicc-beeb's Issues

Include low, medium and high quality exes on the disc?

Outro doesn't work on Model B.

Timing is too tight and specific to Master.

Credits?

We'll want credits at the end for the folks involved.
Plus thanks / greets as ever.

Auto-detect sideways RAM slot.

Currently hard coded to slot #4.

Do a last pass on table and branch alignment to avoid crossing page boundaries

When you're calling the main plot function ~1 million times across the sequence, every extra cycle adds up...

Wait until code has finished (and turn off _DEBUG define).

Fix Model B ROM slot bug.

Can't read from &FE30 - need to read from &F4 instead!
Ensure no random crashes - ask folks to test on real Model B hw.
Ensure runs through on b-em.

Check / unbreak Model B version for post-party release

I've almost certainly broken the B version whilst focusing on Master model only for party version.

Fix looping.

Demo is supposed to loop but currently doesn't.
Figure we should just leave looping on by default, user can press BREAK.

Some kind of intro?

We'll almost certainly want some kind of intro at the start to call out the specs of the machine:

BBC w/ 32K RAM (+16K? for music)
No VIC, no blitter etc.
Real floppy discs
2MHz 6502 CPU

Oh and a Bitshifters logo somewhere as well, I'm sure. :)

NULA version?

It would be possible to make a custom NULA version that runs in MODE 8 but with full 16 colour palette. Not sure what to do about the resolution though as 64x100 is going to look super-chunky.

There might be some optimisations to be made since we wouldn't require the dithering pattern for the palette?

Can Medium Quality use a different dither byte per scanline?

In MQ the exact same scanline is duplicated for the second (odd) line by running the plot routine twice with the same palette byte. It shouldn't be that hard to increment the palette lookup so the second line is using the correct palette byte for the odd scanline. This would increase the apparent resolution and might be virtually indistinguishable from HQ.

Crashes on Model B around frame 141

Works fine on Master (emulated and real hw).
Doesn't use any Master CPU specific instructions so not sure what's going on here!

Toggle music on/off in Intro with key press.

Only time this is vaguely useful is when the demo is left on loop at Acorn World and I'm going nuts from hearing the tunes for the 100x.

Single drive version

For the determined completist with only one disk drive: a version that has a disk swap message, waiting for a keypress, so you can still see the whole thing.

Add real time clock?

Some versions of the demo have a clock (minutes:seconds:frames) either during the whole thing or at the end to indicate the speed. Perhaps not a great idea considering this is hardly the fastest version (!!) but might be of interest to some.

Check Intro for raster glitches on real hw.

Noticed that the Xmas demo looked way worse on real hw than on any of the emulators.
Want this to be as good as possible!

Update README for v1.1

Sort out the colour palette and dither patterns

The original colour palette and dither patterns were a lucky guess + MODE 5 defaults!

Need to have a look at the palette data in the stream to see if it is worth redefining the palette at various points in the sequence. How much can be pre-baked?

What dither patterns actually look best with the selected palette colour values?

What dither patterns should be used for the medium / low quality settings as these can turn into a pixellated mess quite easily?

Outro doesn't clear the screen before re-running the intro

There's a bit of the bitshifters symbol left on screen, at least in b2. Is this something that can be fixed easily enough?

Find the best possible Timer 1 value before release

Worth a few runs adjusting the TImer 1 value as low as we can get away with to minimise the overal frame rate but not starve the disk streaming code.

Can pre-divide all vertices in the data stream.

Thought I'd done this already but at the moment only the X values in the de-interleaved indexed vertex data has been pre-divided by 2.

Music!

Integrate most recent / optimised music player (is this from Wave Runner or use Simon's LZ compressor?)

Pick awesome music, ideally an SN version of ChechnoBankh if we can..

Inline plot functions

Once we believe there's no more juice to squeeze out of the code, final optimisation would be to directly inline the plot_span function into plot_poly_span and maybe even inline plot_poly_span into parse_frame.

This would remove the 6c JMP/JMP overhead per fn call which is considerable across the entire sequence. It will, however, make the code very hard to read / maintain.

Fix degenerate polys in low & medium quality

Halving both the horizontal and vertical vertex coordinates can leave some degenerate (single point) polys which aren’t handled very well. End up with a two pixel dash on the edge of a line because the span buffer isn’t set correctly. Need to filter these out in quality modes < high.

Check streaming works on MMFS type systems

Last time I tried, streaming didn't work on my B with a recent version of MMFS. Possible regression in MMFS for OSWORD &7F implementation as had problems getting Bad Apple to run as well and sure this was OK previously.

Might need to implement the same disc speed test as Bad Apple and change streaming to sector-by-sector load rather than track-by-track as the latter caused stuttering / slowdown on Bad Apple.

Open questions regarding NuLA quality level and overall timing

The batch files a quality=1 NuLA build, which looks pretty nice. The makefile build creates a quality=0 NuLA build, because then the demo finishes before the music, rather than the other way around.

4b481dc adds a delay to the NuLA version so the quality=0 version runs in the same time as the non-NuLA version, so it finishes in time with the music. (Haven't tried this on real hardware, though... just b2.)

The quality=0 build does look a bit dim, of course, which might be objectionable. So perhaps we want quality=1 after all, get rid of the delay, avoid the temptation to re-open #25, and just live with the music finishing early?

Create a BEEB.MMB image for distribution

Since setting up 4x individual SSD images in the correct drives could be a challenge for some users, it would be nice to create a BEEB.MMB image that contains the 4x disk images in the correct order and autoboot.

Details of the MMB format can be found here: https://sweh.spuddy.org/Beeb/mmb_utils.html

Unbreak NULA version for post-party release

I done broken the NULA version for the party version. Sorry.

Middle of the animation sequence looks a bit of a mess.

Need to do another pass on ST palette => BBC dither mapping.
The start and end of the sequence look good but the middle parts turn into a bit of a pixellated mess.
Try using more contrasting dither patterns - fewer middle values, push to extremes (either almost empty or almost filled).
Are there any occasions when it is possible to mix up the colours a bit to make it more solid?
Hate the green/yellow combination of the boring pentagonal tunnel. Can we swap one of the colours for something else? Even if the palette switch is obvious? (Need yellow for the blue tunnel later on and using green as come out of a very green tunnel beforehand). Perhaps cyan would be better?