shadow of the beast ST (Mark mc cubbin here)

[Cyprian]

Apologies it was Joefish who did the demo! Will amend my post...

https://www.youtube.com/watch?v=NRMOan38qRU

the impossible becomes possible. It runs at 50fps on a stock 520ST with 512kB ram.

well done @joefish


I've just submitted it to the Pouet: https://www.pouet.net/prod.php?which=88890

It's 25fps mate

25fps ? I'm a bit confused. I've just checked that under Steem Debugger and I see that the screen (trees, hills, grass, clouds) is changed every frame - 50fps not 25fps

[Dbug]

It's clearly not running in 1vbl, and even the first comment on the videos says it:

It takes just over one frame to redraw the scenery, so runs at 25fps.

[Cyprian]

Dbug, as I mentioned I'm confused. I've checked (under TOS 1.04 DE - 50Hz) more than hundred VBLs, and trees, hills, grass, clouds move on VBL basis.
Just for an example, below you can find eight (the forum limit) consecutive VBL screenshots taken under Steem Debuger.
On each of them the background is in a different position, and the sprites (the beast) differs on every second.

BEAST010_00001.png

BEAST010_00002.png

BEAST010_00003.png

BEAST010_00004.png

BEAST010_00005.png

BEAST010_00006.png

BEAST010_00007.png

BEAST010_00008.png

[Cyprian]

ok, my fault,
previously I did some tests on 16Mhz and I just forgot to switch to 8Mhz

And that's true on 8Mhz it is 2VBLs

[Dbug]

Lol, that explains.

Another thing to remember, the MegaSTe does not run at 16mhz: Only the CPU and the cache are, so ultimately for code that is doing intensive memory accesses, you don't have the double speed, you only get the double speed on the actual internal CPU operations, and eventually on the cached part of the code, but the loading of the bitmap data and the writing to screen memory would still be at 8mhz.

[Cyprian]

yep,

[chicane]

I've put together a quick video that shows in slow motion the drawing of a single frame in SOTB, and posted it on Twitter. Thought it might be of interest to folks here:

https://twitter.com/RetroRacing/status/ ... 0924097537

[Cyprian]

nice one,
it looks that clouds and mountains are drawn in one go. is it correct?

[chicane]

Yes - that video reflects exactly what's going on in the back buffer, so it looks like the background layer is drawn in one pass from top to bottom.

[GagHalfrunt]

Really interesting thread, especially given how disappointed I was with the ST port. My brother got a second-hand C64 with it on cartridge and I think I enjoyed it more on there!

If we are talking STe, I still get surprised when people talk about 512KB. Back in the day I was a poor kid with my 520STe and even I had 1MB due to Atari's wise decision to use SIMMs. The price of them plummeted, mine were salvaged from a PC user and purchased second-hand. I would love to see a 1MB STe version just to prove it could be done although granted the gameplay wasn't the best.

[MegaSTEarian]

A Falcon version (like the AGA conversions in the Amiga scene) would also be really good as well.

[ragnar76]

Thanks for this very interesting thread. I've never played it on a st(e) but I was literally blown away when Ive played it on the lynx.

[metalages]

. I would love to see a 1MB STe version just to prove it could be done although granted the gameplay wasn't the best.

You have phaleon demo menu at least.

[Dbug]

. I would love to see a 1MB STe version just to prove it could be done although granted the gameplay wasn't the best.

You have phaleon demo menu at least.

The phaleon demo is running fine on STf as well, nothing STe specific in it other than the better color gradients

Also there are no ennemies, that makes things quite easier

[metalages]

In fullscreen if I well remember ?

[Dbug]

Left and right overscan, gave this "cinemascope" effect

[joefish]

Thanks for the interest again! Yes, my demo is updating at 25fps. It redraws about 80% of the screen in one frame. To finish off the fence at the bottom and add the software sprites tips it into the next frame, but then it's just sitting idle for about half a frame until the next vertical interrupt. As I say in the video notes, the main trick is to repaint the trees in just 2 shades of poo and a greenie so they only need 2 bitplanes.

The trick with that Phaleon demo is the parallax only really takes place above the main sprites' head. There's a different palette setup in that section so it only uses 8 colours leaving one whole bitplane for the background. But the character can never jump up as its colours don't exist in that upper palette. Side border removal is neat and I assume there's hardware scrolling going on there rather than repainting the entire screen from software.

Mind you, that's quite like the trick SotB3 does on the Amiga. The player is always in the bottom 1/3 of the screen. The parallax iceberg background is done with repeating sprites across the middle of the screen, but they're always kept above the player's head so that the same sprites can be multiplexed to display the actual player, and your lives, health, etc. on other rows of the screen.

I guess on an STE what you'd do is hardware scroll the whole screen in one direction, then software repaint one of the parallax layers to counter-scroll it so it looks like a different speed. I don't know if the blitter can single-out specific bitplanes to help. Unfortunately I know from software that updating two bitplanes isn't a huge amount faster than updating the whole screen, since you have to keep skipping over every 4 out of every 8 bytes as you go, when you could just be copying to all 8 bytes, but at least it could be done at 50fps.

The problem with 50fps software scrolling on a regular ST is you get a finer scroll, so need twice as much pre-shifted data to do it!

[Cyprian]

what about shrinking the screen area to Amiga size - 288 x 192? Would be possible to fit in one frame?

[DarkLord]

I'd like to see Shadow of the Beast (and a lot of other titles) be
re-made using Doug Little's game engine tools:

[A]tari [G]ame [T]ools - 2D prototyping engine for STE

I know a lot of work would be involved and it will probably
never happen...but one can dream.

[joefish]

what about shrinking the screen area to Amiga size - 288 x 192? Would be possible to fit in one frame?

That wouldn't be saving a huge amount of time, but it'd help. I expect that if a better programmer went over my code with instruction-specific optimisations in mind, and shrinking the screen a little, and maybe had 1Meg on hand both for pre-shifted imagery, and hundreds of slightly different 'copy-one-line' functions prepared (rather than re-writing the copy function every time you scroll), you could just about get the scrolling done in one frame and thus get to 50fps.

But then it'd be a real stretch to mask in a large sprite like the player character as well. You'd probably have to cut away yet more of the screen to do that.