new amiga 500 doom like !

[rothers]

In the demo chat video it's funny seeing people refuse to believe it can be real, word is spreading.

[ExiE]

Take Fears f.e. despite having a good engine with plenty features, good gfx and great atmoshpere, it failed quite a lot (imho) to compare from a gameplay perspective. Why? Let's break this down a bit:


For me the biggest problem with Fear was the distorted perspective. I could live with slow movement and small variety of enemies but I simply couldn't watch it...

[gimbal]

Originally Posted by ExiE

For me the biggest problem with Fear was the distorted perspective.

I wouldn't say distorted... it reminds me of Descent, it's a little disorienting maybe. But that is mostly to do with the low resolution to be honest.

[ESC]

As I understand it Fears looks weird because it's stretched out from a very narrow resolution, since they don't compensate for this it makes the FOV very low which in turn makes me feel a bit queasy playing it.

Tsak posted this earlier in the thread:

Originally Posted by Tsak

-Alien Breed 3D: 96x78
-Fears: 92x128 (top HUD part was missing in my previous pic)
-Dread: 320x100

Originally Posted by KK/Altair

Not really. Just the usual overcoming of generic platform quirks and a few new procedures for CPU drawing menus, status bar and weapons to the ST screen.
Playing SFX on STe was fun, because I had to come up with a way to play reasonably using only one channel - and a short queue plus minimal playing time for each sound did the trick.
Still, I was kind of disappointed with how C2P has to be done. The usual ST trickery wasn't even close to what I did with Blitter, and having extra LUT reduced logical pixel color combinations from 256 to 64, mostly destroying the new extra resolution trick.

Oh, the ST only has one SFX-channel? that I didn't know. In all honesty I know very little about the ST-family of computers, I have a 520 here at home that I picked up in a flea market a couple of years back that I hardly use, it's interesting reading this anyway, but I assume the fact that you weren't able to use any hardware tricks is the reason that the ST-version will require 2MB of ram instead of 1MB?

Oh btw, in the video there's a soundtrack, is that an official one or is that a placeholder?

[ExiE]

Originally Posted by gimbal

I wouldn't say distorted... it reminds me of Descent, it's a little disorienting maybe. But that is mostly to do with the low resolution to be honest.

No no no, Descent is perfectly fine, great game.

Depth of the image (z-value) of Fear looks too short or flattened.

[KK/Altair]

If you want to take the maximum capabilities of STE's blitter, take a look at EMX2 sprite format from DML at Atari Game Tools Engine.

Do you have any more technical info on that?

As well a 2 Channel PCM mixer at 12 or less KHz will take 3% of CPU time. If STE its the target, you can take the advantage of 4 MB RAM (precalculate, or preshift textures into RAM) with no major problem.

1-channel with SFX queue feels enough for now, and I'd like to focus on optimizing stuff on ST, not adding features now.
My texturing doesn't need any preshifting right now, and I don't see how it would help in my approach.

Also you can get rid of YM2149 usage in favour of performance.

Yes, disabling YM music helps quite a bit. But it can be done from the menu already, so I don't see a point in removing it completely.

I wouldn't say distorted... it reminds me of Descent, it's a little disorienting maybe.

Ah, Descent... its 6 DOF was what was really disorienting.

Oh, the ST only has one SFX-channel? that I didn't know. In all honesty I know very little about the ST-family of computers

I knew very little about ST family, too.
Yes, STe has only one channel, with fixed volume and 4 fixed playback rates.
So you can only playback ready samples as they are, or have to mix stuff.
But the former option worked well enough for me.

but I assume the fact that you weren't able to use any hardware tricks is the reason that the ST-version will require 2MB of ram instead of 1MB?

It requires 2 MB because I didn't really care to optimize it and 4MB ST's are fairly common.

Oh btw, in the video there's a soundtrack, is that an official one or is that a placeholder?

It's currently official for the ST version. Grey/MSB helped me get in touch with DMA-sc, who did two pieces (menu & ingame).
Amiga will have its own in due time, when audio engine is capable of playing music.

[alexh]

Originally Posted by KK/Altair

Do you have any more technical info on that?

https://bitbucket.org/d_m_l/agtools/wiki/Home
https://bitbucket.org/d_m_l/agtools/wiki/agtcut

I think it was Anima who came up with the idea and DML who optimised it.

http://blog.anides.de/

[KK/Altair]

Originally Posted by alexh

https://bitbucket.org/d_m_l/agtools/wiki/Home
https://bitbucket.org/d_m_l/agtools/wiki/agtcut

Ok, but it would be complete information about Blitter internals, what interests me most right now.
Not fragments of code, which don't really tell WHY they are written like that.


On Amiga, I learned how to calculate Blitter cycles exactly, ane exactly how CPU, Blitter, Copper, display, audio, disk and RAM refreshes share the bus, which enables me to write effective code.


On the ST side, I've only got vague suggestions and pointers to AGT source code, but no real information about Blitter or ST internals. And I can't even start optimizing without the latter.

[alexh]

Originally Posted by KK/Altair

complete information about Blitter internals, what interests me most right now.

Maybe Jorge Cwik (Ijor). He recreated a cycle accurate Atari ST chipset including the 68000 and Blitter in HDL for FPGAs called FX-CAST.

https://www.atari-forum.com/viewtopic.php?f=117&t=34555

These are the only docs I remember reading :

https://retrospec.sgn.net/users/tomc...0Internals.htm
https://info-coach.fr/atari/document...ts/BLITTER.TXT

There was a little chat last year with Keops (well respected Atari STf programmer) who wanted to start using Blitter. Some very big Atari ST names (like Ijor and Leonard) commented.

https://www.atari-forum.com/viewtopic.php?t=38994

[frank_b]

http://dev-docs.exxoshost.co.uk/BLiTTER_6-17-1987.pdf is the official reference manual.

The trick anima invented was to do single pass masking with it for fast bobs which should be impossible to do with a single source and dest.

It has 3 end masks. First word mask, Middle word mask and end word mask for preserving bits in the fringes during a blit. Unlike the Amiga the masks protect bits in the destination rather than masking the source.
So you can just blit line by line with the CPU and preload the preshifted mask on every line to mask arbitrary 32 pixel wide bobs without a separate AND and OR pass.

What do you use the Amiga one for in the game?
It works in a similar manner to the Amigas but with 2 sources not 3. The dest is also a source.
There’s 16 words of memory on the chip which can be used in place of the source for some interesting tricks.
It has no line draw or area fill but it does have an indirect addressing mode which can be useful for some stuff like magnification, mono bit plane palette expansion to true colour or flipping rasters. It also has a full 24 bit addressing range.
It has a barrel shifter too. It’s awesome, just like the Amigas

[tomcat666]

Of course you know the amiga version MUST be better than ST in every aspect, if not then the ST crowd will win the decades long argument and all will be lost.
We will all have to buy ST's, oh the shame of it. Not sure how many will survive...

[Havie]

Originally Posted by tomcat666

Of course you know the amiga version MUST be better than ST in every aspect, if not then the ST crowd will win the decades long argument and all will be lost.
We will all have to buy ST's, oh the shame of it. Not sure how many will survive...

I'm sure KK won't let us down on this but I can't believe he went to the dark side!

[turrican3]

Originally Posted by tomcat666

Of course you know the amiga version MUST be better than ST in every aspect, if not then the ST crowd will win the decades long argument and all will be lost.
We will all have to buy ST's, oh the shame of it. Not sure how many will survive...

from what i saw, graphically the amiga seems to look better, for the rest, will see. The music will certainly be better. The number of fps is the ???
Will see.

[KK/Altair]

What do you use the Amiga one for in the game?

Chunky 2 planar. I'm using 2 full screen (320x160) Blitter passes to extract bits from chunky and create planar display. The first pass also does the transposition. Blitter is completely driven by interrupts, so CPU is free to process next frame.

[frank_b]

What kind of blit? How many sources do you use? Do you shift a and b? Any constant masks?
If it is a complex use case or takes advantages of pipeline side effects it might not be a good fit for the ST blitter. Complex use cases fit the Amiga one better. The st does well with simpler operations.
Looks like there are demo crews using the indirect addressing mode to accelerate chunky pixel to planar on the st blitter. https://docs.dev-docs.org/htm/search.php?find=blitter Look at the paranoid faq for details. Years ago I used it to magnify bitmaps or h flip them in a poc. A single pass would be 8 or 12 cpu cycles depending on the logic operations used.

[Tsak]

Originally Posted by turrican3

from what i saw, graphically the amiga seems to look better, for the rest, will see. The music will certainly be better. The number of fps is the ???
Will see.

Yes, ST version lacks sprites (weapons) and smooth weapons movement. It also lacks on the resolution due to fewer pixel pair combinations available (64 vs 256). On plain ST colors quality is also worse as well as sfx quality. Lastly performance is currently slightly better on Amiga but might get better on ST-STe if KK does further optimisations.

In regards to fps the game reaches ~10-12 fps on average for a500 and gets a good additional boost with a1200 (around 22fps). It maxes out to 30fps with a1200+fast ram or a better processor.

[sparhawk]

Originally Posted by tomcat666

Of course you know the amiga version MUST be better than ST in every aspect, if not then the ST crowd will win the decades long argument and all will be lost.

ST already lost it, as this project proves. After all it was ported FROM the Amiga to ST, as it always should have been, not the other way around.

We will all have to buy ST's, oh the shame of it.

Only when I need a new doorstopper.

BTW: The ST also has a Blitter??? Or am I missunderstanding something?

[d4rk3lf]

Maybe KK is preparing to give final blow to Atari users...
He is working on Dread port, and suddenly announces: "No, it's not possible for Atari ST(e)".

(joke aside, I never had anything against Atari and it's users, on the contrary, I consider them more like a Motorola brothers ).

[vulture]

@sparhawk

STe has a blitter yes. AFAIK it's overall a weaker design than amiga's, but it's an improvement for the ST

[tomcat666]

Originally Posted by vulture

@sparhawk

STe has a blitter yes. AFAIK it's overall a weaker design than amiga's, but it's an improvement for the ST

Not every ST has a blitter... actually most of the ST's sold back in the day did NOT have one, so not many games actually supported it.