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Old 26 February 2017, 15:11   #81
frank_b
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Mcoder must have tried using Atari's generic bitblt function from the blitter manual. That has a ridiculous overhead as it's really generic. I used MCoders sprite technique (it's clever) in the blitter intro I released on Atari forum. It's 2.8 times slower than using the ST blitter Don't take my word for it. Download the intro/benchmark and see. Even preshifting was slower than brute force AND/OR masking. You cannot beat 24 cycles a word for fully masking on a 68k. Hardware always wins. Here's an ST (not STe) game which mandates using the blitter. [ Show youtube player ] It's doing double duty drawing sprites and scrolling the screen. It runs at 50hz.
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Old 26 February 2017, 19:26   #82
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Originally Posted by idrougge View Post
The biggest problem with the ST blitter was that you couldn't count on it being there. Hence no games or demos made use of it.
The same argument is valid about machines having 1 MB of RAM instead of 512 kB.

However, the difference is also that you only need a small alternative code path for the Blitter drawing and you're done. So, in fact, there are Atari ST games which use the Blitter when it is detected.
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Old 26 February 2017, 19:30   #83
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So, in fact, there are Atari ST games which use the Blitter when it is detected.
Please name both of them
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Old 26 February 2017, 20:24   #84
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Please name both of them
Power drift, chronicles of omega, lethal xcess, wings of death, ghost battle, Elvira the arcade game, zool, Cisco heat. Star dust, obsession, great giana sisters remix, pole position conversion, maniac mansion, Giana blitter enhanced, sub station and some others
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Old 26 February 2017, 20:38   #85
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http://www.atari-forum.com/viewtopic...12530&start=25"What ? It's a myth !!! Indeed, the Amiga had seperated bitplans (on the ST, they are consecutives), so the filling up is in pratical way more faster. But since the Amiga programmers were globally way less gifted... (than the ST coders)"
I don't get the point here. Maybe I don't understand argument at all!?

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"The STE is nothing to write home about. The STE blitter is incredibly shitty: for Toki, i had tested the blitter, and frankly, my SOFTWARE sprites routine was running faster than the hardware !!! About the hardware scroll: what's the point, since the game must run on ST too ???"
Too bad he only tested the Blitter. There are many ways to use it more effectively and frank_b is right: he just used the "recommended" way for drawing sprites.
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Old 26 February 2017, 22:22   #86
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I don't get the point here. Maybe I don't understand argument at all!?


Too bad he only tested the Blitter. There are many ways to use it more effectively and frank_b is right: he just used the "recommended" way for drawing sprites.
I think he must have tried to use the bitblit sample from the manual. That one has a 900 cycle overhead for every blit. A simple NOT AND, OR set of ops is around 2.6 times faster than his algorithm for drawing software sprites. It's around 5.8-8x times faster than a naive algorithm and about 20% faster than a pre shifted routine. It uses something like 20x less memory for data in the pre shifted case. The blitter has the raw blitblit performance of a 48+ mhz 68000. The STE has better bitblit performance than a fast RAM equipped Atari TT. Your method of using the intelligent end masks is around 50% faster at least than the brute force method. The CPU loses badly in all cases just like it would on the Amiga CPU vs the blitter. Insisting on using the CPU for "speed" vs the blitter is really stupid IMHO. It will have been driven by time to market and QA time demands.

Last edited by frank_b; 27 February 2017 at 02:31.
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Old 27 February 2017, 20:16   #87
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The same argument is valid about machines having 1 MB of RAM instead of 512 kB.
Indeed it is – ST computers were very difficult to upgrade to 1 MB, hence there are very few games requiring so much RAM even though it was very desirable on a non-blitter system because no blitter and no hardware scrolling calls for use of preshifted graphics.

Quote:
Originally Posted by AnimaInCorpore
However, the difference is also that you only need a small alternative code path for the Blitter drawing and you're done. So, in fact, there are Atari ST games which use the Blitter when it is detected.
Which will cost developer time and eat away at the valuable 512 kB memory which has been filled up with pre-shifted "sprites" and playfields.
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Old 27 February 2017, 20:23   #88
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Indeed it is – ST computers were very difficult to upgrade to 1 MB, hence there are very few games requiring so much RAM even though it was very desirable on a non-blitter system because no blitter and no hardware scrolling calls for use of preshifted graphics.



Which will cost developer time and eat away at the valuable 512 kB memory which has been filled up with pre-shifted "sprites" and playfields.
Why would you need to preshift sprites if you have access to a blitter?
It's one or the other.
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Old 28 February 2017, 10:49   #89
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You may not need to preshift sprites, but without hardware scrolling, you may want to preshift backgrounds nevertheless. And your precious 512 kB memory must hold two codepaths instead of one.
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Old 28 February 2017, 11:11   #90
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You may not need to preshift sprites, but without hardware scrolling, you may want to preshift backgrounds nevertheless. And your precious 512 kB memory must hold two codepaths instead of one.
No. You can also have different binaries on your disk.

Also the STE improved versions of Giana Sisters and Pac-Mania show that it isn't impossible to add an appropriate code path without changing too much.
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Old 28 February 2017, 11:28   #91
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No. You can also have different binaries on your disk.

Also the STE improved versions of Giana Sisters and Pac-Mania show that it isn't impossible to add an appropriate code path without changing too much.
Yep. And if disk space was a problem, you could use the slightly less nice option of just overwriting part of the code with pre-shifted graphics if no blitter is detected. A bit more work, but should be possible.

You could even store extra animation frames etc for the blitter version and overwrite those with pre-shifted graphics if no blitter is present. Again, harder to do, but not impossible.
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Old 28 February 2017, 12:51   #92
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Never did I say it was impossible – all options you list are viable if you have the time to spare.

But in a real-life situation, the ST blitter is not an option since so much of your time is already spent on handing blitter-less machines.
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Old 28 February 2017, 14:49   #93
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You may not need to preshift sprites, but without hardware scrolling, you may want to preshift backgrounds nevertheless. And your precious 512 kB memory must hold two codepaths instead of one.
You could use the blitter to scroll the screen too. It would cost you about 75% of a VBL for four planes full screen but it's doable. It's fast enough to chuck the whole screen around in a frame with a bitplane's worth of bandwidth left.

A sprite routine with the blitter is a couple of dozen CPU instructions at most. Scrolling the screen is 4x that much instruction overhead at most. The overhead is negligible. The memory savings at runtime are massive. With pre shifting a 32*32 1 plane sprite would be 3 words wide (one for shift span) * 32 * 16 if you want to put it on a pixel boundry. The blitter can use graphics stored 2 words wide, there's no need for a pre shift or extra word per row. The destination can be wider than the source. The hardware is optimised for this. It only needs to read the source as two words but can write out three to account for shifting.

Games which use it prior to the STE are rare but they do exist. It should have been present on the original machine at launch day.
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Old 01 March 2017, 08:48   #94
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But in a real-life situation, the ST blitter is not an option since so much of your time is already spent on handing blitter-less machines.
It's not really that much time you need to understand the Atari ST Blitter to get viable results compared to the Amiga Blitter.

Anyway, adding scrolling capabilities, the Blitter and PCM sound to the Atari STE closes the gap to the Amiga by a fair margin.

Last edited by AnimaInCorpore; 01 March 2017 at 12:17.
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Old 02 March 2017, 15:00   #95
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One thing that a lot of die hard ST users say is, the STE had much better hardware than the ST and they didn't use it properly, or it was a lazy rushed port. All that stuff being completely irrelevant, history has already been played out, all the excuses after the fact doesn't change anything. The ST was an OK machine, was never great, it filled a nice gap in the market for being affordable.

There will never be a game like Elf Mania or Lionheart on the ST, even with all the time in the world. Hypotheticals are all very fine but in the end that's all they are. I love the ST, it was my first 16-bit computer, but I realise the machines limits. Can't we just say the ST was a fine machine but will forever live in the Shadow of the Amiga.

Shadow Of The Amiga - Possible game title? Haha!
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Old 02 March 2017, 16:40   #96
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Here is a Turtles Coin-op comparison, the Amiga and ST versions are at the end of the video:
[ Show youtube player ]

Scrolling is smoother on the Amiga, but according to this video, ST version has music and Amiga version doesn't.

---

Also the differences in Darius+ are interesting:

Atari ST
[ Show youtube player ]

Amiga:
[ Show youtube player ]

On the Amiga also the second background layer scrolls, while in the ST version it does not. And also in the Amiga version a few colors in the palette are changed at certain points, giving the enemies in each attack wave slightly different colors. Although I'm not sure if the ST version does this palette swapping too. But to me it seems that they seriously tried to make the Amiga version better.
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Old 02 March 2017, 17:28   #97
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I think Darius+ is hopeless on both machines. You can see on YouTube.
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Old 02 March 2017, 18:36   #98
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I don't think there is anything added but some "mould" on the blocks. To me everything looks like the palette has been badly changed and all the colours are wrong everywhere. Just horrible. Only blind person can say it looks better...
Agreed. Just did a side-by-side comparison of the st and the Amiga, and the pallette on the st is terrible. At first I though my version of the game was corrupt!
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Old 02 March 2017, 22:16   #99
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Quote:
Originally Posted by Master484 View Post
Here is a Turtles Coin-op comparison, the Amiga and ST versions are at the end of the video:
[ Show youtube player ]

Scrolling is smoother on the Amiga, but according to this video, ST version has music and Amiga version doesn't.

---

Also the differences in Darius+ are interesting:

Atari ST
[ Show youtube player ]

Amiga:
[ Show youtube player ]

On the Amiga also the second background layer scrolls, while in the ST version it does not. And also in the Amiga version a few colors in the palette are changed at certain points, giving the enemies in each attack wave slightly different colors. Although I'm not sure if the ST version does this palette swapping too. But to me it seems that they seriously tried to make the Amiga version better.
for TMNT coin-op, the Amiga version has music, but it's not used unfortunately. It was a port made from the Atari ST.

Darius+ is a piece of junk.
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Old 03 March 2017, 13:04   #100
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Has Nitro been mentioned? Apparently this version has pedestrians and traffic on Atari but not on Amiga.
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