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Old 20 April 2023, 23:40   #61
Toffee
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Originally Posted by TCD View Post
Interesting. I was always wondering why the effect looks so smooth. Thank you for the explanation

Edit: I should have written 'zooming out' now that I read my post...
It's like the Amiga Copper register 102 zoom which can just reduce the size of an image before it's displayed on the screen.

Apart from it was actually designed for this and not severely limted!

Last edited by Toffee; 20 April 2023 at 23:53.
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Old 20 April 2023, 23:47   #62
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Originally Posted by sokolovic View Post
Team17 wanted to add this kind of effect on Alien Breed 2 when it was intented to be just an A1200 version. It was ditched when they finally decided that the AGA version will be just an enhanced OCS one. Anyway, I'm not sure it was even possible. Seems a bit heavy for a basic Amiga OCS or AGA but who knows, they did managed to get this effect on Art of Fighting on the PC Engine CD.
I remember reading this about Alien Breed 2 AGA in magazine previews at the time.

They must have been thinking of the scroll register zoom but probably found it to limiting as it can only scale an image down by 16 pixels. You would have needed tile/sprites in multiple sizes of 16 pixels. Also it wouldn't have worked with AGA 4x mode as well thinking about it and scrolling might have been a nightmare.

Last edited by Toffee; 20 April 2023 at 23:55.
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Old 20 April 2023, 23:51   #63
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Wink

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The sequel blows the original away!!!

[ Show youtube player ]
Yes awesome demo!

We should have a competition on the Amiga on how many more checkerboard layers we can have!

https://www.pouet.net/prod.php?which=74681
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Old 21 April 2023, 02:39   #64
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Quote:
Originally Posted by Toffee View Post
It's like the Amiga Copper register 102 zoom which can just reduce the size of an image before it's displayed on the screen.

Apart from it was actually designed for this and not severely limted!
Copper and modulo can invert, stretch and compress images vertically. Horizontally, Amiga chipsets are not capable of scaling, stretching nor inverting imaging. It only gets jobs half-done.
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Old 21 April 2023, 07:23   #65
TCD
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Copper and modulo can invert, stretch and compress images vertically. Horizontally, Amiga chipsets are not capable of scaling, stretching nor inverting imaging. It only gets jobs half-done.
Would create an interesting effect I'd imagine
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Old 21 April 2023, 07:47   #66
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Originally Posted by Samurai_Crow View Post
Copper and modulo can invert, stretch and compress images vertically. Horizontally, Amiga chipsets are not capable of scaling, stretching nor inverting imaging. It only gets jobs half-done.
You could reverse the viewpoint by thinking that you only have to do other half of the job in software. I guess that was how they managed to add these impressive zoom effect in Mr Nutz or Brian the Lion (also Dune use a nice effect, blurring the screen and distorting the image when you're on Spice).
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Old 21 April 2023, 09:19   #67
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Is there really a difference between planar and chunky display for 3D using a 68000/7mhz CPU ?
Of course, C2P routines are the main problem when you do 3D on the slow amiga .
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Old 21 April 2023, 10:36   #68
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Of course, C2P routines are the main problem when you do 3D on the slow amiga .
But even with it chunky display the Megadrive doesn't seems to have more detailed or smoother 3D games than the basic Amiga 500. Plus the Amiga can be expanded to accelerate 3D games. Megadrive is stuck with its 68000/7,6 MHz cpu. Chunky or not, you'll have trouble to display many plain (let alone textured) polygons at a decent rate.

Last edited by sokolovic; 21 April 2023 at 11:09.
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Old 21 April 2023, 12:09   #69
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I'd say the A1200 is better than or at least competing with the Megadrive on most gaming applications.
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Old 21 April 2023, 15:02   #70
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Originally Posted by Samurai_Crow View Post
Copper and modulo can invert, stretch and compress images vertically. Horizontally, Amiga chipsets are not capable of scaling, stretching nor inverting imaging. It only gets jobs half-done.
If you change the value of scroll register/BPLCON1/$dff102 across the scan line from lets say $88 to $77 it will skip a pixel. This allows you to scale a bitmap horizontally by upto 16 pixels with carefull timing of the Copper chip.

Here is an example from Sanity Jesterday with the awesome profiling tool from Abyss/Bartman.

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Old 21 April 2023, 15:06   #71
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Up to 16 pixels per row? So it's 60% done instead of half-done.
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Old 21 April 2023, 15:10   #72
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Up to 16 pixels per row? So it's 60% done instead of half-done.
It's very limiting and also can only shrink not expand. You also only have limited places across the scan line that you can skip a pixel.

60% done is probably optimistic. What is neat is that you can of course change the zoom value per line.
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Old 21 April 2023, 15:17   #73
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It's very limiting and also can only shrink not expand. You also only have limited places across the scan line that you can skip a pixel.

60% done is probably optimistic. What is neat is that you can of course change the zoom value per line.
Agreed. Copper moves can be expensive on systems with no Fast RAM also.
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Old 22 April 2023, 10:48   #74
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Megadrive's main advantage was lots of hardware sprites right? That lead to better arcade ports
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Old 22 April 2023, 10:54   #75
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Megadrive's main advantage was lots of hardware sprites right?
Correct. As others have pointed out that advantage is not that important compared to the A1200 though.
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Old 22 April 2023, 13:38   #76
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Megadrive's main advantage was lots of hardware sprites right? That lead to better arcade ports
Another advantage was a slightly faster 68000, but developers really pushed the CPU to its limits for sample playback, sprite scaling/rotation, etc. Meanwhile the A1200's 68020 stays idle for most of the time
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Old 22 April 2023, 14:02   #77
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The Megadrive had a bonus Z80 processor for an extra 3.54Mhz too, most programmers just used it for sound but it could be exploited for extra 3D routines. The 14Mhz A1200 should still give better results though, even without fast RAM.
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Old 22 April 2023, 14:53   #78
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Correct. As others have pointed out that advantage is not that important compared to the A1200 though.
Imho (and unfortunately) it seems it is. Despite a1200s other benefits (better color, more overall flexibility, sprite plus blitter options, copper, faster processor and better performance for 3d stuff) for arcade quality like games it still lags a bit behind the Mega Drive. A1200's same old blitter is the bottleneck here, despite better performance compared to a500, it is just by a very thin margin. So while the Mega Drive can move with ease dozens of objects on screen while also having several layers of parallax and doing all these under 50fps, it is exceedingly difficult and without big compromises for a1200 to do the same. Take a game like Aladdin f.e. the Mega Drive version is clearly superior. Now while I'm not exactly sure how better it could be or how good of a job they did, it's still a comparable real-life result that (perhaps) tells a lot about the abilities of the two machines.
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Old 22 April 2023, 15:02   #79
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Can we just call it a draw and move on then?

Seriously though, just check the second post in this thread: https://eab.abime.net/showthread.php?t=100336

I don't think there will ever be a clear 'a is better than b' answer because there's also a good bit of subjectivity in what is 'better'.
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Old 22 April 2023, 15:20   #80
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Imho (and unfortunately) it seems it is. Despite a1200s other benefits (better color, more overall flexibility, sprite plus blitter options, copper, faster processor and better performance for 3d stuff) for arcade quality like games it still lags a bit behind the Mega Drive. A1200's same old blitter is the bottleneck here, despite better performance compared to a500, it is just by a very thin margin. So while the Mega Drive can move with ease dozens of objects on screen while also having several layers of parallax and doing all these under 50fps, it is exceedingly difficult and without big compromises for a1200 to do the same. Take a game like Aladdin f.e. the Mega Drive version is clearly superior. Now while I'm not exactly sure how better it could be or how good of a job they did, it's still a comparable real-life result that (perhaps) tells a lot about the abilities of the two machines.
Maybe that's because you seems to think that horizontal scrolling games with parallaxes and many sprites are the only benchmark of 2D gfx abilities ?

A game like Slam Tilt is impossible to do on the Megadrive. And even, look at Worms Megadrive version vs Worms DC on the 1200.

Plus it would be honest to say that Aladdin was designed for the Megadrive first. The Amiga version is a port made by just one coder
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