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Old 08 March 2018, 12:43   #21
Coagulus
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I'm sure I remember a pd racing "game" which I had on a coverdisk (possibly AUI?) Which allowed you to use your own iff files and drive on them. Can't remember how much actual gameplay there was but it was when I had my A500+
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Old 08 March 2018, 14:00   #22
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Quote:
Originally Posted by chb View Post
I'd guess blitter-assisted c2p should be fast enough to do a 2x2 (or fake 1x2 like in britelite's wolf3d demo and seemingly gasega6k's demos) mode7 at half screen height at a reasonable frame rate, maybe using some self-modifying code for the texture mapper.
I have an idea on how to do this in the same fake 1x2 as in my wolf3d-demo. Basically first building an intermediate texture buffer, and then a modified version of my rotozoomer, using the blitter to generate the code for the next horizontal line while rendering the previous with the CPU. And finally use a blitter c2p to draw it on the screen. Wouldn't run at 50fps, but 25fps might be possible.

But I won't reveal any further details until I've had the time to test it out for myself
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Old 09 March 2018, 13:46   #23
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Quote:
Originally Posted by britelite View Post
Basically first building an intermediate texture buffer, and then a modified version of my rotozoomer, using the blitter to generate the code for the next horizontal line while rendering the previous with the CPU. And finally use a blitter c2p to draw it on the screen. Wouldn't run at 50fps, but 25fps might be possible.
Sounds like some seriously crazy hack! It doesn't involve some fiddling with the blitter modulos by any chance?

Quote:
But I won't reveal any further details until I've had the time to test it out for myself
I guess we have to just wait for any answer...
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Old 09 March 2018, 15:12   #24
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Interesting project, because it‘s kind of never really been done before.
If I‘d not being so busy with Inviyya I‘d loved to have a shoot at it myself..
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Old 14 March 2018, 22:58   #25
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In danger of suggesting something completely irrelevant, isn't the floor of Unreal's 3d sections eligible for this? It's a bit restricted in terms of horizontal+vertical movement, but it can move and zoom at the same time at will, so....

Last edited by vulture; 14 March 2018 at 23:26.
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Old 15 March 2018, 00:30   #26
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Quote:
Originally Posted by Coagulus View Post
I'm sure I remember a pd racing "game" which I had on a coverdisk (possibly AUI?) Which allowed you to use your own iff files and drive on them. Can't remember how much actual gameplay there was but it was when I had my A500+
Drive IFF

[ Show youtube player ]
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Old 15 March 2018, 15:52   #27
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Originally Posted by vulture View Post
In danger of suggesting something completely irrelevant, isn't the floor of Unreal's 3d sections eligible for this?
Im am very sure that these floors are made with some tricks, and that you wouldn't been able to freely navigate in them, e.g. drive backwards or doing 90 degree turns...
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Old 15 March 2018, 21:15   #28
Coagulus
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Originally Posted by capehorn View Post
Drive IFF

[ Show youtube player ]
Wow yeah I think that was it! although I did get the mag wrong.
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Old 16 March 2018, 12:29   #29
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Quote:
Originally Posted by chb View Post
Just a note: Both the "Sonic Kart" and the F-Zero clone are by gasega68k/Stephane Dallongeville, which was also active here at eab as "Stef_" (account closed unfortunately).
Gasega68k and stef are two different persons, gasega has only used the audio driver stef makes for his sgdk .
Gasega has also coded the Md wolf3D version .
[ Show youtube player ]

And don't forget the Md has a chunky display,it help a lot for that kind of effects .

If you want to know how he did do this, you can read the sega-16 tread :
http://www.sega-16.com/forum/showthr...for-Genesis-MD

Last edited by touko; 16 March 2018 at 18:53.
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Old 18 March 2018, 02:41   #30
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Originally Posted by Steril707 View Post
Im am very sure that these floors are made with some tricks, and that you wouldn't been able to freely navigate in them, e.g. drive backwards or doing 90 degree turns...
No idea whatsoever, I just noticed that you could move at both x and y axis at will and the floor perspective would respond to it, while zooming, and thought that it looked like a good candidate.
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Old 19 March 2018, 01:23   #31
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@vulture

that engine is soooo underrated, would love to see a Galaxy Force clone made with that
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Old 19 March 2018, 03:10   #32
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Tadam! Time for my traditional yearly super-long post with plenty of quotes.

Quote:
Originally Posted by dlfrsilver View Post
Brian the Lion is the best example of a game using the Mode 7 from the snes
Hair splitting: it is using an effect which looks like Mode 7. But it very likely does not implement the full functionality of that mode (which is a matrix transform for every scan line, in 8bit per pixel chunky).
I have not looked at how the effect is implemented but I would wager it is not as flexible.

Quote:
Originally Posted by Galahad/FLT View Post
The first youtube video should be doable in some form. Its highly cheated or at least, the mode 7 engine on that game knows its limitations, which is why it has no very tight turns.
The Sonic one is pretty impressive.
I think that is actually an artifact of the circuit design but both actually use the same code.
When I read the sega-16.com thread where gasega68k discussed the technique he implemented it wass clear that he is not using raster effects but real per-line perspective transform. As DanScott mentioned, that is essentially a rotozoom with different parameters per line.

Of course this is *much* sped up on the MegaDrive/Genesis by the fact that the pixels of its tiles are in chunky format and that its CPU runs 1/3rd faster than the A500's (12 MHz vs 8-ish MHz).

Quote:
Originally Posted by saimon69 View Post
I remember some copper chunky perspective demos in the past but those were having the zoom and not rotation; plus i seems to remember the limit of 8 pixels for the OCS/ECS copper; road might look pretty blocky but if we focus on playability that should be fine
Yes, that would be a good start.
Moreover Copper chunky is compatible with any lores graphic mode with up to four bitplanes so 16 colors BOBs can be drawn on top of the floor, in addition to sprites.

I would wager that this is what Virtua Karting does on the A1200 with the advantage of a faster Copper which allows 4 pixels Copper chunky.

Quote:
Originally Posted by Steril707 View Post
Would be amazing, if he could join in the discussion and explain a bit how he accomplished the outstanding work he did on the MD..
Actually it is not Stef who coded that but gasega68k. Stef is the author of a very nice SDK for the MegaDrive and he discussed extensively with gasega68k about this Mode7-like effect on the sega-16.com forums.

Quote:
Originally Posted by DanScott View Post
2) If you ever investigated how a mode 7 style floor works, it is essentially the same as a rotozoomer, except that the x/y texel positions and dx/dy are calculated slightly differently. Other than that, the inner workings of the 2 should be practically identical.
Yup. Mode 7 essentially offers a rotozoom with new parameters for each line of the screen. This is slightly more convoluted but from a practical standpoint that what it allows to achieve.

Quote:
Originally Posted by britelite View Post
I have an idea on how to do this in the same fake 1x2 as in my wolf3d-demo. Basically first building an intermediate texture buffer, and then a modified version of my rotozoomer, using the blitter to generate the code for the next horizontal line while rendering the previous with the CPU. And finally use a blitter c2p to draw it on the screen. Wouldn't run at 50fps, but 25fps might be possible.

But I won't reveal any further details until I've had the time to test it out for myself
Damn, I would love to have these details.
Is your wolf3d-demo published already?

This said, although I think some form of C2P can be used, I doubt that this would allow this effect to run in 16 colors on a non accelerated ECS machine as the C2P pass will consume a lot of the available cycles.

Since this is floor-only rendering technique I would rather try using the Copper and/or a limited number of bitplanes rather than to do a full C2P which I think is not efficient enough on 68000 kittens if you want to run an actual game on top of displaying a nice floor.

But it is good that several are thinking about it. The more kittens, the better.
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Old 19 March 2018, 09:19   #33
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Is your wolf3d-demo published already?
The demo can be found here and discussion about the rendering here
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Old 20 March 2018, 17:48   #34
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Speaking of mode7 (for Apple II)

http://www.pouet.net/prod.php?which=75630
[ Show youtube player ]
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Old 23 March 2018, 21:08   #35
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@ReadOnlyCat

Isn't MegaDrive using a 7.6Mhz 68k? I think it's MegaCD that uses a 12.5Mhz one.

@saimon69

Yes, isn't it? Many many stuff thrown around and at a very good pace as well! Definitely a good engine for an afterburner/galaxy force game!
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Old 24 March 2018, 09:15   #36
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wasnt virtual karting mode7?
nvm i see someone posted youtube of it

Last edited by nexus; 24 March 2018 at 09:20.
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Old 24 March 2018, 09:23   #37
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Originally Posted by LaBodilsen View Post
Speaking of mode7 (for Apple II)

http://www.pouet.net/prod.php?which=75630
[ Show youtube player ]
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Old 24 March 2018, 12:45   #38
touko
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@ReadOnlyCat

Isn't MegaDrive using a 7.6Mhz 68k? I think it's MegaCD that uses a 12.5Mhz one.
You're right, the stock Md's 68K is at 7.67mhz .
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Old 25 March 2018, 19:40   #39
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You're right, the stock Md's 68K is at 7.67mhz .
So that leaves the advantage of chunky mode..
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Old 27 March 2018, 10:05   #40
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So that leaves the advantage of chunky mode..
Yes it's always better than a complex planar format for mode 7
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