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 Post subject: Re: Literal recreation
PostPosted: Wed Nov 08, 2017 9:27 am 
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In theory, an HDMI famiclone could emulate NTSC modulation artifact emulation in the same way that Nestopia does. But this video walkthrough of the AVS's video options doesn't show such a filter.


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 Post subject: Re: Literal recreation
PostPosted: Wed Nov 08, 2017 9:48 am 
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But then you can just as well use Nestopia (or other emulators that support NTSC filtering) for testing and spend no money at all, if you're only interested in the artifacts because you're an artist.

I personally would love if these new consoles supported accurate NTSC simulation, I simply love those artifacts.


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 Post subject: Re: Literal recreation
PostPosted: Wed Nov 08, 2017 12:47 pm 
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FrankenGraphics wrote:
rainwarrior wrote:
The NTSC rendering has a repeating colour-error emphasis every 3rd pixel of a scanline

Would i be able to properly view how this looks on an AVS on a HDTV in Europe? I've been thinking about treating myself with one (to be able to play N.American releases properly, but also to be able to test things like these out).

Someone else might correct me if I'm wrong but I think the artifacts come entirely from the NES' signal generator, it's not really the TV. (Though the TV obviously makes its own impact on things.)

Lots of NES emulators have an NTSC simulator in them that do a very adequate job, IMO. I usually use this build of Blargg's filter demo to preview this kind of thing when I'm working with images instead of emulators. (A lot of emulators that have it are just using Blargg's implementation anyway.)

BTW the diagonal "volumetric lighting" spilling from the windows will be heavily affected by the artifacts, and will definitely shimmer as they move, but by coincidence the artifacts are at the same diagonal angle, so you might actually like this effect.

FrankenGraphics wrote:
Vertical progression + vertical scrolling, and vertical progression + vertically static screens will provide very different opportunities to present platforming challenges, enemy behavior and so on.

Of course, but I wasn't stating a preference. I just missed the point of reference to suggest one or the other.

FrankenGraphics wrote:
Quote:
Your estimates for tile permuations sounded like you only meant for 1 dimension of parallax, not 2. (Incidentally, using sprites could make both feasible at once?)

This is also correct, i intended it for one dimension. Plus the way i'm using different attributes in the forest horizon should prohibit vertical parallax... I'm having a hard time wrapping my head around how sprites would help with 2-minensional parallax, though?

Most of the strip could just be one colour 8x8 tiles, and then sprites for the detailed parts at the horizon and top of the screen. You'd only need one copy of the tiles because the sprites could move up/down/left/right as needed, and the coarse background tiles would not need to be updated frequently (could probably get away with changing only one tile at a time as the horizon moves).

The left/right motion would need some way to cut off the sprites behind the background, but there's multiple ways to accomplish that. (e.g. placing the sprites behind an opaque background, or if you can spare a third sprite on the scanline you can use a blocking background-priority sprite to hide it, or you could use horizontal tile permutations for the cutoff and only shift the sprites vertically.)


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 Post subject: Re: Literal recreation
PostPosted: Wed Nov 08, 2017 1:33 pm 
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Aha, so the background would only be lines of colour, and the sprites would provide the detail.
I might change this, but right now, the wall is completely opaque (the bg colour is the bright sky one, and the black is shared by three subpalettes), so that's a start.

I'll keep this idea in the options drawer for posterity*, thanks!


*(it'll take some time before we can actually work on this properly because we already have one game to finish).

Another (simpler, less impressive) option is to simply center the camera so nothing outside is shown when scrolling vertically.

If blarggs' tool is accurately showing these artifacts, i don't think the still image looks that bad? I'm a bit pleased it seems to smooth out the gradient a bit.
Attachment:
filtered.bmp
filtered.bmp [ 1.03 MiB | Viewed 255 times ]




One last thing is in the way of making this scene work as a vertically scrolling room, and it's the 2D concaveness of the cross-section perspective (type B). Type A solves this but makes everything look oddly tilted. Two other options are stretching the vertical concaveness out over 2 screens height instead of one, or making the shape of the tower concave in only one dimension, which weakens the effect by some, but works endlessly.
Attachment:
types.bmp
types.bmp [ 4.12 KiB | Viewed 255 times ]


rainwarrior wrote:
BTW the diagonal "volumetric lighting" spilling from the windows will be heavily affected by the artifacts, and will definitely shimmer as they move, but by coincidence the artifacts are at the same diagonal angle, so you might actually like this effect.
That might actually be neat! Unlike the shimmer you can see (but which i've sort of accepted) in the first outdoors mockup in the lower mist and mountain base.

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 Post subject: Re: Literal recreation
PostPosted: Wed Nov 08, 2017 11:51 pm 
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FrankenGraphics wrote:
If blarggs' tool is accurately showing these artifacts, i don't think the still image looks that bad? I'm a bit pleased it seems to smooth out the gradient a bit.
Attachment:
The attachment filtered.bmp is no longer available

Well, like I mentioned, those diagonal light shapes are strongly affected. You can see a lot of diagonal groups where it's discoloured, but it complements the texture nicely there, esp. because the angle of the artifacts is the same as that diagonal direction anyway.

The regular dither patterns above the flat stones, though, you can see how the varying emphasis the the regular shapes there produces strange grouping patterns. This will shimmer and stand out very strongly as soon as you start to scroll as well. (Especially note how about just below the middle of the image, there's lines of 4 pixels that are emphasized. That will change with scrolling, dimming and brightening every 3 pixels.)

If you want to try it out without using an emulator, you could make 3 images with the tool, each with 1 more column of pixels on it to adust the phase of the artifacts. (Note: the phase changes only when you scroll-- when standing in one place it will not shimmer, so it's going to be driven by player movement, rather than being a continual animating thing like this GIF.)
Attachment:
tower3_shimmer.gif
tower3_shimmer.gif [ 368.48 KiB | Viewed 211 times ]


It's a subtle problem, though, not necessarily something you have to worry about. Unless you cover big parts of the screen with blocks of checkerboard, I think it's reasonable to just ignore, even.

FrankenGraphics wrote:
One last thing is in the way of making this scene work as a vertically scrolling room, and it's the 2D concaveness of the cross-section perspective (type B). Type A solves this but makes everything look oddly tilted. Two other options are stretching the vertical concaveness out over 2 screens height instead of one, or making the shape of the tower concave in only one dimension, which weakens the effect by some, but works endlessly.

Honestly, I think what we're looking at here is too subtle to communicate a curved back wall, and the prominent flat foreground blocks strongly contradict it anyway. The parallaxing hanging chain is a nice touch (but doesn't really have to do with the curve). The tilted window feels weird to me without already trying hard to imagine that it's curved, and similarly the curved dark background bricks feel more like random variation / uneven stonework than a suggestion of curve.

I like the attempt, but the effect isn't strong enough to unambiguously say "curved tower" to my brain. At the same time, though, I probably wouldn't want to spend as many extra tiles as it would take to imply that more strongly anyway-- as a square tower it already looks great. (...and I probably wouldn't even think twice anyway if there was an external long shot view showing that it was really curved from the outside. A square inside would be an acceptable fiction in this context?)


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 Post subject: Re: Literal recreation
PostPosted: Thu Nov 09, 2017 5:14 am 
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:shock: I really like that constant shimmer in the light rays in your demonstration; it feels alive. It makes me wish i could achieve that constantly without shaking the structure. :) It has fantasia's night on bald mountain interpretation all over it (which left a huge impression on me as a kid). Then again, it might be too attention grabbing if it did cycle all the time.

I guess the misty highlights along the floor could be tamed just like the sky gradient, but again at the expense of hogging a few more tiles. Or i could come up with a more stylized option for about the same number of tiles.

Quote:
Honestly, I think what we're looking at here is too subtle to communicate a curved back wall,
I see. It might be that my intention and preknowledge has got me fooled. I'll have to think about that. I'm pretty sure i can do a better job, but i think i'll let this scene rest for a while, and see what comes naturally later on.

This is all very helpful, i really appreciate it.

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 Post subject: Re: Literal recreation
PostPosted: Thu Nov 09, 2017 8:54 am 
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Normally, the NES PPU skips one dot before every second video field in order to make the dot crawl pattern appear stable. But it doesn't skip the dot if rendering is turned off. So to get that shimmering on an NES, you could leave rendering turned off for the first scanline for two consecutive frames out of every eight, ten. This may be tricky to time and may cause (invisible) flicker artifacts in the top overscan, I'll admit.


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 Post subject: Re: Literal recreation
PostPosted: Thu Nov 09, 2017 3:47 pm 
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FrankenGraphics wrote:
One last thing is in the way of making this scene work as a vertically scrolling room, and it's the 2D concaveness of the cross-section perspective (type B). Type A solves this but makes everything look oddly tilted. Two other options are stretching the vertical concaveness out over 2 screens height instead of one, or making the shape of the tower concave in only one dimension, which weakens the effect by some, but works endlessly.


I bet if you're scrolling up, mostly, the inverse of type A could work because your eyes are focused more on the top of the screen, where the background would appear to be in the correct perspective.

Attachment:
TypeA.png
TypeA.png [ 366 Bytes | Viewed 138 times ]


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