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Reverse-engineering raster effects

#1 User is offline Sonic 65 

Posted 26 June 2018 - 05:58 PM

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(I made this topic to ask about an effect in a specific game, but if anyone else wants they can piggyback and use this thread to ask about others.)

Does anyone know exactly how Dracula X on SNES gets that awesome fire effect on the first stage? Badly upscaled image:

Posted Image

It seems to be applying raster animation to a static "fire image" (basically, selectively repeating or omitting vertical strips), in addition to additive blending. But how, exactly?

I'm trying to replicate the effect for a level in my game (on PC, but sprite-based at 240p). This is the closest I've got so far (background of the stage removed):

Posted Image

Not nearly as smooth or cool-looking!

And the code for how I'm producing the above:

double stripY = 0;

for (int i = 0; i < flameHeight; i++) {
    double pct = i / (double)flameHeight;
    double time = counter / 8.0;

    double inc = Math.Cos(pct * 3.14159 * 8 + time * 0.5);
    inc = (1.0 + inc);

    stripY += inc;

    // render horizontal strip at stripY, advance one line down
}


...where the counter increments every frame.

I could step through an emulator and figure out the effect myself, but it's been years (going on half a decade??) since I've looked at any assembly, and I have zero experience with the SNES hardware. So I was wondering if anyone here knew about this.

Thanks for your time!
This post has been edited by Sonic 65: 26 June 2018 - 06:01 PM

#2 User is offline Overlord 

Posted 27 June 2018 - 12:17 PM

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Silly question, but are you sure it's not just a form of Mode 7 sprite manipulation?

#3 User is offline Sonic 65 

Posted 29 June 2018 - 09:12 PM

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I asked over at SNESdev: https://forums.nesde...hp?f=12&t=17484 -- a guy gave me a tip and it looks great now.

Posted Image

No Mode 7, just good old fashioned raster effects. It could've been done on the MD (in fact, I wonder if it was somewhere...)

(The guy inside the robot suit is, of course, Dustin Wyatt. Or at least you can pretend he is.)
This post has been edited by Sonic 65: 29 June 2018 - 09:37 PM

#4 User is offline 360 

Posted 29 June 2018 - 11:01 PM

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The new fire effect looks visually stunning - even beyond the assumed capability of the hardware as it looks that good - and your game looks amazing. Excellent work.

#5 User is offline Sonic 65 

Posted 30 June 2018 - 12:59 AM

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Thanks man!! You can follow the game here: https://twitter.com/SteelAssault

We released a video about this time last year, but development's been slower since then (mostly focusing on assets). But as you can see, it's finally picking up again!

#6 User is offline Ritz 

Posted 30 June 2018 - 06:12 PM

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That's... Actually one of the coolest games I've ever seen? Holy shit. That's like 2½ stars on culture.vg. How many artists are working on this?

Glad to see you're still around too, it's been a while!

#7 User is offline Sonic 65 

Posted 01 July 2018 - 12:18 AM

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One consistent sprite artist, and a revolving door of background artists -- 2 artists at any given time, and 4 overall. (5 if you count the original artist, when it was still an 8-bit game. His work has since found a home in Cyber Shadow, and I have to say, that game puts his assets to much better use than I ever did.) Surprisingly, it hasn't been too bad keeping things cohesive; you can 100% notice the stylistic differences if you place the art for different areas side by side, but when playing the game it'll feel seamless.

We also recently hired a composer. I was originally handling all the music myself, but it got overwhelming (the OST is over 20 tracks) and I wasn't satisfied enough with some songs. The DC theme in the above video has since been replaced with a collaborative track I like way more, for example.

And yeah, it feels like an entire age ago when I was really active on these boards! I have a lot of nostalgia for the old Sonic games, and this forum was a key part of my early teen years, but I don't have much interest in the franchise anymore (barring a complete reinvention with hand-drawn HD 2D art, or someone finally finding a Sonic 1 beta after 20 years of this community searching). It's hard to believe I was 15 when I made DWEA...

#8 User is offline Felik 

Posted 01 July 2018 - 07:42 AM

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The steel rope gimmick is pretty sweet. Glad you upgraded graphics.
Character seems to run really slow though

#9 User is offline Hukos 

Posted 04 July 2018 - 12:21 PM

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View PostSonic 65, on 29 June 2018 - 09:12 PM, said:

I asked over at SNESdev: https://forums.nesde...hp?f=12&t=17484 -- a guy gave me a tip and it looks great now.

Posted Image

No Mode 7, just good old fashioned raster effects. It could've been done on the MD (in fact, I wonder if it was somewhere...)

(The guy inside the robot suit is, of course, Dustin Wyatt. Or at least you can pretend he is.)


It reminds me of the Gorgon background from Thunder Force III.

https://www.youtube....h?v=P6gMCm1XcQg

Obviously not as detailed as yours, but it looks like a raster effect to me.

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