Reverse-engineering raster effects

(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:



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):



Not nearly as smooth or cool-looking!

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

Code (Text):

1.  
2. double stripY = 0;
3.  
4. for (int i = 0; i < flameHeight; i++) {
5.     double pct = i / (double)flameHeight;
6.     double time = counter / 8.0;
7.  
8.     double inc = Math.Cos(pct * 3.14159 * 8 + time * 0.5);
9.     inc = (1.0 + inc);
10.  
11.     stripY += inc;
12.  
13.     // render horizontal strip at stripY, advance one line down
14. }
15.  

...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!

 

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



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.)

 

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!

 

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...