[StephenUK]

I've been playing through Rocket Knight Adventures today, and upon playing Stage 3, I remembered the mirror effect the lava uses as shown below.



My question is, does anyone know how this effect is achieved, as it certainly looks impressive and would be useful for some neat water effects? I've been trying to think how it was done, but I'm at a loss, so I'm pretty curious if any of the more technically minded members could throw out a few possibilities, or may even know the way it is actually done.

EDIT: I realise this isn't technically a Sonic related question and I have posted it in the Sonic forum, but I think this is something that could be implemented into future hacks and could be a nice addition. However, mods feel free to move it to General Gaming if you feel the need to.

This post has been edited by StephenUK: 24 March 2011 - 04:11 PM

[Andlabs]

I'm guessing sprite flipping + palette line tricks... maybe alt tiles? I do have some large amount of RKA code disassembled but never looked through it...

[nineko]

Castlevania: Bloodlines also has some neat effects: http://www.youtube.com/watch?v=oDrLpD-RB_I (go to 3:10).

edit: hm, they're both Konami games, it can't be a coincidence.

This post has been edited by nineko: 24 March 2011 - 04:33 PM

[StephenUK]

I'm guessing sprite flipping + palette line tricks... maybe alt tiles? I do have some large amount of RKA code disassembled but never looked through it...

I was thinking about flipping at first, but the way the lava rises, it seems to work on a per scanline basis, and as far as I know that wouldn't be possible with ordinary flipping. The only thing I could think of is that it uses a routine to redraw X amount of scanlines from the bottom up instead of the top down to produce a duplicate effect, and then using an effect similar to the Sonic water palette effect to switch the palette on the scanlines. This is merely speculation though, as far as the VDP and HBlank / VBlank stuff goes, I'm not very knowledgable, I just know the basics.

This post has been edited by StephenUK: 25 March 2011 - 08:40 AM

[nineko]

Oh, I was sure I read something about that on spritesmind:
http://gendev.spritesmind.net/forum/viewtopic.php?t=564

I am getting rusty, back in the day I would have posted this link sooner, instead of taking 18 minutes to remember it

This post has been edited by nineko: 24 March 2011 - 04:36 PM

[Sik]

Yeah, it's essentially just changing the vertical scrolling mid-screen and putting two copies of each sprite... It's even easier than the water raster effect in Sonic games as only one value needs to be written, in fact. There isn't much more to it.

[Shadow Hog]

I couldn't help on the technical side, but seeing that image makes me wonder:

...since when was lava reflective?

[Caitlin]

Since possums would walk on two feet, put on armour, grab a sword and fight for world conquest (I think?).

[JaxTH]

Because it's lava in an Ice Cavern?

[Jaseman]

Good lord, that looks like Lava Reef Zone.