The nice water reflection effect with copper?

[ImmortalA1000]

It has been so long since I even thought about this, let alone knew how it was done technically, I found myself googling for info on a hunch! Basically imagine you had a 64 color EHB sunset pic of an iconic building like say the Taj Mahal with the water in front of it and in the area where the water is you would have a shimmering effect and the image of the building translucent etc (copperlist palette change seems obvious on that line to max out colours on screen)

Now as I understand it the copper can be used to mirror parts of the screen so I am guessing that is how you get the basic images from above the water line right? Of course if you skip the lines duplicated 2:1 you get the right sort of image to be reflected I assume. Can the copper be used to stretch scanlines in hardware horizontally to give a perspective effect though?

Then I read in Fire & Ice the ripple was done by playing with the pixel scroll registers for smooth scrolling scanline by scanline and that sounds the most straight forward way to do it to me. Other ways?

I couldn't even remember which games had the water effect, I remember there was some sort of futuristic game arcade adventure escape type thing possibly by Krysalis Software and you were escaping some building and as you walked around the screen left right over water areas it was all reflected. Anyone remember that game? I only remember reading about it in a review that made special mention of it but as it wasn't the kind of game I wanted on Amiga for my money I never got it so that's my only memory sadly.

edit:looked at Prison by Krisalis....it's not the screenshots I remember from the game I am talking about so ignore that comment unless Krisalis did another Amiga game that fits the walking round left/right on flip screen arcade adventure type thing not called Prison

[WayneK]

You've pretty much covered how it's done exactly
The reflection is done using modulo, usually according to a table for a 'ripple' effect, to show specific lines of the image you want reflected. The movement can be accentuated by also using h/w scrolling to shift the reflected lines horizontally according to a sinelist.
Without h/w scroll tricks + strict timing a perspective effect isn't really possible (unless you use a bunch of extra precalculated graphics), it's usually enough to do as described above.

[ImmortalA1000]

Thanks for the update

Annoying that I used to know all this stuff and which demos did what tricks the best back then.