again about the parallax-scrolling issue

[Tatsujin]

last time when i emulated the US magical chase in Magic Engine, where you can switch on/off the BG or sprite layers, i've discovered something strange. as we all learned, the pc engine is incapable of displaying a second BG-layer, most useful to create real parallax-scrolling as we know it well from the Mega drive etc.
but, parallax scrolling can be simulated by using huge sprite-fields or cheaply by some sync-scrolling (but which doesn't allowes to cross an object over the other -> scanline overlapping).

but when i swiched off the sprite layer in the fist stage of magical chase, the faster scrolling foreground still was there (us magical chase: wooden promenade; jap magical chase: tetris like BG). and it even can be scrolled in horizontal as well vertical directions.

so now the question is, how did they fool the pc hardware to be able to do that effect?
and furthermore, why other developers rarely didn't take advantage of that "trick"?

while i was checking a lot of games in ME to prove how they did the parallax, they always used the sprite-trick, except of magical chase.


i remember we talked about that before (with Bonknuts etc), but iirc in that discussion we came on the point that this must be a huge sprite drawed over the whole screen, but which isn't the case (unfortunately can't find the old thread)

[Bonknuts]

That fat bar is just another section of the BG layer/map. You can overlap any BG areas right down to a single scanline, you just can't see through them so to speak. The farthest BG layer is just palette updates that make it look like the clouds and the wall are separated. The foreground BG layer(bar) is an hsync scroll. At that point in the game, the code/program switches the BG position to another area, then at the end of the bar it switches back. Very easy to do and Magical Chase reuses the same technique on the flying ship level. The limitation of that effect is that bar has be from edge to edge of the screen (in most cases). The PCE can do split screen scrolling down to ever scanline and that bar is pretty much the same effect.

[Tatsujin]

oh thanx a lot mal, for re-freshing my brain^^

so as far as i understand, the use of hsync scroll allows you to place a straight object (aligned on the same scanline) which then you can move around in any desired direction (h & v) on the screen, even there already is a fixed BG?
and the main differences to a real two layer scrolling is that, that you can't create an object in any kind of shape (means not aligned on the same scan line)  and let it scroll the same way as for the hsync rules above?

an other question you might answer to me, does the c64 have a 2nd or more BG layers?

[nodtveidt]

The C64 only has one BG layer as well.

[Tatsujin]

ok..so they did games like flimbos quest?