The illusion of scrolling in AGI

[lance.ewing]

I was just wondering over the past day or so whether anyone has tried to create the illusion of a scrolling room within AGI. I was thinking that maybe having a series of AGI pictures that are different frames within the scrollable scene, and as ego walks a certain way across the screen that it animates a scrolling background by loading some pictures in quick succession. You'd obviously be sacrificing valuable pictures but for a smaller game maybe it would be okay. I'm not sure if the picture load and display would be fast enough or whether it would look a bit jerky. Any thoughts?

Another thing I've thought about more than once is that the original Maniac Mansion game was the same resolution as AGI. Wouldn't it be cool to try to come up with an interface in AGI that looks similar to the one used in Maniac Mansion, where the bottom part of the screen has the words and inventory items and the top part is the picture. We'd basically throw away the built in prompt and message box capability in AGI and try to simulate the MM alternative, which I quite liked.

[MusicallyInspired]

I would say a better idea would be to make a single background and make a series of sprites that move while the ego stays still and animates. Similar to how the hallways at ScumSoft work in SQ3. Of course it would have to be extremely simple-looking and it would have to have a whole whack of sprites to fill in the details.

[lance.ewing]

Yeah, I've thought about that as well. It would probably take quite a lot of VIEWs to do something like that.

The original Maniac Mansion came out for the Commodore 64 and the first version for the PC used pretty much the same data files. One side effect of this is that the graphics for the screens were all based around a C64 character set and screen map. So the screens were built by reusing the same small multi-colour 4x8 bit maps. We could almost do the same thing with VIEWs, i.e. build up the whole screen by placing various VIEW cells across the screen to make up the background.

[Eigen]

I haven't used AGI in ages, but wasn't there a view (object) limit for each room? 16? Or maybe I'm remembering something wrong ..

[lance.ewing]

Yeah, I'm sure there is a limit on the number of views on the screen. I don't think that having animated views would give us what we want, unless the screen was very basic. I recall that there was a way of adding a view on top of a picture in such a way that it becomes part of the picture rather than being a managed view. I think it was called add.to.pic. Yeah, I just did a google for it and found this:

Code: [Select]

add.to.pic(a,b,c,d,e,f,g), add.to.pic.v(a,b,c,d,e,f,g)

A picture of a VIEW resource is added to the background as its component. Typically, this is used to add small complicated details which would require too many PICTURE resource commands to draw.
Parameters are:
a (va): number of the VIEW resource;
b (vb): loop number;
c (vc): cel number;
d (vd): x coordinate;
e (ve): y coordinate;
f (vf): priority;
g (vg): margin.
If margin is 0, 1, 2, or 3, the base of the cel is surrounded with a rectangle of the corresponding priority. If margin > 4, this extra margin is not shown.
So in theory with the above command you could build up a whole picture by loading different views and placing cells on the picture at various positions. Part of me wants to try to write something to convert a Maniac Mansion picture to AGI resulting in a number of views cells and a LOGIC to place them in the appropriate positions. Hmmm, thinking about it though, maybe the generated LOGIC script would be too big. It would be something like 40x20x8 bytes.

[Raf]

I've done so -- more or less -- once in a long-since cut intro for NF. It was basically scrolling down a castle. That was veeeery easy to do (although complicated drawing-wise cause I suck at animations). It was just a single view that scrolled down. The whole thing was limited to a tiny screen to do so.

Another possibility's something Cloudee's come up for in SCI and I have yet to implement in AGI. That's for scrolling in all 4 directions (giving the impression of a round world), so it should be possible to adapt to just horizontally or just vertically.

That possibility is hiding the ego view, centering a dummy ego on the screen (or placing it at an offset of the center, or wherever, but it's principally fixed in place). You got some objects on the screen, like some scenery, which moves in accordance to ego's position (moves to the front if ego moves up, moves to the back if ego walks down, moves to the right if ego walks left, and to the left if ego walks right). I guess the least resource-hungry would be to make a couple of background strips that scroll and loop (Hanna Barbera-style). You can even do parrallex scrolling that way. You can still move in the most important objects, like a wall to jump over or a pit to fall into, too. I wouldn't create a Bullet Hell shooter this way, though (max. of 16 objects in one room. 1 hidden player, 1 replacement ego, and 1 enemy leaves room for a whoopin' total of 13 more bullets. Not exactly Bullet Hell )

So yeah, depending on what you're trying to do, it's possible to do. If you need more technical details from the SCI version, you'll have to ask Cloudee. What I explained is just what I understood from it, but haven't gotten around to doing it myself yet, so who knows... maybe it'll blow your neighbour's kitchen up if you try it!

[lance.ewing]

Something a bit like the scrolling effect in Maniac Mansion and Zak McKraken where the actor that you move (what we call ego for Sierra games) starts walking across the screen and when they reach a particular part of the screen, the background starts moving while they remain stationary (although the illusion is that they are still walking through the room). And then when they reach another part of the screen, the background stops scrolling and the actor starts moving from the center to the edge of the screen. I'm sure you've seen what I've described. The rooms are usually about two screens wide and the movement through the central part of the room makes the background scroll.

Cloudee has already pointed me in the direction of what you two had worked on so far, but I must admit that I've been too busy working on PICEDIT to have a good look yet.