Platforms in Marathon are quite versatile, allowing a tremendous number of tricks and aesthetic variations. The doors on Acme Station are an example of one aesthetic detail possible with platforms.

On Acme, the retracting doors are a thematic necessity, built to give the impression of a thin floor. If these doors had been simple, full length retracting-into-floor-doors, the player would wonder why he couldn't see them extend under the station.

Four Polygons make up these retracting doors.

Our plan:

1. First we draw the geometry.
2. We set all the platform data.
3. Then we texture it in visual mode.
4. We set the switch to activate the door.

2. We set up the Platform dialogs like this. You can use the 'base-on' to set up the rest of the plats quickly, changing only the relevant parts. In our example, the relevant parts are the 'delay' and 'max height'.

In this case, we've kept the speed of the platforms the same, and set the heights and delays so that when the highest platform reaches it's neighbor, the neighbor's delay has elapsed and it retracts as well. (In the picture on the left, I moved the plat info around to make it fit better.)

3. We'll go in and texture everything now. The Acme doors appear to retract because of the alignment of the floor and side textures. Since floor textures cannot be rotated, all the doors on Acme have to be facing east-west (right to left). The textures on the floor were carefully lined up with the textures on the door so that their surfaces look seamless as the doors open.

In general, lining up floor textures makes an area look more realistic and visually appealing.

4. Setting the switch is pretty straightforward, but we need to keep some things in mind. What happens if someone walks up to the switch and hits it repeatedly, will the door get messed up? What happens if someone is standing on the door when it goes back up?

Ok, we've set the switch to activate the platform that de-activates last. That way, vidding the switch won't do anything.

Our platforms de-activate at each level, so it would be pretty hard for someone to get stuck in them as they came back up. (I spent a few hours trying to do this by myself, and couldn't.) In cooperative play, it would be possible for someone to get stuck when a so-called friend hit the switch. Avoiding this is nearly impossible. I wouldn't worry about it too much. It's pretty funny to see your friend stuck in a door.