More on sectors:  water tanks
rotating doors || water tanks 

pic1: Duke is facing the doorway to the sector directly over top the water tank. pic2: Here we see Duke floating in the sector over the water tank, looking back toward the doorway he's in front of in pic1. pic3: Duke submerges and is now in the water tank and is able to view the lower level through the windows of the tank.

Normally, the above water and below water sectors are in different locations, with the same size and shape but this "water tank trick" is done with the "above the water/below the water" effect sectors are in the same location. This allows the player to view the area outside the lower sector. Use lotag 1 sector effector x,7 for the above sector, and lotag 2 sector effector x,7 for the lower sector. If you bring the walls of both sectors close together, the engine will render this trick as if it were a normal water sector effect. That's what we're trying to do with this trick; make the sectors very close in size and shape, yet on different levels on the vertical plane.

 More on sectors:  water tanks
rotating doors || water tanks 

Pictured below is a 2D of the water tank sectors.
The walls of the upper level are so close to those of the lower level that they do not show up well in the screen capture. The upper level walls are most noticeable on the left where I've placed a wall crack. You can see the upper level's wall (white line) just in front of the hole in the wall's lower sectors (red line). The upper and lower levels' walls are so close that, in the screen shots, they look like only one wall. The walls need to be close together, yet not touch. You need to do this in order to have the "water tank trick" work properly.

2D of water tank



 More on sectors:  water tanks
rotating doors || water tanks 
In this picture, you can see the proximity of the above sector's wall to the lower sector's wall. The white line is the wall of the sector above (the sector which is above the water in the tank) and the pink line is the window in the sector below (in the water tank). I started this portion of the map by making the entire level below but it doesn't matter which level you build first, as long as both levels are higher/lower than each other on the vertical plane. If you understand this, you shouldn't have too many problems building this effect. For example, let's assume you've done what I did and started with the level below, built the sloped sectors leading up, and then made the sector over top of the tank. You don't have to start the sector above with the walls close to the ones below. Just use an appropriate sized grid to make the sector above. Once you've done that, turn off the grid locking and pull each of the vertices of the above sector as close as possible to each of the vertices of the sector below without overlapping or going outside of the vertices below. I didn't block the windows of the lower sector until I was finished with this effect. You will still need to get into the sector to place the sector tags and the sector effector. Once you have the sector over top, it's difficult to get the tags placed in 2D; you will have to place the effectors in 3D mode. Notice the proximity of the wall of the upper sector to the wall of the lower sector. (window on the east side of water tank shown in 2D above)
 More on sectors:  water tanks
rotating doors || water tanks 


2D of water tank In 3D mode, get into the lower sector (inside the water tank), point your cursor at the floor and press the S key. If what ever appears before you isn't the sector effector sprite, then make it that sprite. Now, with the cursor on that sprite, hold down the ' key and press t and give this sprite the lotag 7. With the cursor still on that sprite, hold down the ' key and press h give this sprite a unique hitag x (your choice).
We still have to give this under water sector its lotag. Place the cursor on the floor, hold down the ' key and press t and give this sector a lotag of  2. Repeat this procedure for over the tank, giving the sector above a lotag of 1.


We're almost done. Now that we've got a sector effector sprite in both the upper and lower sectors, and have given the upper and lower sectors their appropriate sector tags, there's one more thing to do: In 2D mode, with the grid locking on, make sure that the sector effector sprite (x, 7) in the lower sector (inside the water tank) and the sector effector sprite (x, 7) in the above sector (the above water sector) are both in the same location. If you look at the picture directly above, you'll see that it looks like there is only one sector effector sprite. However, there is one for both sectors. They only look like they are in the same spot in 2D.


rotating doors || water tanks