Exhibit fences 1 tile away from map edges can cause crashes

[Jay]

If an exhibit fence is 1 tile away from the edge of a map, MM and CC will eventually crash. Most exhibit fences are configured to deteriorate and break. When these exhibit fences deteriorate or break, MM and CC will add the task of fixing them to its internal work queue. When a maintenance worker becomes available, MM and CC try to figure out a way to get the maintenance worker to the next task to do. If that next task is to fix a fence and if that fence is 1 tile away from the edge of a map, MM and CC will crash. So exhibit fences should never be 1 tile away from the edge of a map. I did not test in DD or the orginal ZT to see if those also crash.

The image shows examples of exhibit fence placement. Position A is 1 tile away from the edge of the map. So that position should not be used, since it will eventually cause MM and CC to crash. Positions B, C, and D are okay to use because they are more than 1 tile away from the edge of the map. Note that the zoo wall positions do not matter relating to this type of crash. Positions A and D are against zoo walls, but position A will eventually cause a crash while position D will not. Exhibits can be built so that the existing zoo walls are used to enclose the exhibit. So the exhibit fences in positions A and D are not needed because zoo walls 1 and 3 would be used to enclose the exhibit. Although zoo walls 1 and 2 are 1 tile away from the edge of the map, they will not cause a crash because zoo walls do not deteriorate or break, while exhibit fences in the same positions such as position A will eventually cause a crash.

If you have a zoo where there are deteriorated or broken fences 1 tile away from the edge of a map, you might be able to delete them before ZT attempts to assign a maintenance worker to fix one. Load the zoo, immediately pause ZT, delete all exhibit fences that are 1 tile away from the edge of a map, save the zoo, and load the zoo again. It is important to save the zoo and load it again because just deleting a deteriorated or broken fence does not remove fixing it from ZT's work queue. Sometimes it is difficult to pause ZT immediately, since there is sometimes a delay between clicking the pause button and ZT actually pausing. So you might need to make multiple attempts at loading the zoo and immediately pausing ZT.

For mapmakers, the above mentioned crash might influence where you put zoo walls. In the image, zoo wall 4 is at the edge of the map. That should never be done because MM and CC will crash when attempting to delete that zoo wall as part of editing the map. The original ZT did not have that problem. There are two types of positions of zoo walls that are 1 tile away from the edge of the map. Zoo walls 5 and 1 are 1 tile away from the edge of the map and are on the side of the grid line closest to the edge of the map. If you use this type of position in your map, you should warn others that use the map not to put exhibit fences against the zoo walls because that will cause an eventual crash. Zoo walls 6 and 2 are also 1 tile away from the edge of the map but are on the side of the grid line furthest from the edge of the map. This type of position will not cause a crash. With this type of position, exhibit fences cannot be placed against the zoo walls. Position C shows the closest that the entire exhibit fence can be from such a zoo wall. But it is possible to have the edge of an exhibit fence touching a zoo wall, allowing the zoo wall to be part of the enclosure. That does not cause a crash. Zoo Walls 7 and 3 are 2 tiles away from the edge of the map and are on the side of the grid line closest to the edge of the map. That is the closest a zoo wall can be to the edge of the map while allowing exhibit fences to be against it safely. The positions of zoo walls 5 and 6 are also okay as long as exhibit fences are not positioned against them, with zoo wall 5 requiring care by those making zoos on the map.