Unreachable entity test

[elexis]

A terrain tile is considered impassable if the slope is too steep.

On many atlas maps there are trees and the like on impassable tiles. Then units that try to gather the trees will forever try to reach the entities but fail to do so.

It should be possible to discover unreachable trees when the map is loading and throw a warning message.

So we don't have to test manually anymore to find those unreachable trees and we can remove them easily by the reported entity ID.

[Stan]

This functionality could be implemented on save in Atlas instead of on every game check unless you meant it for random maps ? If it's run before every map it ought to be optional for performance concerns.

I'm not sure on how to to convert PMP files to heightmap to perform those checks though.

[elexis]

Thanks for the uploads.

The tree at the map border is on the skirmish map Persian Highlands (4), so not a rmgen bug, but a good example for this ticket. Atlas could warn if it doesn't make it impossible to place gatherable resources outside of the map territory.

[elexis]

In 20802:

Fix a resource collision in rP17903 in the Lions Den and in rP12747/rP12654/rP12545 in the Unknown maps, refs #4902.

[FeXoR]

In case of the map border: Trees (or actually all entities) placed inside the map border could be replaced by the corresponding actors - in Atlas on save (informing the user with a waring or something) and on random maps at map export.

[wraitii]

We could easily expose an 'IsTargetReachable' function after ​Phab:D1835 which would make this a bit less of a problem as entities could discard unreachable resources.