We have not seen a use case where non-square / rectangle terrain made as much sense that we would even consider adding the overheads required to support it (This is the reason why Path Painter tells you to let us know your use case, in case you do really need it). In other words, it has no pros, only cons (to the best of our knowledge).
It isn't obvious about non-square Unity terrains, but they are essentially square terrains that are squashed. So if you make a square terrain, paint on it and then squash it on one side, you get the same result.
(You can actually try this as a workaround for Path Painter:
- Make your terrain square by changing its Terrain Width/Terrain Height under Terrain Settings of the Terrain component.
- Paint on it with Path Painter
- Then change Terrain Width/Terrain Height to their original values
(Your painting will be squashed of course))
This is where the overheads would come into the picture, because Path Painter would have to look out for and account for the distortion. The best we can tell, less than 0.045% of Path Painter users even considered using non-square terrains and most of them decided against it once they learned how they really work. As of now it doesn't make sense to add the overhead for all users with these numbers. Unity recently decided to add the overhead to its now GPU accelerated tools, but this is what you got when you painted on a non-square terrain not long ago:
Simple terrain painting, like the built-in ones, are not too troublesome over these squashed terrains, but Path Painter magic can be more taxing, so we want to avoid any unnecessary overheads. So far it seems like supporting non-square terrains would be only lose, no win.
Since edges of terrains are generally hidden from players by water, mountains or other visual obstructions, we don't know of a case where rectangle terrains are a better option. Creating your rectangle play area on a square terrain tile uses the same resources and it can actually provide better performance (depending on the kind of culling and other optimisations used). To use less resources one can create the rectangle by using smaller square terrain tiles.
The squashed nature of non-square terrains is visible in wireframe shading modes (for more info on Scene view control bar and Shading Modes, see this Unity Documentation).
So the pros and cons of non-square terrains look something like below.
None that we are currently aware of
- It's not actually good for performance. In fact, due to its squashed nature it's more data dense on one axis with virtually no benefit, since the other axis is your detail limiting factor.
- It feels like this inconsistency could lead to unpleasant surprises and troubles down the line, and you could get in more and more trouble with it over time, because many things could have trouble with it. If at one point that turns out to be something essential to your project, you may have to recreate your terrain.
- It requires overhead to support it.
If you have any comments or questions, feel free to start a conversation on the 3D Haven Discord server.
If you feel like you need non-square terrain support for your use case, please submit a Path Painter support ticket.