Errors in Yonaba's JPS

[horoman]

The function jump of Yonaba'y JPS contains some errors when allowDiagonal is false. It will then not jump at all.

[JakobTischler]

I noticed that as well, but I wouldn't really see this as a bug. JPS in general only works when diagonal jumps are allowed, so the "bug" for me is not that it's not working, but rather that there's no warning/error message or something like that.

[horoman]

You are right it works. But it works like AStar. There are no jumps. But there should be. I think I see at least three errors, whereof two are bugs in my eyes and one is just a "Unterlassung". Will write it into the lines (not right now but at least this week).

[horoman]

Made the comments into the initial commit.
But when I have now read your comment again, I am not sure anymore if I am right with my comments.

JPS in general only works when diagonal jumps are allowed

Have to think about that again.

[horoman]

JPS in general only works when diagonal jumps are allowed

This is a question of definition. In case of diagonal moves are forbidden, I have to perfom a search to the left and right in case of a vertical/horizontal move (with diagonal moves this is not necessary). Then it should work again.
We can just try it and see if it works.

[horoman]

Here the proof. Note that it really jumps at the start and the end.

[JakobTischler]

Yeah. Looking at the picture, I realise two things:

1. We definitely need allowDiagonal to be true. With a point distance of 5 metres, some tractors will have problems taking those 90° turns.
2. How come jumps weren't performed in the "middle parts"? The last section before the final jump could/should have been one single jump as well. I'm asking because I think we should aim for as few target points as possible, to get a smoother ride.

[horoman]

1. I agree
2. I will try to explain it in a few words. But maybe we can discuss that on Skype later this week. I agree on "the less points the better".

The algorithm does not know how the map looks like, it comes from the start and searches for a path. It also does not know where the area with wheat is narrow to pass it.
Therefore whenever it hits this area, this is a possible point to pass the area. Thought this is a jump point and added to the bin. If the path goes through such a point, then it shows up as a point in the path, means that it is not jumped over it.