[1.12.2] Checking if Path exists

[Tschipp]

I'm writing some entity AI, which searches for blocks in a certain range and moves to them if it finds them.

It works good, but the problem that I'm facing now is that the entity also moves to the block, even if it's in a position that it can never reach (completely encased behind walls).

 

To try exclude these positions from valid ones, I added a check that calls

entity.getNavigator().getPathToPos(pos)

and checks if the path is null (because I thought it would be null if there was no available path).

Sadly, that doesn't work. The entity now just walks against the wall and stays there until I remove it.

 

Is there a way of checking if valid path to a position can be made before walking to it?

 

[V0idWa1k3r]

Look at PathNavigateGround#isDirectPathBetweenPoints, I think that one is a direct check of whether the entity can actually navigate to the point.

That said if you keep giving the entity an invalid path every time it asks for one then it will keep getting stuck. You need to check whtether the block is reachable before accepting it as a valid pathing target.

[Tschipp]

  On 11/18/2018 at 10:40 AM, V0idWa1k3r said:

Look at PathNavigateGround#isDirectPathBetweenPoints, I think that one is a direct check of whether the entity can actually navigate to the point.

That said if you keep giving the entity an invalid path every time it asks for one then it will keep getting stuck. You need to check whtether the block is reachable before accepting it as a valid pathing target.

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isDirectPathBetweenPoints is protected, but I'll try reflecting it and see if it doesn't impact performance too much.

My plan is of course to only make the entity walk to the position, if it is actually reachable.

[Tschipp]

Not sure... it always seems to return false for some reason, even if a path is available:

boolean result = (boolean) isDirectPathBetweenPoints.invoke(nav, new Vec3d(start.getX(), start.getY(), start.getZ()), new Vec3d(end.getX(), end.getY(), end.getZ()), (int)entity.width, (int)entity.height, (int)entity.width);

 

[Cadiboo]

You might want to use a method handle to reduce the overhead of reflection. Example

[Tschipp]

  On 11/18/2018 at 1:16 PM, Cadiboo said:

You might want to use a method handle to reduce the overhead of reflection. Example

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Good idea, but the way I have it right now it still always returns false. I'm suspecting it has something to do with the sizeX, sizeY and sizeZ parameters. What exactly to they do, and what should their values be in my example?

[Cadiboo]

I’m pretty sure that casting your entity size (float) to an int won’t be helping whatever your problem is. I’m not sure what they do, but you could look in the method at what happens to them. 

[Tschipp]

I'm not sure what's wrong. I give the method the same parameters as vanilla does when moving entities, the entity height and width...

 

The method always returns false at one of the isSafeToStandAt in isDirectPathBetweenPoints. I should probably also mention that the position where the entity should walk is a block of water, that might be why it's failing.

 

Is there any other way than isDirectPathBetweenPoints?

Edited November 19, 2018 by Tschipp