Fix path starting position while sneaking

[leijurv]

If you sneak off the edge of a block and start a path, the starting position will be not actually supported. If it was off the edge of a cliff, it's possible that the first movement will cause the player to just fall off.

Right now there is a heuristic, here:
https://github.com/cabaletta/baritone/blame/master/src/main/java/baritone/behavior/PathingBehavior.java#L259
ee8e44d

It's okay, but only if you're sneaking over a 1-high ledge.
It also requires this sketchy workaround:
https://github.com/cabaletta/baritone/blob/master/src/main/java/baritone/pathing/path/PathExecutor.java#L97

Which isn't great.

Instead we should figure out which block is actually supporting us. I don't really know how to do this.
First off, don't do any of this if the block below playerFeet is canWalkOn.
In the scenario where our current position isn't a valid place to start a path, we need to check the 8 adjacent blocks to see if they're supporting us.

[ZeroMemes]

Once the pathStart method is fixed, that workaround could be removed, correct?

[leijurv]

yes

[leijurv]

lol this is the same as #70

[leijurv]

I've come up with a "good enough" solution, in my opinion

• In the scenario where we are on the ground, yet the block directly below our feet isn't canWalkOn (i.e. we're sneaking off an edge), figure out the block we're sneaking off of, and start a path from there
• In the scenario where we are not on the ground, and the block directly below our feet isn't canWalkOn, but the block directly below that is canWalkOn, move our starting block down by one
• In all other scenarios, playerFeet is the path start

Here is a video demonstrating that algorithm in action, the block highlighted in white is where a path would start:
https://youtu.be/5jlVmMXFCxU