Navigation

Py2D navigation code is contained in the py2d.Navigation package. You can generate a NavMesh object from polygonal navigation data with holes using the function NavMesh.generate:

>>> mesh = NavMesh.generate(boundary, holes)

This will automatically calculate optimal paths between all polygons in the generated navigation mesh.

Pathfinding

With the navigation mesh generated, you can query the mesh for paths. Simply use the get_path method to find the optimal path from Vector v to Vector w:

>>> path = mesh.get_path(v,w) 

If a path between the two vectors can be solved by the mesh, get_path will return a NavPath object that contains the sequence of polygons to traverse. You can also call get_path with two polygons instead of vectors.

Path following

You can use the NavPath object to generate the actual vertices an agent will have to walk to in order to reach their target as they are needed. Simply call get_next_move_to everytime you arrive at a target vector and you will receive the next target.

A simple agent moving along a NavPath self.path from self.position to self.goal might have the following per-frame update code:

def update(self, time_elapsed):
	if not self.move_to and (self.position - self.goal).length_squared > 0.1:
		self.move_to = self.path.get_next_move_to(self.position, self.goal)

	if self.move_to: 
		direction = self.move_to - self.position
		self.position += direction.clamp() * (time_elapsed * self.speed)		
		if (self.position - self.move_to).length_squared < 0.0001: 
			self.move_to = None