Blender Python (bpy) code to iterate raycast until a predicate passes

rayCastConditional.py

import bpy
import bmesh
import mathutils
from math import radians, degrees
from mathutils.bvhtree import BVHTree

def rayCastConditional(ray, rayTarget, increment, predicate):
	"""Cast multiple rays until 'predicate' passes.
	ray: (p, direction)
	rayTarget: something with ray_cast() such as:
		mathutils.bvhtree.BVHTree
		bpy.types.Object
		bpy.types.Scene
	predicate: function(ray, ray_cast_hitTuple) that returns whether hit is satisfactory.
		N.b. different rayTarget types have different return tuples! Check the docs.
	returns: hit tuple from whichever rayTarget was provided.
	Example usage:
	rayCastConditional((Vector((0, 0, 2)), Vector((0, 0, -1))), bpy.context.scene, 0.01, lambda ray, hitTuple: ray[1].angle(hitTuple[2]) > radians(150))
	"""
	assert 2 == len(ray), "Non-2 len:%d of ray:%s" % (len(ray), ray)
	p, direction = ray
	p = p.copy() # since we are modifying and it might not be a copy already
	while True:
		hitTuple = rayTarget.ray_cast(p, direction)
		if hitTuple[1] is None:
			return hitTuple
		if predicate(ray, hitTuple):
			return hitTuple
		p += direction * increment