How can I remove object by raycast?

Question

I want to remove obstacle between points A and B.

I tried to use bhvtree but I have an error

import bpy
from mathutils.bvhtree import BVHTree

a = bpy.data.objects['a']
b = bpy.data.objects['b']
bvhtree = BVHTree.FromObject(a, b)

Traceback (most recent call last):
  File "<blender_console>", line 1, in <module>
  File "Text", line 6, in <module>
TypeError: expected 'Depsgraph' type found 'Object' instead

I don't know what is the Depsgraph type!

Answer 1

Scene raycast

Having recently answered https://blender.stackexchange.com/a/192827/15543 it appears this is another good contender for scene raycast.

Given two global points in the scene raycast from one in direction of other as far as the distance between them Repeat until there are no more obstacles to hit.

import bpy
from bpy import context

from mathutils import Vector

a = Vector((-5, 0, 0))
b = Vector((5, 0, 0))

scene = context.scene

while True:
    hit, loc, norm, idx, ob, M = scene.ray_cast(
            context.evaluated_depsgraph_get(),
            a,
            (b - a),
            distance=(b - a).length,
            )
    if hit:
        print(f"Hit, removing {ob.name}")
        bpy.data.objects.remove(ob)
        continue
    break

Answer 2

"Depsgraph" stands for "dependency graph", meaning what the objects are depending on (such as modifiers, for instance) and can influence their current state or geometry.

You can obtain it by

bpy.context.evaluated_depsgraph_get()

You can have a look to the documentation here.

A way to do it is to make the obstacle the BVH object and raycast from 'a' origin in the direction of 'b'.

import bpy
from mathutils.bvhtree import BVHTree

a = bpy.data.objects['a']
b = bpy.data.objects['b']
obstacle = bpy.data.objects['Cube']

# Get the dependency graph
depsgraph = bpy.context.evaluated_depsgraph_get()

# Make a BVH tree from the obstacle
bvhtree = BVHTree.FromObject(obstacle, depsgraph)

# Inverted world matrix: to have objects coordinates in obstacle world
obs_world_inv = obstacle.matrix_world.inverted()

# Origin of the raycast
origin = obs_world_inv @ a.location
# Direction of the raycast
direction = obs_world_inv @ (b.location - a.location)

# Raycast result is a tuple of:
# - location of the hit
# - its normal
# - its face index 
# - the distance from the origin
result = bvhtree.ray_cast(origin, direction)

if result[0]:
    obstacle.hide_render = True    
    obstacle.hide_viewport = True    
    print( "Hidden" )
else:
    print( "Not found" )