# Rotating raycast2d accordingly to vector's reflection

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Hi,

I’ve got a player with raycast2d (laser2d) and where it’s ray collides with level walls I’m dynamically positioning another raycast2d (bounce_one), and want the new one to be casting as if it was a reflection of the first one from the wall (see image below). I can position it in the right place, I just can’t seem to get it to face where it should. I would greatly appreciate any advice.

Script sits on players node.

``````if laser2d.is_colliding():
var laser_coll_point = to_local(laser2d.get_collision_point())
var laser_coll_normal = to_local(laser2d.get_collision_normal())
bounce_one.position = laser_coll_point
var reflection = (laser_coll_point -
to_local(laser2d.position)).reflect(laser_coll_normal)
var angle = laser_coll_point.angle_to_point(reflection)
bounce_one.rotation = rotation + angle
``````

You can get a forward Vector2 for your original Raycast with Vector2(1 0).rotated(laser.rotation). Once you got that, you can bounce it with the normal v2.bounce(normal). Finally, you go back to a rotation with angle().

Hi @Lopy, thank you for the answer. I’ve tried your suggestion, but now the second raycast2d is pointing straight back at the first one.

``````	var laser_coll_point = to_local(laser2d.get_collision_point())
var laser_coll_normal = to_local(laser2d.get_collision_normal())
bounce_one.position = laser_coll_point
var forward = Vector2(1,0).rotated(laser2d.rotation)
var bounce = forward.bounce(laser_coll_normal)
bounce_one.rotation = bounce.angle()
``````

aya9 | 2020-12-28 11:09

The collision normal after function to_local() had to be normalized again (at least that is what debugger suggested), but still no joy. Screen

aya9 | 2020-12-28 13:02

The biggest problem seemed to be using local coordinates and not global ones. Also it’s either using bounce() or negating reflect(). Code that worked is attached below.

``````var laser_coll_point = laser2d.get_collision_point()
var laser_coll_normal = laser2d.get_collision_normal()
bounce_one.global_position = laser_coll_point
var forward = laser_coll_point - laser2d.global_position
var reflection = -forward.reflect(laser_coll_normal)
bounce_one.global_rotation = reflection.angle()
``````

Really, this has saved my day.

Many, many thanks!

zeitgeist | 2021-11-21 22:16

You’re very welcome. Nice to know my answer could actually be helpful to someone.

aya9 | 2021-11-22 10:24