Bounce not working properly

NJL64

States.MOVE: if Input.is_action_just_released("move"): state = States.IDLE # change state elif Input.is_action_pressed("space_bar") and can_charge_player: state = States.CHARGE # change state elif collision: if collision.get_collider().name == "Bumper": velocity = velocity.bounce(collision.get_normal()) move_and_collide(velocity) print("Bumper") else: # run move code speed = speed_move # set speed to move speed velocity = direction_input * speed # move move_and_slide() # define movement and slide across walls anim_shell.play() # play animation

move_and_collide(velocity) strangely makes the player teleport a slight distance away. move_and_slide does nothing. I want the player to bounce away when colliding with "Bumper". Basically like pinball.

xyz

NJL64 move_and_collide() argument is supposed to be the motion vector, not velocity. Check the reference.

NJL64

xyz Sorry. I'm having a little struggle understanding. Are you saying I should put a different argument in "move_and_collide()" bracket instead of "velocity"?

My code is kinda built up from learning and trial and error, so I'm not necessarily very smart. What should I use instead do you think?

xyz

NJL64 https://docs.godotengine.org/en/4.5/classes/class_physicsbody2d.html#class-physicsbody2d-method-move-and-collide

NJL64

xyz I've been reading over this a lot of times, so I apologize if I'm still a little confused and overwhelmed by the information.

kuligs2

xyz whats the difference between vect2 and motion vector?

OP had this which velocity.bounce produce vect2

velocity = velocity.bounce(collision.get_normal())
move_and_collide(velocity)

xyz

NJL64 As an argument to 'move_and_collide()` you need to send the vector that represent body's relative motion on the current frame.

DaveTheCoder

See the second example here:
https://docs.godotengine.org/en/4.5/tutorials/physics/physics_introduction.html#move-and-collide

NJL64

Thank you both. I appreciate the additional guidance. It helps me to learn.

xyz

kuligs2 Vector2 is a type. "Motion vector" and "velocity vector" are two different physical quantities. Both are represented by the same vector2 type, but have different values and meanings. So asking what's the difference between vector2 and "motion vector" doesn't make much sense. There's no "difference" because "motion vector" IS vector2. The relevant question would be what's the difference between velocity and motion vector. And the answer is - motion vector is the amount of positional change caused by moving at some velocity for some amount of time. Strictly mathematically speaking: motion vector is an integral sum of the velocity vector over a time interval.

Fortunately, if the velocity is considered to be constant over the whole time interval, that scary looking integral reduces down to a simple multiplication:
delta_position = velocity * delta_time
delta_position is the motion vector.
And that's where the magical "multiplication by delta" mantra comes from 😉

DaveTheCoder

xyz Fortunately

It's not a matter of luck. The common way to compute the value of an integral of a variable expression is by a summation of small constant deltas. That's the purpose of the _physics_process callback.

xyz

DaveTheCoder Wow! Really?!

DaveTheCoder

xyz Really?!

No, I made that up.