My player sprite get stuck to walls while moving along

Question

Hello,

My player sprite is moving along the wall (not even diagonal, just straight down) and get randomly blocked in the corner of some walls. By blocked, I mean that the Y movement is stopped. If I move him away from the wall, he might not be blocked again by the same wall and get blocked at some other walls, always at a corner.

The walls are all the same sprite and are of the same size.

I use 2D Box Colliders for the walls. The player sprite has a Box Collider 2D and a RigidBody 2D. I am not using any physics codes, I would just like to make it work with the built-in Unity physics.

I move the player by adjusting the velocity of the rigidbody according to Input:

RigidBody2D rb = GetComponent<Rigidbody2D>();
float horizontal = Input.GetAxisRaw ("Horizontal");
float vertical = Input.GetAxisRaw("Vertical");
Vector2 movement = new Vector2(horizontal, vertical).normalized *speed * Time.deltaTime;
this.rb.velocity = movement;

The player is set like this:

Do you have any idea why it behaves like this and how I could fix it?

Thanks for your help.

Answer 1

This is a common issue when dealing with tiled ground/walls/terrain and BoxCollider2D. Often player collider's corner get stuck with wall's corner even if everything is perfectly lined up. I may suppose that the reason of it - floating point precision problem.

To solve this, you can try a different ways:

• Change player's collider to EdgeCollider2D and tweak it to satisfy your needs.
• Change player's collider to circle/capsule. Sometimes it work fine for platformer-style games, but in top-down game like yours it will cause another problem like weird diagonaly moving around a corners.
• Apply PhysicsMaterial2D to walls or player and set it to zero Friction. It may help, if you are using built-in physics or gravity.
• Generate one big collider for connected walls at runtime. If there is no seams between colliders, player will not stuck.
• Detect collisions by yourself using Raycast.

Also you may read this two articles: this and this.