2D Top down physics with ground (slippery floor...)

Questions & Answers
1

Hello
I’m quite new to the Unity engine, and I’m currently working on a 2D top down game. I’m using Tilemaps to draw my levels, but I have a question. I’d like to create a slippery effect on some places of the map (like an ice floor). I’ve found a way, but I’m wondering if there are better solutions to achieve this goal.

I’m currently doing the following:

  • Created a new Tilemap on top of my default ground to draw my Ice patches on

  • Added a Tilemap Collider2D to that Tilemap and made it a trigger

  • When I enter the trigger, I update the movement of my player

  • I’ll add my code below

    using System.Collections;
    using System.Collections.Generic;
    using UnityEngine;

    public class MovementController : MonoBehaviour {

     [SerializeField]
 private float topSpeed = 2.0f;

 private bool facingRight = true;
 private bool facingDown = true;
 private bool onIce = false;

 private Rigidbody2D rbody;
 private Animator animator;

 void Start() {
     rbody = GetComponent<Rigidbody2D>();
     animator = GetComponent<Animator>();
     Physics2D.gravity = Vector2.zero;
     Debug.Log("Initialized Player");
 }

 void Update() {
     
 }

 void FixedUpdate() {
     updateMovement();
     updateAnimator();
     if (onIce && stoppedMoving()) {
         //print("Player stopped moving");
     }
 }

 void updateMovement() {

     //Get input
     float moveHorizontal = Input.GetAxis("horizontal");
     float moveVertical = Input.GetAxis("vertical");

     //Define wheter moving horizontal and/or vertical
     bool vertical = Mathf.Abs(Input.GetAxisRaw("vertical")) > 0.1f;
     bool horizontal = Mathf.Abs(Input.GetAxisRaw("horizontal")) > 0.1f;

     //Update movement
     if (horizontal && vertical)
         //rbody.velocity = new Vector2(moveHorizontal, moveVertical) * topSpeed * 3 / 4;
         rbody.AddForce(new Vector2(moveHorizontal * topSpeed, moveVertical * topSpeed) * 3 / 4);
     else
         rbody.AddForce(new Vector2(moveHorizontal * topSpeed, moveVertical * topSpeed));
     //rbody.velocity = new Vector2(moveHorizontal, moveVertical) * topSpeed;
     

     //Flip if needed
     if (moveHorizontal < 0 && facingRight)
         flipHorizontal();
     else if (moveHorizontal > 0 && !facingRight)
         flipHorizontal();

     //stop moving when needed too
     if (Mathf.Abs(Input.GetAxisRaw("horizontal")) < 0.1f && !onIce)
         rbody.velocity = new Vector2(0, rbody.velocity.y);
     if (Mathf.Abs(Input.GetAxisRaw("vertical")) < 0.1f && !onIce)
         rbody.velocity = new Vector2(rbody.velocity.x, 0);

 }

 void updateAnimator() {

     bool vertical = Mathf.Abs(Input.GetAxisRaw("vertical")) > 0.1f;
     bool horizontal = Mathf.Abs(Input.GetAxisRaw("horizontal")) > 0.1f;

     //Update animator
     //horizontal/vertical
     if (Mathf.Abs(Input.GetAxisRaw("vertical")) > 0.1f && Mathf.Abs(Input.GetAxisRaw("horizontal")) > 0.1f) {
         animator.SetBool("horizontal", true);
         animator.SetBool("vertical", false);
     }
     else {
         animator.SetBool("horizontal", horizontal);
         animator.SetBool("vertical", vertical);
     }
     //up/down
     if (facingDown && Input.GetAxisRaw("vertical") > 0.1f) {
         animator.SetBool("down", false);
         facingDown = false;
     }
     else if (facingDown && Input.GetAxisRaw("vertical") < -0.1f) {
         animator.SetBool("down", true);
         facingDown = true;
     }
     else if (!facingDown && Input.GetAxisRaw("vertical") < -0.1f) {
         animator.SetBool("down", true);
         facingDown = true;
     }
     else if (!facingDown && Input.GetAxisRaw("vertical") > 0.1f) {
         animator.SetBool("down", false);
         facingDown = false;
     }
 }

 void flipHorizontal() {

     facingRight = !facingRight;
     Vector3 localScale = transform.localScale;
     localScale.x *= -1;
     transform.localScale = localScale;
 }


 bool stoppedMoving() {
     return Mathf.Abs(rbody.velocity.x) < 0.05f && Mathf.Abs(rbody.velocity.y) < 0.05f;
 }

 void OnTriggerEnter2D(Collider2D other) {
     if (other.gameObject.tag == "Icy") {
         print("Entered ice collider");
         onIce = true;
     }
 }

 void OnTriggerExit2D(Collider2D other) {
     if (other.gameObject.tag == "Icy") {
         print("Exited ice collider");
         onIce = false;
     }
 }

    }

2

Rather than programming friction which is very tedious why not just use Unity - Manual: Physics Material 2D

Just create a sprite for normal ground and another for ice then place them together in a level. And set the friction on the ice physics material to something like 0.1 or lower to get a slippery effect