Unity2DCheatsheet

A cheatsheet for Unity's 2D features. It's based on this cheat sheet but I've modified it for 2D.

Animation

Non-physics movement

Transform.position = Vector2.Lerp(...)
Transform.translate(X, Y, Z)

Physics

Rigidbodies

To make a GameObject under the control of the physics engine, add a Rigidbody2Dcomponent.

With Rigidbodies2D do not attempt to move them by Transform properties (rotation, scale, position). Instead apply forces.

rigidBody = GetComponent<RigidBody2D>();
rigidBody.AddForce(force...);

or

rigidBody = GetComponent<RigidBody2D>();
rigidBody.velocity = new Vector2( x , y );

or

rigidBody = GetComponent<RigidBody2D>();
rigidBody.MovePosition(toNewPosition);

Colliders

BoxCollider2D
CircleCollider2D
PolygonCollider2D

Floors, walls, and other motionless elements

Add a collider to an object, but don't add a Rigidbody component.

Collisions and Triggers

Normally colliders collide with other colliders, which means they apply force to each other.

Triggers do not apply forces. They are good to use when you want a character to move over an area (a "trigger") without boucing off of it or being blocked by it.

To make something a trigger in the Editor, check the "isTrigger" checkbox.

OnCollisionEnter2D
OnCollisionExit2D
OnCollisionStay2D

Triggers

OnTriggerEnter2D
OnTriggerExit2D
OnTriggerStay2D

Destroy

Removes a game object, component or asset

Destroy (myObject);

Spawn (instantiate)

Instantiate(gameObject, position, Quaternion.identity)A as GameObject;

GameObject Events

###Update() Called once per frame.

###FixedUpdate() Called multiple times per frame. Should be used when applying forces or other physics related functions.

LastUpdate()

Called once per frame after Update() has finished. Good for camera movement.

How to crash unity: Use a loop (for, while) inside of Update(), FixedUpdate(), or LastUpdate().

##Input

Conventional

Input.GetAxis("Horizontal")
Input.GetAxis("Vertical")

Mobile

Mobile uses an Input.Touch data structure.

Useful properties include position and deltaPosition (change in position since the last frame).

var particle : GameObject;
function Update () {
    for (var touch : Touch in Input.touches) {
        if (touch.phase == TouchPhase.Began) {
            // Construct a ray from the current touch coordinates
            var ray = Camera.main.ScreenPointToRay (touch.position);
            if (Physics.Raycast (ray)) {
                // Create a particle if hit
                Instantiate (particle, transform.position, transform.rotation);
            }
        }
    }
}

Useful Math Functions

Mathf.Max

Mathf.Min

###Mathf.Clamp Useful for forcing a player to say within a certain "bounds".

var pos = transform.position;
pos.x =  Mathf.Clamp(transform.position.x, -2.0f, 2.0f);

Mathf.PingPong

Rotation

Quarternion.identity

This is just another word for "no rotation".

Vector Variables

Vector2D.one
Vector2D.right
Vector2D.up
Vector2D.zero

Timing Variables

Time.deltaTime
Time.fixedTime
Time.time
Time.timeScale

---

Controlling the camera

For 2D, don’t mess with the Scene Gizmo. In Unity 5 the gizmo isn't even available when viewing in "2D" mode:

don't mess with this guy

If you mess with the Scene Gizmo and can't get back to your original camera position, close the Scene Tab and then reopen it.

Vertex snapping

When you are building tiles for your game, its easier if they just "snap" together.

However this feature is hard to find (there's no View > grid > snap to grid or anything Photoshop-like).

Snapping items together is called vertex snapping.

Hold down v + move the mouse

Holding down "v" while moving the mouse will make the pointer snap from "point" to "point". Once you have selected the point you want things to snap to, click and drag your object so it "snaps" beside the object you want to place it near.

Renaming a project

Quit Unity.

Rename the folder that contains the Unity project.

Restart Unity.

Click Open Other and choose the folder you just renamed.