CSHARP

Unity 2d

/*
**Beware; fliping a character using the sprite renderer won't flip important components like colliders attached to it
**To Correctly flip a character, Flip the character by changing the y rotation or by changing the scale of the x axis to -1 or 1
*/

///Fliping a character in Unity 2D
	//Declare variables
	bool _facingRight

	void Update()
	{
		if (Input.GetAxisRaw("Horizontal") > 0  &&  !_facingRight)
        {
            Flip();
        }
        
        //
   		else if (_moveHorizontal < 0 && _facingRight )
        {
            //calls the flip method
            Flip();
        }
 	}   
  
	//Flip Method 
    void Flip()
    {

        //flips the character along the x axis using the sprite renderer correspondingly
        gameObject.GetComponent<SpriteRenderer>().flipX = !gameObject.GetComponent<SpriteRenderer>().flipX;
        
        //Sets the facingright bool to the opposite of what its currently at to prevent repeated flipping
        _facingRight = !_facingRight;
        
        //Flips the character by Rotating the character 180 degrees along the y axis
        //gameObject.GetComponent<Rigidbody2D>().transform.Rotate(0, 180, 0);
        
        //Flips the character by the changing the scale of the x axis to 1 or minus 1
        //gameObject.GetComponent<Rigidbody2D>().transform.localScale = new Vector3(transform.localScale.x*-1, transform.localScale.y, transform.localScale.z);
        
        
    }

unity 2d

/* How to scale any asset to your screen size:
Set up:
- Click on your asset or sprite in the project folder and change the
	'Pixels per Unit' from the default 100, to the resolution of the sprite.
    (e.g. 64, 128, 256, etc.) Then click 'Apply' at the bottom right.
- Attach the first script to the main camera (or an object that doesn't 
	effect the world).
- Attach the second script to the asset/sprite you want to scale.
*/

// First script
using UnityEngine;
public class ScreenSize : MonoBehaviour
{
    public static float GetScreenToWorldHeight
    {
        get
        {
            Vector2 topRightCorner = new Vector2(1, 1);
            Vector2 edgeVector = Camera.main.ViewportToWorldPoint(topRightCorner);
            var height = edgeVector.y * 2;
            return height;
        }
    }
    public static float GetScreenToWorldWidth
    {
        get
        {
            Vector2 topRightCorner = new Vector2(1, 1);
            Vector2 edgeVector = Camera.main.ViewportToWorldPoint(topRightCorner);
            var width = edgeVector.x * 2;
            return width;
        }
    }
}

// Second script
using UnityEngine;
public class Scaler : MonoBehaviour
{
	void Start()
	{
    	float width = ScreenSize.GetScreenToWorldWidth;
    	transform.localScale = Vector3.one * width;
	}
}

//=============================================================================
// Edit: After messing around with this a bit, this is a way to automatically
//		 fit a sprite to the monitors X and Y screen dimensions.

// Second script (NEW)
using UnityEngine;
public class Scaler : MonoBehaviour
{
	void Start()
	{
    	// Declare width and height values
    	float width = ScreenSize.GetScreenToWorldWidth;
    	float height = ScreenSize.GetScreenToWorldHeight;
        
        // Check if the window is landscape
        if (width > height)
        {
            transform.localScale = Vector3.one * height;
        }

		// Check if the window is portrait
        if (height > width)
        {
            transform.localScale = Vector3.one * width;
        }
        
        // Check if the length of the window edges are equal
        if (width == height)
        {
            transform.localScale = Vector3.one * ((width + height) / 2);
        }
	}
}

// Sorry for the long answer ;)

Unity 2d

void FixedUpdate()
{
    //Use Velocity
	if (Input.GetKey(KeyCode.D))
        {
        	//add velocity to rigidbody 3 units along x axis and 0 units along y axis
            //Velocity is not affected by Gravity
            //Velocity i constant in every frame I.e Force=3
            //Velocity starts from the initial value stated which in this case is 3
            //rigidbody2d.velocity = new vector2(x,y);
            //x is sideways and y is upwards
            
            rb2d.velocity = new Vector2(3,0);
            
            
           //To gradually increase Velocity in each frame see the line of code below
           
           rb2d.velocity += new Vector2(3,0);
        }
        
	//OR Use Force
	if (Input.GetKey(KeyCode.D))
        {
        	//Gradually adds Force/velocity to rigidbody 4 units to the right along x axis
            //Force is affected by gravity and Drag
            //Force starts from 0 and increases gradually by 4 units per frame
            rb2d.AddForce (Vector2.right * 4);
        }
}