Unity 2D – Laser Defender (2)

Continued

Movement & Time

Create a new script for player, and open it (Also create a new folder for it). The next step is to make my ship move. In visual studio which open script for me, add code as below:

player.cs:

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

public class Player : MonoBehaviour
{
    // Start is called before the first frame update
    void Start()
    {

    }

    // Update is called once per frame
    void Update()
    {
        Move();
    }

    private void Move()
    {
        var deltaX = Input.GetAxis("Horizontal"); // Edit -> Project Setting -> Input Manager
        var newXPos = transform.position.x + deltaX;
        transform.position = new Vector2(newXPos, transform.position.y); // Change the position
    }

}

Time.deltaTime

Now our player’s ship could move along the x-coordinate. But it moves a little bit fast. To modify this, we should use Time.deltaTime which make games frame-rate independent, it means no matter your machine runs fast or slow you will get same experience.

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

public class Player : MonoBehaviour
{

    [SerializeField] float moveSpeed = 10f; // speed up otherwise too slow
    // Start is called before the first frame update
    void Start()
    {

    }

    // Update is called once per frame
    void Update()
    {
        Move();
    }

    private void Move()
    {
        var deltaX = Input.GetAxis("Horizontal") * Time.deltaTime * moveSpeed; // Edit -> Project Setting -> Input Manager
        //Debug.Log(deltaX);
        var newXPos = transform.position.x + deltaX;
        transform.position = new Vector2(newXPos, transform.position.y); // Change the position
    }

}

And then add more codes for moving along the y coordinate.

ViewPortToWorldPoint()

Def: converts the position of something as it relates to the camera view, into a world space value. This API we can use for constraining the range of our space ship moving, so we won’t lose our ship sprite in the game:

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

public class Player : MonoBehaviour
{

    [SerializeField] float moveSpeed = 10f;

    float xMin;
    float xMax;
    float yMin;
    float yMax;

    // Start is called before the first frame update
    void Start()
    {
        SetUpMoveBoundaries();
    }

    private void SetUpMoveBoundaries()
    {
        //throw new NotImplementedException();
        Camera gameCamera = Camera.main;
        xMin = gameCamera.ViewportToWorldPoint(new Vector3(0, 0, 0)).x;
        xMax = gameCamera.ViewportToWorldPoint(new Vector3(1, 0, 0)).x;
        yMin = gameCamera.ViewportToWorldPoint(new Vector3(0, 0, 0)).y;
        yMax = gameCamera.ViewportToWorldPoint(new Vector3(0, 1, 0)).y;
    }

    // Update is called once per frame
    void Update()
    {
        Move();
    }

    private void Move()
    {
        var deltaX = Input.GetAxis("Horizontal") * Time.deltaTime * moveSpeed; // Edit -> Project Setting -> Input Manager
        var deltaY = Input.GetAxis("Vertical") * Time.deltaTime * moveSpeed;

        var newXPos = Mathf.Clamp(transform.position.x + deltaX, xMin, xMax);
        var newYPos = Mathf.Clamp(transform.position.y + deltaY, yMin, yMax);

        transform.position = new Vector2(newXPos, newYPos); // Change the position
    }

}

Of course we can add a padding value into the file.