Unity3D C# Inheritance Issue

Question

I have two c# scripts.
One for the cannon:

using UnityEngine;
using System.Collections;

public class CannonScript : MonoBehaviour {

    public GameObject bullet; //bullet object
    public Transform spawnpoint; //spawn point
    float bulletspeed=-3000f; //bullet speed
    public int bullets=10; //number of bullets

    void Update () {
        if ((Input.GetKeyDown ("space") || Input.GetMouseButtonDown(0)) && bullets > 0) {
            GameObject newbullet; //make a new bullet
            newbullet=Instantiate(bullet,spawnpoint.position, spawnpoint.rotation)as GameObject; //instantiate the new bullet
            newbullet.rigidbody.AddForce(spawnpoint.forward * bulletspeed); //add force to the new bullet
            bullets--; //decrease the number of bullets left
        }
    }
}

Another for the UI text on the screen:

using UnityEngine;
using UnityEngine.UI;
using System.Collections;

public class BulletCountScript : CannonScript { //inherit from the CannonScript

    Text text;

    void Start () {
        text = GetComponent<Text> ();
    }

    void Update () {
        text.text = bullets.ToString(); //display the number of bullets
    }
}

When I run it, the UI text on the screen never changes.
I know the CannonScript is working properly, because I can only shoot 10 bullets.
How can I make my UI text display the amount of bullets left?
Am I doing something wrong with inheritance?

ʇolɐǝz ǝɥʇ qoq · Accepted Answer · 2015-03-07 22:44:24Z

3

I think you are missunderstanding the inheritance concept. The problem I see is both classes are different instances, so that is the reason because the text is always the same.

To achieve what you want, just do something like this:

using UnityEngine;
using UnityEngine.UI;
using System.Collections;

public class BulletCountScript : MonoBehaviour { 

    public CannonScript cannon;
    Text text;

    void Start () {
        text = GetComponent<Text> ();
    }

    void Update () {
        text.text = cannon.bullets.ToString(); //display the number of bullets
    }
}

Just drag the object who owns the CannonScript to the game object attribute at the BulletCountScript, now, both of them are referencing the same instance.

I hope this helps! Good luck!

edited Mar 7, 2015 at 22:44

ʇolɐǝz ǝɥʇ qoq

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answered Mar 7, 2015 at 21:55

Drewen

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1 Comment

Mike B Over a year ago

Inheritance can be a double edged sword and often using composition like this is a better and more flexible solution

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