Buttons in Unity, without using UI?

Question

Is there a way in Unity to create a simple 2D button without using the UI layer. I have a game with a lot of buttons and I don't want to make the whole app in the UI. Some more controls are welcome too: switches, sliders etc.

PS. I saw NGUI and I don't like it so far. Anything else?

Answer 1

Is there a way in Unity to create a simple 2D button without using the UI layer

You can use Sprite/Sprite Render as a Button.First Create a GameObject and attach EventSystem and StandaloneInputModule to it. Attach Physics2DRaycaster to the Camera, implement IPointerClickHandler and override OnPointerClick function. Create a 2D Sprite by going to GameObject->2D Object->Sprite then attach your script to the Sprite. Here is a complete code to do that:

using UnityEngine;
using UnityEngine.EventSystems;
using System.Collections;

public class SPRITEBUTTON: MonoBehaviour, IPointerClickHandler,
                                  IPointerDownHandler, IPointerEnterHandler,
                                  IPointerUpHandler, IPointerExitHandler
{

    void Start()
    {
        //Attach Physics2DRaycaster to the Camera
        Camera.main.gameObject.AddComponent<Physics2DRaycaster>();

        addEventSystem();
    }

    public void OnPointerClick(PointerEventData eventData)
    {
        Debug.Log("Mouse Clicked!");
    }

    public void OnPointerDown(PointerEventData eventData)
    {
        Debug.Log("Mouse Down!");
    }

    public void OnPointerEnter(PointerEventData eventData)
    {
        Debug.Log("Mouse Enter!");
    }

    public void OnPointerUp(PointerEventData eventData)
    {
        Debug.Log("Mouse Up!");
    }
    public void OnPointerExit(PointerEventData eventData)
    {
        Debug.Log("Mouse Exit!");
    }

    //Add Event System to the Camera
    void addEventSystem()
    {
        GameObject eventSystem = null;
        GameObject tempObj = GameObject.Find("EventSystem");
        if (tempObj == null)
        {
            eventSystem = new GameObject("EventSystem");
            eventSystem.AddComponent<EventSystem>();
            eventSystem.AddComponent<StandaloneInputModule>();
        }
        else
        {
            if ((tempObj.GetComponent<EventSystem>()) == null)
            {
                tempObj.AddComponent<EventSystem>();
            }

            if ((tempObj.GetComponent<StandaloneInputModule>()) == null)
            {
                tempObj.AddComponent<StandaloneInputModule>();
            }
        }
    }

}

EDIT:

If this is a 3D GameObject/Mesh, then you need to add a simple collider to it. If it is just Sprite then you must add a 2D collider to the sprite.

Answer 2

Another approach that is even simpler, is to just add a BoxCollider2D component, then add the following methods to the a new componenent, say UIButton, where you will to perform the button actions :

1. void OnMouseOver()
2. void OnMouseDown()
3. void OnMouseUp()

This avoids the use of an EventSystem, StandaloneInputModule and Physics2DRaycaster.

Example :

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

public class UIButton : MonoBehaviour {

    public Sprite regular;
    public Sprite mouseOver;
    public Sprite mouseClicked;
    public TextMeshPro buttonText;

    // Use this for initialization
    void Start () {

    }

    // Update is called once per frame
    void Update () {

    }

    private void OnMouseDown()
    {

    }

    private void OnMouseEnter()
    {

    }

    private void OnMouseExit()
    {

    }

    private void OnMouseUpAsButton()
    {

    }
}

Tested in unity 2018.1. One difference I initially noticed to this and the above approach is that the right mouse button click is not detected in this model, but is detected in the EventSystemModel.