Implementing UI Follow in Unity

In 3D games, there is a special kind of UI, that is, the UI that moves with the game object (such as name, health bar, etc.). This article mainly implements UI follow.

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Realize ideas

1. Convert the game object's world coordinates to screen coordinates.
2. Synchronizes following UI coordinates with game object screen coordinates (or a delta).
3. The UI that follows can be displayed or closed depending on whether the UI is on screen.
4. In actual projects, in addition to the position of the UI, it may also involve some custom synchronization operations such as zooming, whether to display (grass, etc.).

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Health bar follow effect:

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Code:

// 挂载在运动对象上
using UnityEngine;

[RequireComponent(typeof(Rigidbody))]
public class PlayerController : MonoBehaviour {
    public float speed = 10f;
    Rigidbody rb;

    void Start () {
        rb = GetComponent<Rigidbody>();
    }   

    void FixedUpdate() {
        float h = Input.GetAxisRaw("Horizontal") * speed * Time.deltaTime;
        float v = Input.GetAxisRaw("Vertical") * speed * Time.deltaTime;
        rb.MovePosition(transform.position + new Vector3(h, 0, v));
    }
}

// 挂载在运动对象上

using UnityEngine;

public class UIFollow : MonoBehaviour {
    public Vector2 offset;
    public RectTransform rectTransform; // 跟随UI

    void Update() {
        Vector2 screenPos = Camera.main.WorldToScreenPoint(transform.position);
        rectTransform.position = screenPos + new Vector2(offset.x, offset.y);

        if (screenPos.x > Screen.width || screenPos.x < 0 || screenPos.y > Screen.height || screenPos.y < 0) 
            rectTransform.gameObject.SetActive(false);
        else 
            rectTransform.gameObject.SetActive(true);
    }

}

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If there are any mistakes, please point them out.

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blog: http://blog.csdn.net/david_dai_1108