unity uGUIの重なりを判定

Question

unityのCanvas上にImageを2つ置き、それらが重なっているかを判定したいです。
現在、双方にCollider2Dをつけてみたのですが検出してくれません。
よろしくお願いします

Answer 1

サンプル書いてみたので参考にしてみてください。

ドラッグしたImageが重なった時だけカラーを赤にするサンプル

using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

public class DragImage : MonoBehaviour, IDragHandler
{
    [SerializeField] RectTransform TargetTransform;
    [SerializeField, Space(10)] Canvas Canvas;
    [SerializeField] Image Render;

    public bool IsOverlapImage{ get; private set; }

    Camera Camera;
    RectTransform Transform;

    void Awake()
    {
        Camera = Canvas.worldCamera;
        Transform = Render.GetComponent<RectTransform>();
    }

    void Start()
    {
        CheckOverlapAndChangeColor();
    }

    public void OnDrag(PointerEventData eventData)
    {
        Transform.position = GetPos(eventData.position);
        CheckOverlapAndChangeColor();
    }

    void CheckOverlapAndChangeColor()
    {
        IsOverlapImage = CheckOverlap(Transform, TargetTransform);
        Render.color = IsOverlapImage ? Color.red : Color.white;
    }

    bool CheckOverlap(RectTransform rectTrans1, RectTransform rectTrans2)
    {
        Rect rect1 = new Rect(rectTrans1.localPosition.x, rectTrans1.localPosition.y, rectTrans1.rect.width, rectTrans1.rect.height);
        Rect rect2 = new Rect(rectTrans2.localPosition.x, rectTrans2.localPosition.y, rectTrans2.rect.width, rectTrans2.rect.height);

        return rect1.Overlaps(rect2);
    }

    Vector3 GetPos(Vector3 screenPoint)
    {
        switch (Canvas.renderMode)
        {
            case RenderMode.ScreenSpaceOverlay:
                return screenPoint;
            case RenderMode.ScreenSpaceCamera:
                screenPoint.z = Canvas.planeDistance;
                return Camera.ScreenToWorldPoint(screenPoint);
            default :
                Debug.LogError("Canvasの設定をScreenSpaceOverlayまたはScreenSpaceCameraにしてください");
                return screenPoint;
        }
    }
}

参考にした記事

Check if UI elements/RectTransform are overlapping
https://stackoverflow.com/questions/42043017/check-if-ui-elements-recttransform-are-overlapping

Answer 2

普通にCollider2Dでできました