此 Alpha 阈值指定要将事件视为图像“碰撞”时像素必须具有的最小 Alpha 值。
小于阈值的 Alpha 值将导致射线投射事件通过图像。值 1 会导致只有完全不透明的像素在图像上注册射线投射事件。只使用从图像 Sprite 检索的 Alpha 值进行测试,图像 Graphic.color 的 Alpha 值将被忽略。
alphaHitTestMinimumThreshold 默认为 0;图像矩形内的所有射线投射事件均视为碰撞。为了使大于 0 的值能起作用,图像使用的 Sprite 必须具有可读像素。这可以通过在 Sprite 的高级纹理导入设置中启用 Read/Write enabled 并为 Sprite 禁用镶嵌来实现。
using UnityEngine; using System.Collections; using UnityEngine.UI; // Required when Using UI elements.
public class ExampleClass : MonoBehaviour { public Image theButton;
// Use this for initialization void Start() { theButton.alphaHitTestMinimumThreshold = 0.5f; } }
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