将Sprite打入图集时会默认去掉边缘的alpha=0的部分
Unity的Image.IsRaycastLocationValid在判断alphaHitTestMinimumThreshold的时候会使用图集中的点判断alpha而不是原Sprite中的点
所以会导致无法正确获取到alpha,要修复这个BUG可以重写Image类
主要是添加了这段代码 其他都是原装的
//计算local在图集中的位置Rect spriteRect = overrideSprite.textureRect;local.x = local.x - overrideSprite.textureRectOffset.x + spriteRect.x;local.y = local.y - overrideSprite.textureRectOffset.y + spriteRect.y;//判断是否在当前图的范围内if (!overrideSprite.textureRect.Contains(local)){return false;}
其实只重写了IsRaycastLocationValid方法,但是要访问private方法 只能拷贝出来了
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;public class OverrideImage : Image
{private void _PreserveSpriteAspectRatio(ref Rect rect, Vector2 spriteSize){var spriteRatio = spriteSize.x / spriteSize.y;var rectRatio = rect.width / rect.height;if (spriteRatio > rectRatio){var oldHeight = rect.height;rect.height = rect.width * (1.0f / spriteRatio);rect.y += (oldHeight - rect.height) * rectTransform.pivot.y;}else{var oldWidth = rect.width;rect.width = rect.height * spriteRatio;rect.x += (oldWidth - rect.width) * rectTransform.pivot.x;}}private Vector4 _GetAdjustedBorders(Vector4 border, Rect adjustedRect){Rect originalRect = rectTransform.rect;for (int axis = 0; axis <= 1; axis++){float borderScaleRatio;// The adjusted rect (adjusted for pixel correctness)// may be slightly larger than the original rect.// Adjust the border to match the adjustedRect to avoid// small gaps between borders (case 833201).if (originalRect.size[axis] != 0){borderScaleRatio = adjustedRect.size[axis] / originalRect.size[axis];border[axis] *= borderScaleRatio;border[axis + 2] *= borderScaleRatio;}// If the rect is smaller than the combined borders, then there's not room for the borders at their normal size.// In order to avoid artefacts with overlapping borders, we scale the borders down to fit.float combinedBorders = border[axis] + border[axis + 2];if (adjustedRect.size[axis] < combinedBorders && combinedBorders != 0){borderScaleRatio = adjustedRect.size[axis] / combinedBorders;border[axis] *= borderScaleRatio;border[axis + 2] *= borderScaleRatio;}}return border;}private Vector2 _MapCoordinate(Vector2 local, Rect rect){Rect spriteRect = overrideSprite.rect;if (type == Type.Simple || type == Type.Filled)return new Vector2(spriteRect.position.x + local.x * spriteRect.width / rect.width, spriteRect.position.y + local.y * spriteRect.height / rect.height);Vector4 border = overrideSprite.border;Vector4 adjustedBorder = _GetAdjustedBorders(border / pixelsPerUnit, rect);for (int i = 0; i < 2; i++){if (local[i] <= adjustedBorder[i])continue;if (rect.size[i] - local[i] <= adjustedBorder[i + 2]){local[i] -= (rect.size[i] - spriteRect.size[i]);continue;}if (type == Type.Sliced){float lerp = Mathf.InverseLerp(adjustedBorder[i], rect.size[i] - adjustedBorder[i + 2], local[i]);local[i] = Mathf.Lerp(border[i], spriteRect.size[i] - border[i + 2], lerp);}else{local[i] -= adjustedBorder[i];local[i] = Mathf.Repeat(local[i], spriteRect.size[i] - border[i] - border[i + 2]);local[i] += border[i];}}return local + spriteRect.position;}public override bool IsRaycastLocationValid(Vector2 screenPoint, Camera eventCamera){if (alphaHitTestMinimumThreshold <= 0)return true;if (alphaHitTestMinimumThreshold > 1)return false;if (overrideSprite == null)return true;Vector2 local;if (!RectTransformUtility.ScreenPointToLocalPointInRectangle(rectTransform, screenPoint, eventCamera, out local))return false;Rect rect = GetPixelAdjustedRect();if (preserveAspect)_PreserveSpriteAspectRatio(ref rect, new Vector2(overrideSprite.texture.width, overrideSprite.texture.height));// Convert to have lower left corner as reference point.local.x += rectTransform.pivot.x * rect.width;local.y += rectTransform.pivot.y * rect.height;local = _MapCoordinate(local, rect);//计算local在图集中的位置Rect spriteRect = overrideSprite.textureRect;local.x = local.x - overrideSprite.textureRectOffset.x + spriteRect.x;local.y = local.y - overrideSprite.textureRectOffset.y + spriteRect.y;//判断是否在当前图的范围内if (!overrideSprite.textureRect.Contains(local)){return false;}// Convert local coordinates to texture space.float x = local.x / overrideSprite.texture.width;float y = local.y / overrideSprite.texture.height;try{return overrideSprite.texture.GetPixelBilinear(x, y).a >= alphaHitTestMinimumThreshold;}catch (UnityException e){Debug.LogError("Using alphaHitTestMinimumThreshold greater than 0 on Image whose sprite texture cannot be read. " + e.Message + " Also make sure to disable sprite packing for this sprite.", this);return true;}}
}