如何在Spritekit中测量sprite部分的体积或不透明像素数

// 获取sprite的纹理对象
let texture = sprite.texture!

// 创建像素缓冲区
let pixelBuffer = UnsafeMutablePointer<UInt8>.allocate(capacity: texture.size().width * texture.size().height * 4)

// 将sprite的纹理绘制到像素缓冲区中
let context = CGContext(data: pixelBuffer, width: Int(texture.size().width), height: Int(texture.size().height), bitsPerComponent: 8, bytesPerRow: Int(texture.size().width) * 4, space: CGColorSpaceCreateDeviceRGB(), bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue)
context?.translateBy(x: 0, y: texture.size().height)
context?.scaleBy(x: 1.0, y: -1.0)
context?.draw(texture.cgImage(), in: CGRect(x: 0, y: 0, width: texture.size().width, height: texture.size().height))

// 统计不透明像素的数量或计算体积
var opaquePixelCount = 0
for y in 0..<Int(texture.size().height) {
    for x in 0..<Int(texture.size().width) {
        let pixelData = pixelBuffer.advanced(by: (y * Int(texture.size().width) + x) * 4)
        let alpha = pixelData[3]
        if alpha > 0 {
            opaquePixelCount += 1
        }
    }
}

// 释放像素缓冲区的内存
pixelBuffer.deallocate()

// 输出结果
print("不透明像素数：\(opaquePixelCount)")