有什么方法可以反转/翻转结果图吗？

Question

使用 iOS - Swift Xcode 14 我使用一些点绘制了图像......并且我得到了图像作为输出。但该图像是倒置或翻转的图像。 我使用了几个代码来翻转/反转图像，但没有一个代码起作用。 通过使用一些代码，结果图像会超出屏幕。 这里提供的代码是 90% 正确的代码，但图像被翻转/反转。

import SceneKit

class StairTwoDSceneViewController: UIViewController {

    var plotPointsArray: [[Double]] = [[0.0,0.0,0.0], [0.229,0.0,0.005], [0.229,-0.0249,0.1926], [0.4566,-0.0249,0.2073], [0.4341,-0.0315,0.3989],[0.6754,-0.0315,0.4039],[0.6513,-0.0315,0.5892], [0.8782,-0.0315,0.5971], [0.8541,-0.0315,0.7834],[1.0765,-0.0315,0.78781]]
    let lineWidth: CGFloat = 0.1 // Adjust this value to increase or decrease line thickness
    let cornerRadius: CGFloat = 0.02 // Adjust this value to control the size of the corner circles

    override func viewDidLoad() {
        super.viewDidLoad()
        let sceneView = SCNView(frame: view.bounds)
        sceneView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        view.addSubview(sceneView)

        let scene = SCNScene()

        if plotPointsArray.count > 0 {
            let pointsNode = SCNNode()

            for (index, point) in plotPointsArray.enumerated() {
                guard point.count == 2 || point.count == 3 else {
                    continue // Skip invalid points
                }

                // Adjust the y-coordinate to place the green sphere at the left bottom
                let spherePosition = SCNVector3(
                    x: Float(point[0]),
                    y: Float(point.count == 2 ? -0.0315 : -point[1]), // Flip and adjust y-coordinate
                    z: Float(point[point.count - 1])
                )
                let sphereNode = drawSphere(at: spherePosition, radius: cornerRadius, color: index == 0 ? UIColor.green : UIColor.red)
                pointsNode.addChildNode(sphereNode)
            }

            scene.rootNode.addChildNode(pointsNode)

            for i in 0..<plotPointsArray.count - 1 {
                let currentPoint = plotPointsArray[i]
                let nextPoint = plotPointsArray[i + 1]

                guard currentPoint.count == nextPoint.count else {
                    continue // Skip invalid points
                }

                let start = SCNVector3(currentPoint[0], currentPoint.count == 2 ? -0.0315 : -currentPoint[1], currentPoint[currentPoint.count - 1])
                let end = SCNVector3(nextPoint[0], nextPoint.count == 2 ? -0.0315 : -nextPoint[1], nextPoint[nextPoint.count - 1])

                let lineGeometry = SCNGeometry.lineGeometry(from: start, to: end)
                let lineNode = SCNNode(geometry: lineGeometry)
                scene.rootNode.addChildNode(lineNode)
            }
        }

        let cameraNode = SCNNode()
        cameraNode.camera = SCNCamera()
        cameraNode.eulerAngles.x = -Float.pi / 2
        cameraNode.eulerAngles.y = 0
        cameraNode.position = SCNVector3(0.5, 2.5, 0.5)
        scene.rootNode.addChildNode(cameraNode)

        sceneView.scene = scene
        sceneView.backgroundColor = UIColor.black
        sceneView.allowsCameraControl = true
    }



    func drawLine(from start: SCNVector3, to end: SCNVector3, thickness: CGFloat, color: UIColor) -> SCNNode {
        let lineGeometry = SCNGeometry.lineGeometry(from: start, to: end)
        lineGeometry.firstMaterial?.diffuse.contents = color

        let lineNode = SCNNode(geometry: lineGeometry)
        lineNode.position = SCNVector3((start.x + end.x) / 2, (start.y + end.y) / 2, (start.z + end.z) / 2)
        lineNode.eulerAngles.z = -atan2(end.x - start.x, end.y - start.y)

        return lineNode
    }

    func drawSphere(at position: SCNVector3, radius: CGFloat, color: UIColor) -> SCNNode {
        let sphereGeometry = SCNSphere(radius: radius)
        let sphereNode = SCNNode(geometry: sphereGeometry)
        sphereNode.position = position
        sphereNode.geometry?.firstMaterial?.diffuse.contents = color
        return sphereNode
    }
}

extension SCNGeometry {
    static func lineGeometry(from start: SCNVector3, to end: SCNVector3) -> SCNGeometry {
        let indices: [Int32] = [0, 1]

        let source = SCNGeometrySource(vertices: [start, end])
        let element = SCNGeometryElement(indices: indices, primitiveType: .line)

        return SCNGeometry(sources: [source], elements: [element])
    }
}
extension UIImage {
    func rotate(degrees: CGFloat) -> UIImage? {
        UIGraphicsBeginImageContextWithOptions(self.size, false, self.scale)
        guard let context = UIGraphicsGetCurrentContext() else {
            return nil
        }
        context.rotate(by: degrees * CGFloat.pi / 180)
        self.draw(in: CGRect(origin: .zero, size: self.size))
        let rotatedImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return rotatedImage
    }
}

其实我想要像下面这样的倒立图像

注意：不要更改积分，积分是从后端获取的。我在这里使用了样本点

我需要翻转/反转图像。

Answer 1

使用您生成的“楼梯台阶”，相机从 Y 角度 观察 ...“楼梯”在 Z 角度下降。

根据您想要做什么，您可以翻转相机：

    cameraNode.eulerAngles.x = -Float.pi / 2
    //cameraNode.eulerAngles.y = 0
    cameraNode.eulerAngles.y = -Float.pi / 2

或者，平移 Z 坐标以反转楼梯：

    if plotPointsArray.count > 0 {
        let pointsNode = SCNNode()

        // only use elements that have x,y,z values
        plotPointsArray.removeAll(where: {$0.count != 3})

        // will never fail (because we're only here if .count > 0)
        //  but safely unwrap anyway
        guard let lastPoint = plotPointsArray.last
        else { return }
        
        // assuming for now the z-values are from 0.0 to a positive value
        let maxZ = lastPoint[2]
        
        for (index, point) in plotPointsArray.enumerated() {
            
            // Adjust the Z-coordinate to place the green sphere at the left bottom
            let spherePosition = SCNVector3(
                x: Float(point[0]),
                y: Float(point[1]),
                z: Float(point[2] - maxZ)
            )

            let sphereNode = drawSphere(at: spherePosition, radius: cornerRadius, color: index == 0 ? UIColor.green : UIColor.red)
            pointsNode.addChildNode(sphereNode)
        }
        
        scene.rootNode.addChildNode(pointsNode)
        
        // let's use those sphere nodes to generate the
        //  "connecting lines" instead of re-converting the plotPointsArray
        var startVect: SCNVector3 = pointsNode.childNodes[0].position
        
        for (i, n) in pointsNode.childNodes.enumerated() {
            
            // skip the first time through
            //  since we have only the starting point
            guard i != 0 else {
                continue
            }
            
            let nextVect = n.position
            
            let lineGeometry = SCNGeometry.lineGeometry(from: startVect, to: nextVect)
            let lineNode = SCNNode(geometry: lineGeometry)
            
            scene.rootNode.addChildNode(lineNode)
            
            startVect = nextVect
        }

    }