我有一个 SCNode,它是使用 SCNPlane 几何图形动态创建的,以使用 SceneKit 绘制平面。
如何确定该平面的法线向量?
这是一个展示我尝试过的东西的游乐场。我附上了绘制的结果场景的屏幕截图。我不认为有任何圆柱体代表在这个红色平面的法线向量处获得的向量。
//: Playground - noun: a place where people can play
import UIKit
import SceneKit
import PlaygroundSupport
// Set up the scene view
let frame = CGRect(
x: 0,
y: 0,
width: 500,
height: 300)
let sceneView = SCNView(frame: frame)
sceneView.showsStatistics = true
sceneView.autoenablesDefaultLighting = true
sceneView.allowsCameraControl = true
sceneView.scene = SCNScene()
// Setup our view into the scene
let cameraNode = SCNNode()
cameraNode.camera = SCNCamera()
cameraNode.position = SCNVector3(x: 0, y: 0, z: 3)
sceneView.scene!.rootNode.addChildNode(cameraNode)
// Add a plane to the scene
let plane = SCNNode(geometry: SCNPlane(width: 3,height: 3))
plane.geometry?.firstMaterial!.diffuse.contents = UIColor.red.withAlphaComponent(0.5)
plane.geometry?.firstMaterial?.isDoubleSided = true
sceneView.scene!.rootNode.addChildNode(plane)
/*
normalSource = [SCNGeometrySource geometrySourceWithData:data
semantic:SCNGeometrySourceSemanticNormal
vectorCount:VERTEX_COUNT
floatComponents:YES
componentsPerVector:3 // nx, ny, nz
bytesPerComponent:sizeof(float)
dataOffset:offsetof(MyVertex, nx)
dataStride:sizeof(MyVertex)];
*/
let dataBuffer = plane.geometry?.sources(for: SCNGeometrySource.Semantic.normal)[0].data
let colorArray = [UIColor.red, UIColor.orange, UIColor.yellow, UIColor.green, UIColor.blue, UIColor.systemIndigo, UIColor.purple, UIColor.brown, UIColor.black, UIColor.systemPink]
let sceneGeometrySource = dataBuffer!.withUnsafeBytes {
(vertexBuffer: UnsafePointer<SCNVector3>) -> SCNGeometrySource in
let sceneVectors = Array(UnsafeBufferPointer(start: vertexBuffer, count: dataBuffer!.count/MemoryLayout<SCNVector3>.stride))
var i=0
for vector in sceneVectors{
let cyl = SCNCylinder(radius: 0.05, height: 3)
cyl.firstMaterial!.diffuse.contents = colorArray[i].withAlphaComponent(0.8)
let lineNode = SCNNode(geometry: cyl)
lineNode.eulerAngles = vector
sceneView.scene!.rootNode.addChildNode(lineNode)
}
return SCNGeometrySource(vertices: sceneVectors)
}
PlaygroundSupport.PlaygroundPage.current.liveView = sceneView