【问题标题】：How to add Shadow on surface plane?如何在表面平面上添加阴影？
【发布时间】：2019-04-20 11:53:59
【问题描述】：

我有一个问题，在ARView中显示物体上的阴影但没有显示在表面上，我附上了尝试代码？它正在工作在对象上显示阴影但不显示在表面上。 Show Image

代码：

var light2 = SCNLight()
var lightNodeb2 = SCNNode()
light2.castsShadow = true
light2.automaticallyAdjustsShadowProjection = true
light2.maximumShadowDistance = 40.0
light2.orthographicScale = 1
light2.type = .directional
light2.shadowMapSize = CGSize(width: 2048, height: 2048)
light2.shadowMode = .forward
light2.shadowSampleCount = 128
light2.shadowRadius = 3
light2.shadowBias  = 32
light2.zNear=1;
light2.zFar=1000;
lightNodeb2.light = light2
lightNodeb2.position = SCNVector3(x: -1, y: 10, z: 1)
lightNodeb2.rotation = SCNVector4Make(2, 0, 0, -Float.pi / 3) 
self.sceneView.scene.rootNode.addChildNode(lightNodeb2)

【问题讨论】：

标签： ios swift scenekit augmented-reality arkit

【解决方案1】：

我在这里看到 2 个可能的问题：

您的灯设置正常。我认为第一个问题如下：您在场景图中将程序化灯光与“非程序化”3D 对象一起使用。

检查一下。在这段代码中，所有对象都是程序化的：

let sphereNode1 = SCNNode(geometry: SCNSphere(radius: 1))
sphereNode1.position = SCNVector3(x: 0, y: 5, z: 3)
scene.rootNode.addChildNode(sphereNode1)

let sphereNode2 = SCNNode(geometry: SCNSphere(radius: 3))
sphereNode2.position = SCNVector3(x: 0, y: 1, z: 0)
scene.rootNode.addChildNode(sphereNode2)

let boxNode = SCNNode(geometry: SCNBox(width: 20, height: 0.1, length: 20, chamferRadius: 0))
boxNode.position = SCNVector3(x: 0, y: -3, z: 0)
scene.rootNode.addChildNode(boxNode)

let light2 = SCNLight()
let lightNodeb2 = SCNNode()
light2.castsShadow = true
light2.automaticallyAdjustsShadowProjection = true
light2.maximumShadowDistance = 40.0
light2.orthographicScale = 1
light2.type = .directional
light2.shadowMapSize = CGSize(width: 2048, height: 2048)

light2.shadowMode = .deferred    // Renders shadows in a postprocessing pass

light2.shadowSampleCount = 128
light2.shadowRadius = 3
light2.shadowBias = 32
light2.zNear = 1
light2.zFar = 1000
lightNodeb2.light = light2

// DIRECTIONAL LIGHT POSITION doesn't matter. Matters only its direction.
// lightNodeb2.position = SCNVector3(x: -1, y: 10, z: 1)

lightNodeb2.rotation = SCNVector4(2, 0, 0, -Float.pi/3)
scene.rootNode.addChildNode(lightNodeb2)

所有对象Shadow castings默认为On。

第一个问题的解决方案：

要使您的 3D 模型可供虚拟编程灯访问，请使用以下方法：

func childNode(withName name: String, recursively: Bool) -> SCNNode? {
    return SCNNode()
}  

let geometryNode = childNode(withName: "art.scnassets/your3Dmodel", 
                             recursively: true)!

scene.rootNode.addChildNode(geometryNode)

第二个问题的解决方案：

如果你想要一个带有阴影的隐藏平面，请使用以下代码：

hiddenPlaneNode.castsShadow = false
hiddenPlaneNode.geometry?.firstMaterial?.lightingModel = .constant
hiddenPlaneNode.geometry?.firstMaterial?.isDoubleSided = true
hiddenPlaneNode.geometry?.firstMaterial?.readsFromDepthBuffer = true
hiddenPlaneNode.geometry?.firstMaterial?.writesToDepthBuffer = true
hiddenPlaneNode.geometry?.firstMaterial?.colorBufferWriteMask = []

light2.shadowMode = .deferred

【讨论】：