ios - 在 SceneKit 节点周围添加边框

Question

我正在尝试使用点击手势突出显示 SceneKit 中的选定节点。不幸的是，我没能完成它。我能做的最好的事情就是在点击节点时更改 Material 。

let material = key.geometry!.firstMaterial!
material.emission.contents = UIColor.blackColor()

有人可以建议我可以只在对象周围添加边框或轮廓而不是更改整个节点的颜色吗？

Answer 1

基于@Karl Sigiscar 的回答和 SO 中的另一个回答，我想到了这个:

func createLineNode(fromPos origin: SCNVector3, toPos destination: SCNVector3, color: UIColor) -> SCNNode {
    let line = lineFrom(vector: origin, toVector: destination)
    let lineNode = SCNNode(geometry: line)
    let planeMaterial = SCNMaterial()
    planeMaterial.diffuse.contents = color
    line.materials = [planeMaterial]

    return lineNode
}

func lineFrom(vector vector1: SCNVector3, toVector vector2: SCNVector3) -> SCNGeometry {
    let indices: [Int32] = [0, 1]

    let source = SCNGeometrySource(vertices: [vector1, vector2])
    let element = SCNGeometryElement(indices: indices, primitiveType: .line)

    return SCNGeometry(sources: [source], elements: [element])
}


func highlightNode(_ node: SCNNode) {
    let (min, max) = node.boundingBox
    let zCoord = node.position.z
    let topLeft = SCNVector3Make(min.x, max.y, zCoord)
    let bottomLeft = SCNVector3Make(min.x, min.y, zCoord)
    let topRight = SCNVector3Make(max.x, max.y, zCoord)
    let bottomRight = SCNVector3Make(max.x, min.y, zCoord)


    let bottomSide = createLineNode(fromPos: bottomLeft, toPos: bottomRight, color: .yellow)
    let leftSide = createLineNode(fromPos: bottomLeft, toPos: topLeft, color: .yellow)
    let rightSide = createLineNode(fromPos: bottomRight, toPos: topRight, color: .yellow)
    let topSide = createLineNode(fromPos: topLeft, toPos: topRight, color: .yellow)

    [bottomSide, leftSide, rightSide, topSide].forEach {
        $0.name = kHighlightingNode // Whatever name you want so you can unhighlight later if needed
        node.addChildNode($0)
    }
}

func unhighlightNode(_ node: SCNNode) {
    let highlightningNodes = node.childNodes { (child, stop) -> Bool in
        child.name == kHighlightingNode
    }
    highlightningNodes.forEach {
        $0.removeFromParentNode()
    }
}