如何在相机中绘制与iPhone中的Measure App尺寸相同的线节点?

问题描述

我尝试将AR应用程序作为iPhone中的Measure默认应用程序.(我基于github上的项目TBXark/Ruler)

I try make an AR app as a Measure default app in iPhone. ( I base on project TBXark/Ruler on github)

我绘制了startNode，endNode，圆柱线和SCNText.但是我无法管理尺寸的规模，它只能在近处读取，而在测量远平面时却很小.

I draw startNode, endNode, cylinder line, and SCNText. But I can't manage the scale of size, it only readable in near, and so small when measure far plane detect.

我有2个问题:

1. 在与Measure App接近或远近绘制时如何保持大小节点，圆柱体和文本相同

1. How to keep size node, cylinder and text same when draw near or far as Measure App

如何使用背景绘制scntext并对齐与Measure App相同的方向圆柱线.

How to draw scntext with background and align the same direction cylinder line as Measure App.

这是我的线节点类:

class LineNode: NSObject {

let startNode: SCNNode
let endNode: SCNNode
var lineNode: SCNNode?
let textNode: SCNNode
let sceneView: ARSCNView?

// init func
init(startPos: SCNVector3,
     sceneV: ARSCNView,
     color: (start: UIColor, end: UIColor) = (UIColor(hexCss: 0xF1B426), UIColor(hexCss: 0xD43278)),
     font: UIFont = UIFont.boldSystemFont(ofSize: 8) ) {
    sceneView = sceneV

    let scale = 1 / 400.0
    let scaleVector = SCNVector3(scale, scale, scale)

    func buildSCNSphere(color: UIColor) -> SCNSphere {
        let dot = SCNSphere(radius: 1)
        dot.firstMaterial?.diffuse.contents = color
        dot.firstMaterial?.lightingModel = .constant
        dot.firstMaterial?.isDoubleSided = true
        return dot
    }
    // startNode
    startNode = SCNNode(geometry: buildSCNSphere(color: color.start))
    startNode.scale = scaleVector
    startNode.position = startPos
    sceneView?.scene.rootNode.addChildNode(startNode)

    // endNode
    endNode = SCNNode(geometry: buildSCNSphere(color: color.end))
    endNode.scale = scaleVector
    // line with start to end
    lineNode = CylinderLine(parent: sceneView!.scene.rootNode,
                            v1: startNode.position,
                            v2: endNode.position,
                            radius: 0.001,
                            radSegmentCount: 16,
                            color: UIColor.white)

    sceneView?.scene.rootNode.addChildNode(lineNode!)
    // text show measure line length
    let text = SCNText (string: "--", extrusionDepth: 0.1)
    text.font = font
    text.firstMaterial?.diffuse.contents = UIColor(hexCss: 0xffa800)
    text.firstMaterial?.lightingModel = .constant
    text.alignmentMode = CATextLayerAlignmentMode.center.rawValue
    text.truncationMode = CATextLayerTruncationMode.middle.rawValue
    text.firstMaterial?.isDoubleSided = true
    textNode = SCNNode(geometry: text)

    textNode.scale = SCNVector3(1 / 500.0, 1 / 500.0, 1 / 500.0)

    super.init()
}

// update end node realtime
public func updatePosition(pos: SCNVector3, camera: ARCamera?, unit: MeasurementUnit.Unit = MeasurementUnit.Unit.centimeter) -> Float {
    // update endNode
    let posEnd = updateTransform(for: pos, camera: camera)
    if endNode.parent == nil {
        sceneView?.scene.rootNode.addChildNode(endNode)
    }
    endNode.position = posEnd
    // caculate new mid
    let posStart = startNode.position
    let middle = SCNVector3((posStart.x + posEnd.x) / 2.0, (posStart.y + posEnd.y) / 2.0 + 0.002, (posStart.z + posEnd.z) / 2.0)
    // update text measure
    let text = textNode.geometry as! SCNText
    let length = posEnd.distanceFromPos(pos: startNode.position)
    text.string = MeasurementUnit(meterUnitValue: length).roundUpstring(type: unit)
    text.materials.first?.diffuse.contents = UIColor.orange
    textNode.setPivot()
    textNode.position = middle
    if textNode.parent == nil {
        sceneView?.scene.rootNode.addChildNode(textNode)
    }

    lineNode?.removeFromParentNode()
    lineNode = lineBetweenNodeA(nodeA: startNode, nodeB: endNode)
    sceneView?.scene.rootNode.addChildNode(lineNode!)

    return length
    }
}

推荐答案

即使您离它仍然可读，我也用它来更新比例尺

I use this to update scale if even if you stay far away it still readable

func updateScaleFromCameraForNodes(_ nodes: [SCNNode], fromPointOfView pointOfView: SCNNode , useScaling: Bool){
        nodes.forEach { (node) in

            //1. Get The Current Position Of The Node
            let positionOfNode = SCNVector3ToGLKVector3(node.worldPosition)

            //2. Get The Current Position Of The Camera
            let positionOfCamera = SCNVector3ToGLKVector3(pointOfView.worldPosition)

            //3. Calculate The Distance From The Node To The Camera
            let distanceBetweenNodeAndCamera = GLKVector3Distance(positionOfNode, positionOfCamera)

            let a = distanceBetweenNodeAndCamera*1.75
            if(useScaling) {
                node.simdScale = simd_float3(a,a,a)

            }

        }
        SCNTransaction.flush()
    }

然后在渲染器updateAtTime中调用它

then called it in the renderer updateAtTime

self.updateScaleFromCameraForNodes(self.nodesAdded, fromPointOfView:
self.cameraNode, useScaling: true)

这篇关于如何在相机中绘制与iPhone中的Measure App尺寸相同的线节点?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！