从起始值到终止值绘制直线ARKit [英] Draw straight line from start value to end value ARKit

问题描述

一如既往，我需要您的帮助.我需要从一个起始值(声明为 SCNVector3 )绘制一条直线，并将其连接到现实世界中直到终点的位置.

As always I need your help. I need to draw a straight line from a start value (declared as SCNVector3) and connected to the position in the real world till the end point.

有人可以用几行代码向我解释我该怎么做?谢谢！

Can someone explain to me with some lines of code how can I do it? Thank you!

推荐答案

您需要实现: touchesBegan ， touchesMoved ， touchesEnded ， touchesCancelled 用于您的相机视图控制器.在 touchesBegan 中，您需要在 UITouch 位置为当前的ARFrame进行 hitTest .然后，您将拥有您的 startPosition 和您的 lastTouch ，这是您的起始 UITouch .

You'll need to implement: touchesBegan, touchesMoved, touchesEnded, touchesCancelled for your camera view controller. In touchesBegan you will need to make hitTest for current ARFrame in the UITouch location. Then you'll have your startPosition and your lastTouch, which is your start UITouch.

然后，您将需要添加间隔为 0.016_667 (60Hz)的计时器，该间隔将在摄像机移动时使用 hitTest 更新您的最后触摸位置.与您在 touchesMoved 函数中所做的相同.在 touchesMoved 中，您还将更新您的 lastTouch .因此，此时您将拥有 startPosition 和 currentPosition ，即 SCNVector3 .如果需要直线，则可以为这些位置重新绘制SCNCylinder(例如，半径为0.001m).

Then you will need to add timer with 0.016_667 interval (60Hz) which will update your last touch position with hitTest when you camera moves. Same you'll do in touchesMoved function. And in touchesMoved you'll also update your lastTouch. So at this point you'll have your startPosition and currentPosition, which is SCNVector3. And you can just redraw SCNCylinder (with 0.001m radius for example) for those positions if you need straight line.

在 touchesEnded 的最后一步，您将修复您的行，或者，如果 touchesCancelled ，您将其删除并清除 lastTouch .

At last step in touchesEnded you'll fix your line, or if touchesCancelled you will remove it and clear lastTouch.

UPD

如果需要在屏幕上显示2D线，则需要对ARSceneView使用 projectPoint .

If you need 2D line on the screen, then you'll need to use projectPoint for your ARSceneView.

3D线条图

要绘制3D线，您可以 SCNGeometry 使用扩展名:

For drawing 3D line you could SCNGeometry use extension:

extension SCNGeometry {
    class func line(from vector1: SCNVector3, to 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])
    }
}

使用:

let line = SCNGeometry.line(from: startPosition, to: endPosition)
let lineNode = SCNNode(geometry: line)
lineNode.position = SCNVector3Zero
sceneView.scene.rootNode.addChildNode(lineNode)

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