如何在 RealityKit 中使用 Raycast 方法？

Question

RealityKit框架中有3种检测交点的方法，但我不知道如何在我的项目中使用。

1.

func raycast(origin: SIMD3<Float>, 
          direction: SIMD3<Float>, 
             length: Float, 
              query: CollisionCastQueryType, 
               mask: CollisionGroup, 
         relativeTo: Entity?) -> [CollisionCastHit]

2.

func raycast(from: SIMD3<Float>, 
               to: SIMD3<Float>, 
            query: CollisionCastQueryType, 
             mask: CollisionGroup, 
       relativeTo: Entity?) -> [CollisionCastHit]

3.

func convexCast(convexShape: ShapeResource, 
               fromPosition: SIMD3<Float>, 
            fromOrientation: simd_quatf, 
                 toPosition: SIMD3<Float>, 
              toOrientation: simd_quatf, 
                      query: CollisionCastQueryType, 
                       mask: CollisionGroup, 
                 relativeTo: Entity?) -> [CollisionCastHit]

Answer 1

简单的光线投射

If you want to find out how to position a model made in Reality Composer into a RealityKit scene (that has a detected horizontal plane) using Ray-Casting method, use the following code:

import RealityKit
import ARKit

class ViewController: UIViewController {
    
    @IBOutlet var arView: ARView!
    let scene = try! Experience.loadScene()
    
    @IBAction func onTap(_ sender: UITapGestureRecognizer) {
        
        scene.steelBox!.name = "Parcel"
        
        let tapLocation: CGPoint = sender.location(in: arView)
        let estimatedPlane: ARRaycastQuery.Target = .estimatedPlane
        let alignment: ARRaycastQuery.TargetAlignment = .horizontal
                
        let result: [ARRaycastResult] = arView.raycast(from: tapLocation,
                                                   allowing: estimatedPlane,
                                                  alignment: alignment)
        
        guard let rayCast: ARRaycastResult = result.first
        else { return }
        
        let anchor = AnchorEntity(world: rayCast.worldTransform)
        anchor.addChild(scene)
        arView.scene.anchors.append(anchor)
        
        print(rayCast)
    }
}

关注一个classARRaycastQuery。这个class来自ARKit，不是来自RealityKit。

凸射线投射

A Convex-Ray-Casting methods like raycast(from:to:query:mask:relativeTo:) is the op of swiping a convex shapes along a straight line and stopping at the very first intersection with any of the collision shape in the scene. Scene raycast() method performs a hit-tests against all entities with collision shapes in the scene. Entities without a collision shape are ignored.

您可以使用以下代码从开始位置到结束执行凸射线投射：

import RealityKit

let startPosition: SIMD3<Float> = [0, 0, 0]
let endPosition: SIMD3<Float> = [5, 5, 5]
let query: CollisionCastQueryType = .all
let mask: CollisionGroup = .all

let raycasts: [CollisionCastHit] = arView.scene.raycast(from: startPosition, 
                                                          to: endPosition, 
                                                       query: query,  
                                                        mask: mask, 
                                                  relativeTo: nil)

guard let rayCast: CollisionCastHit = raycasts.first
else { return }
    
print(rayCast.distance)      /* The distance from the ray origin to the hit */
print(rayCast.entity.name)   /* The entity's name that was hit              */

一个CollisionCastHit结构是碰撞投射的命中结果，它存在于RealityKit的场景中。

P.S.

When you use raycast(from:to:query:mask:relativeTo:) method for measuring a distance from camera to entity it doesn't matter what an orientation of ARCamera is, it only matters what its position is in world coordinates.

如何在 RealityKit 中使用 Raycast 方法？

How to use Raycast methods in RealityKit?

augmented-reality

raycasting

swift

arkit

realitykit

简单的光线投射

凸射线投射