RealityKit 如何模拟一个球的飞行,并画出飞行轨迹
在 RealityKit 中模拟一个球的飞行并画出飞行轨迹,可以通过以下步骤实现:
以下是一个示例代码,展示了如何实现这些步骤:
import UIKit
import RealityKit
import ARKit
class ViewController: UIViewController {
@IBOutlet var arView: ARView!
var ballEntity: ModelEntity!
var trajectoryPoints: [SIMD3<Float>] = []
var trajectoryEntity: Entity!
override func viewDidLoad() {
super.viewDidLoad()
// 配置 AR 会话
let config = ARWorldTrackingConfiguration()
arView.session.run(config)
// 创建球体实体
let ballMesh = MeshResource.generateSphere(radius: 0.05)
let ballMaterial = SimpleMaterial(color: .red, isMetallic: false)
ballEntity = ModelEntity(mesh: ballMesh, materials: [ballMaterial])
// 设置球体初始位置
ballEntity.position = SIMD3<Float>(0, 0, -0.5)
// 添加物理属性
ballEntity.physicsBody = PhysicsBodyComponent(massProperties: .init(mass: 1.0), material: .default, mode: .dynamic)
// 添加球体到场景
let anchorEntity = AnchorEntity(world: .zero)
anchorEntity.addChild(ballEntity)
arView.scene.addAnchor(anchorEntity)
// 创建轨迹实体
trajectoryEntity = Entity()
arView.scene.addAnchor(AnchorEntity(world: .zero)).addChild(trajectoryEntity)
// 给球体一个初始速度
let initialVelocity = SIMD3<Float>(0, 1, -1)
ballEntity.physicsBody?.mode = .dynamic
ballEntity.physicsBody?.linearVelocity = initialVelocity
// 开始更新循环
arView.scene.subscribe(to: SceneEvents.Update.self) { event in
self.update(event: event)
}.store(in: &cancellables)
}
var cancellables: [Cancellable] = []
func update(event: SceneEvents.Update) {
// 记录球体位置
let currentPosition = ballEntity.position
trajectoryPoints.append(currentPosition)
// 绘制轨迹
drawTrajectory()
}
func drawTrajectory() {
// 移除之前的轨迹
trajectoryEntity.children.removeAll()
// 创建新的轨迹
let lineMesh = MeshResource.generatePolyline(trajectoryPoints)
let lineMaterial = SimpleMaterial(color: .blue, isMetallic: false)
let lineEntity = ModelEntity(mesh: lineMesh, materials: [lineMaterial])
// 添加轨迹到实体
trajectoryEntity.addChild(lineEntity)
}
}
extension MeshResource {
static func generatePolyline(_ points: [SIMD3<Float>]) -> MeshResource {
var vertices: [MeshResource.Vertex] = []
for point in points {
vertices.append(MeshResource.Vertex(position: point, normal: [0, 0, 1], uv: [0, 0]))
}
let indices = Array(0..<vertices.count)
return MeshResource.generate(from: vertices, indices: indices, primitiveType: .line)
}
}
MeshResource.generateSphere
创建一个球体,并设置其初始位置和物理属性。PhysicsBodyComponent
,并设置初始速度。MeshResource.generatePolyline
方法生成线条,并将其添加到场景中。通过这些步骤,你可以在 RealityKit 中模拟一个球的飞行并绘制其飞行轨