visionOS空间计算实战开发教程Day 8 附属视图和动画

本节我们开始初探在visionOS中添加动画效果，我们的入口文件和ContentView和Day 6中并没有什么区别，所以重点来看ViewModel和ImmersiveView。

首先是ViewModel.swift文件：

import SwiftUI
import RealityKit

class ViewModel: ObservableObject {
    private var contentEntity = Entity()
    
    func setupContentEntity() -> Entity {
        return contentEntity
    }
    
    func getTargetEntity(name: String) -> Entity? {
        return contentEntity.children.first { $0.name == name }
    }
    
    func addCube(name: String, position: SIMD3<Float>, color: UIColor) -> ModelEntity {
        let entity = ModelEntity(
            mesh: .generateBox(size: 0.5, cornerRadius: 0),
            materials: [SimpleMaterial(color: color, isMetallic: false)],
            collisionShape: .generateBox(size: SIMD3<Float>(repeating: 0.5)),
            mass: 0.0
        )
        
        entity.name = name
        entity.position = position
        entity.components.set(InputTargetComponent(allowedInputTypes: .indirect))
        entity.components.set(CollisionComponent(shapes: [ShapeResource.generateBox(size: SIMD3<Float>(repeating: 0.5))], isStatic: true))
        entity.components.set(HoverEffectComponent())
        
        contentEntity.addChild(entity)
        
        return entity
    }
    
    func playAnimation(entity: Entity) {
        let goUp = FromToByAnimation<Transform>(
            name: "goUp",
            from: .init(scale: .init(repeating: 1), translation: entity.position),
            to: .init(scale: .init(repeating: 1), translation: entity.position + .init(x:0 ,y: 0.4, z: 0)),
            duration: 0.2,
            timing: .easeOut,
            bindTarget: .transform
        )
        
        let pause = FromToByAnimation<Transform>(
            name: "pause",
            from: .init(scale: .init(repeating: 1), translation: entity.position + .init(x:0 ,y: 0.4, z: 0)),
            to: .init(scale: .init(repeating: 1), translation: entity.position + .init(x:0 ,y: 0.4, z: 0)),
            duration: 0.1,
            bindTarget: .transform
        )
        
        let goDown = FromToByAnimation<Transform>(
            name: "goDown",
            from: .init(scale: .init(repeating: 1), translation: entity.position + .init(x:0 ,y: 0.4, z: 0)),
            to: .init(scale: .init(repeating: 1), translation: entity.position),
            duration: 0.2,
            timing: .easeOut,
            bindTarget: .transform
        )
        
        let goUpAnimation = try! AnimationResource.generate(with: goUp)
        
        let pauseAnimation = try! AnimationResource.generate(with: pause)
        
        let goDownAnimation = try! AnimationResource.generate(with: goDown)
        
        let animation = try! AnimationResource.sequence(with: [goUpAnimation, pauseAnimation, goDownAnimation])
        
        entity.playAnimation(animation, transitionDuration: 0.5)
    }
}

import SwiftUI

import RealityKit

class ViewModel: ObservableObject {

private var contentEntity = Entity()

func setupContentEntity() -> Entity {

return contentEntity

}

func getTargetEntity(name: String) -> Entity? {

return contentEntity.children.first { $0.name == name }

}

func addCube(name: String, position: SIMD3<Float>, color: UIColor) -> ModelEntity {

let entity = ModelEntity(

mesh: .generateBox(size: 0.5, cornerRadius: 0),

materials: [SimpleMaterial(color: color, isMetallic: false)],

collisionShape: .generateBox(size: SIMD3<Float>(repeating: 0.5)),

mass: 0.0

)

entity.name = name

entity.position = position

entity.components.set(InputTargetComponent(allowedInputTypes: .indirect))

entity.components.set(CollisionComponent(shapes: [ShapeResource.generateBox(size: SIMD3<Float>(repeating: 0.5))], isStatic: true))

entity.components.set(HoverEffectComponent())

contentEntity.addChild(entity)

return entity

}

func playAnimation(entity: Entity) {

let goUp = FromToByAnimation<Transform>(

from: .init(scale: .init(repeating: 1), translation: entity.position),

to: .init(scale: .init(repeating: 1), translation: entity.position + .init(x:0 ,y: 0.4, z: 0)),

duration: 0.2,

timing: .easeOut,

bindTarget: .transform

)

let pause = FromToByAnimation<Transform>(

from: .init(scale: .init(repeating: 1), translation: entity.position + .init(x:0 ,y: 0.4, z: 0)),

to: .init(scale: .init(repeating: 1), translation: entity.position + .init(x:0 ,y: 0.4, z: 0)),

duration: 0.1,

bindTarget: .transform

)

let goDown = FromToByAnimation<Transform>(

from: .init(scale: .init(repeating: 1), translation: entity.position + .init(x:0 ,y: 0.4, z: 0)),

to: .init(scale: .init(repeating: 1), translation: entity.position),

duration: 0.2,

timing: .easeOut,

bindTarget: .transform

)

let goUpAnimation = try! AnimationResource.generate(with: goUp)

let pauseAnimation = try! AnimationResource.generate(with: pause)

let goDownAnimation = try! AnimationResource.generate(with: goDown)

let animation = try! AnimationResource.sequence(with: [goUpAnimation, pauseAnimation, goDownAnimation])

entity.playAnimation(animation, transitionDuration: 0.5)

}

通过前面的学习我们已经知道setupContentEntity用于初始化实体对象，getTargetEntity用于根据模型的名称查找到指定模型。addCube(name: String, position: SIMD3<Float>, color: UIColor)中包含三个参数，name用于指定所创建盒子的名称，position用于指定盒子所处的位置，同样是按人所处位置为参照坐标，color用于指定盒体的颜色。

接下来就是本节的一个重要的知识点了，playAnimation用于创建动画效果，传入的参数entity就是要实现动画效果的模型。

结构体FromToByAnimation可用于实现实体对象和场景的动画，方式为逐渐修改参数值。from值表示动画属性的起始值，to表示动画结束时的属性值，也可以通过by值让框架来计算动画结束时的值。duration顾名思义是指动画的时长，timing参数通过AnimationTimingFunction结构体中的定时函数进行指定，包含的值有：

default：生成默认过渡曲线的定时函数，不指定时此即为默认值。
linear：生成线性过渡效果的定时函数。
easeIn：生成淡入效果的定时函数。
easeOut：生成淡出效果的定时函数。
easeInOut：生成淡入淡出效果的定时函数。

bindTarget参数指定为tranform时表示动画作用于对象本身。

我们定义了三个动画函数，分别为goUp、pause和goDown，实现在纵坐标上完成上下移动0.4个单位的动画效果。接下来通过这三个动画定义来生成动画资源并指定动画的顺序，最后对实体对象调用playAnimation来播放动画，这里的transitionDuration参数与三个动画函数中用时的总和相同。

接下来是我们的ImmersiveView:

import SwiftUI
import RealityKit

struct ImmersiveView: View {
    @State var model = ViewModel()
    @State var cube1 = ModelEntity()
    @State var cube2 = ModelEntity()
        
    var body: some View {
        RealityView { content, attachments in
            content.add(model.setupContentEntity())
            cube1 = model.addCube(name: "Cube1", position: SIMD3<Float>(x: 1, y: 1, z: -2), color: .red)
            cube2 = model.addCube(name: "Cube2", position: SIMD3<Float>(x: -1, y: 1, z: -2), color: .blue)
            
            if let attachment = attachments.entity(for: "cube1_label") {
                attachment.position = [0, -0.35, 0]
                cube1.addChild(attachment)
            }
            
            if let attachment = attachments.entity(for: "cube2_label") {
                attachment.position = [0, -0.35, 0]
                cube2.addChild(attachment)
            }
        } attachments: {
            Attachment(id: "cube1_label") {
                Text("Cube1")
                    .font(.system(size: 48))
            }
            Attachment(id: "cube2_label") {
                Text("Cube2")
                    .font(.system(size: 48))
            }
        }
        .gesture(
            SpatialTapGesture()
                .targetedToEntity(cube1)
                .onEnded { value in
                    print(value)
                    model.playAnimation(entity: cube1)
                }
        )
        .gesture(
            SpatialTapGesture()
                .targetedToEntity(cube2)
                .onEnded { value in
                    print(value)
                    model.playAnimation(entity: cube2)
                }
        )
    }
}

import SwiftUI

import RealityKit

struct ImmersiveView: View {

@State var model = ViewModel()

@State var cube1 = ModelEntity()

@State var cube2 = ModelEntity()

var body: some View {

RealityView { content, attachments in

content.add(model.setupContentEntity())

cube1 = model.addCube(name: "Cube1", position: SIMD3<Float>(x: 1, y: 1, z: -2), color: .red)

cube2 = model.addCube(name: "Cube2", position: SIMD3<Float>(x: -1, y: 1, z: -2), color: .blue)

if let attachment = attachments.entity(for: "cube1_label") {

attachment.position = [0, -0.35, 0]

cube1.addChild(attachment)

}

if let attachment = attachments.entity(for: "cube2_label") {

attachment.position = [0, -0.35, 0]

cube2.addChild(attachment)

}

} attachments: {

Attachment(id: "cube1_label") {

Text("Cube1")

.font(.system(size: 48))

}

Attachment(id: "cube2_label") {

Text("Cube2")

.font(.system(size: 48))

}

.gesture(

SpatialTapGesture()

.targetedToEntity(cube1)

.onEnded { value in

print(value)

model.playAnimation(entity: cube1)

}

)

.gesture(

SpatialTapGesture()

.targetedToEntity(cube2)

.onEnded { value in

print(value)

model.playAnimation(entity: cube2)

}

)

}

cube1为红色，位于我们的右侧，cube2为蓝色，位于我们的左侧，为方便标识，我们通过RealityView的AttachmentContentBuilder（即attachments参数）来创建附属视图，但附属视图并不会自动添加到RealityView的对象上。我们需要显式地进行指定，这里attachments.entity中的for与Attachment的id相对应，我们只添加了两个文本视图，并通过position指定了相对于父对象的位置。

接着通过SpatialTapGesture指定在点击相应盒子时执行前面所定义的playAnimation。

运行应用，点击Show ImmersiveSpace会显示两个盒子，盒子下方分别显示一个附属视图，点击盒体会执行上下移动的动画。

visionOS空间计算实战开发教程Day 8 附属视图和动画