// 爆炸
export function createBlast(viewer, obj, o) {
    createParticle(viewer, obj, o, 101)
}

// 喷泉
export function createFountain(viewer, obj, o) {
    createParticle(viewer, obj, o, 103)
}

// 烟花
export function createFireworks(viewer, obj, o) {
    createParticle(viewer, obj, o, 104)
}

// 粒子的生成方法
export function createParticle(viewer, obj, o, type) {
    viewer.clock.shouldAnimate = true
    let entity = viewer.entities.add({
        position: Cesium.Cartesian3.fromDegrees(o.position[0], o.position[1], Number(o.position[2] + o.height)),
        id: o.id
    })
    let emitter
    if (o.typevalue == '圆形放射') {
        if (type == 103) {
            emitter = new Cesium.CircleEmitter(0.2)
        } else if (type == 104) {
            emitter = new Cesium.CircleEmitter(5.0)
        } else if (type == 101) {
            emitter = new Cesium.CircleEmitter(0.1)
        }
    } else if (o.typevalue == '球体放射') {
        if (type == 103) {
            emitter = new Cesium.SphereEmitter(2.5)
        } else if (type == 101 || type == 104) {
            emitter = new Cesium.SphereEmitter(0.1)
        }
    } else if (o.typevalue == '圆锥体放射') {
        emitter = new Cesium.ConeEmitter(
            Cesium.Math.toRadians(45.0)
        )
    } else if (o.typevalue == '盒状放射') {
        if (type == 101) {
            emitter = new Cesium.BoxEmitter(
                new Cesium.Cartesian3(0.1, 0.1, 0.1)
            )
        } else {
            emitter = new Cesium.BoxEmitter(
                new Cesium.Cartesian3(10.0, 10.0, 10.0)
            )
        }
    }

    let particleCanvas
    function getImage() {
        if (!Cesium.defined(particleCanvas)) {
            particleCanvas = document.createElement("canvas")
            particleCanvas.width = 20
            particleCanvas.height = 20
            const context2D = particleCanvas.getContext("2d")
            context2D.beginPath()
            context2D.arc(8, 8, 8, 0, Cesium.Math.TWO_PI, true)
            context2D.closePath()
            context2D.fillStyle = "rgb(255, 255, 255)"
            context2D.fill()
        }
        return particleCanvas;
    }
    
    let img, startColor, endColor, bursts, lifetime
    if (type == 101) {
        img = require('../image/Blast.png')
        startColor = new Cesium.Color(1, 1, 1, 0.3).withAlpha(1)
        endColor = new Cesium.Color(0.8, 0.86, 1, 0.4).withAlpha(0)
        lifetime = 8
        bursts = undefined
    } else if  (type == 103) {
        img = require('../image/fountain.png')
        startColor = new Cesium.Color(1, 1, 1, 0.3)
        endColor = new Cesium.Color(0.8, 0.86, 1, 0.4)
        bursts = undefined
        lifetime = 16
    } else if (type == 104) {
        img = getImage()
        startColor = Cesium.Color.fromCssColorString(o.fireworkColor).withAlpha(1)
        endColor = Cesium.Color.fromCssColorString(o.fireworkColor).withAlpha(0)
        lifetime = 2
        bursts = []
        for (let j = 0; j < 3; ++j) {
            bursts.push(
                new Cesium.ParticleBurst({
                    // time: 0,
                    time: Cesium.Math.nextRandomNumber() * 2,
                    minimum: 400.0,
                    maximum: 400.0
                })
            )
        }
    }

    let particleSystem = viewer.scene.primitives.add(
        new Cesium.ParticleSystem({
            id: o.id,
            image: img, // 粒子的图片
            startColor: startColor, // 起始颜色
            endColor: endColor, // 结束颜色
            startScale: o.startScale, // 开始大小比例
            endScale: o.endScale, // 结束大小比例
            minimumParticleLife: o.minimumParticleLife, // 最小生命周期
            maximumParticleLife: o.maximumParticleLife, // 最大生命周期
            minimumSpeed: o.minimumSpeed, // 最小速度
            maximumSpeed: o.maximumSpeed, // 最大速度
            bursts: bursts,
            imageSize: new Cesium.Cartesian2(
                o.particleSize,
                o.particleSize * 2
            ), // 粒子大小
            emissionRate: o.emissionRate, // 粒子数量
            lifetime: lifetime,
            loop: true, // 循环是否开启
            emitter: emitter, // 粒子的释放方向
            updateCallback: applyGravity, // 重力回调
            sizeInMeters: true, // 是否以米为单位
        })
    )

    let gravityScratch = new Cesium.Cartesian3()
    function applyGravity(p, dt) {
        let position = p.position
        Cesium.Cartesian3.normalize(position, gravityScratch)
        Cesium.Cartesian3.multiplyByScalar(
            gravityScratch,
            o.gravity * dt,
            gravityScratch
        )
        p.velocity = Cesium.Cartesian3.add(
            p.velocity,
            gravityScratch,
            p.velocity
        )
    }

    viewer.scene.preUpdate.addEventListener(function (scene, time) {
        particleSystem.modelMatrix = computeModelMatrix(entity, time)
        particleSystem.emitterModelMatrix = computeEmitterModelMatrix()
    })
 
    function computeModelMatrix(entity, time) {
        return entity.computeModelMatrix(time, new Cesium.Matrix4())
    }
 
    let emitterModelMatrix = new Cesium.Matrix4()
    let translation = new Cesium.Cartesian3()
    let rotation = new Cesium.Quaternion()
    let hpr = new Cesium.HeadingPitchRoll()
    let trs = new Cesium.TranslationRotationScale()

    // 改变粒子系统的位置
    function computeEmitterModelMatrix() {
        hpr = Cesium.HeadingPitchRoll.fromDegrees(0.0, 0.0, 0.0, hpr)
        trs.translation = Cesium.Cartesian3.fromElements(0, 0, 0, translation)
        trs.rotation = Cesium.Quaternion.fromHeadingPitchRoll(hpr, rotation)
        return Cesium.Matrix4.fromTranslationRotationScale(
            trs,
            emitterModelMatrix
        )
    }
}