原理：利用polygon的extrudedHeight屬性，動態增加（原理很簡單，但效果挺好）

效果圖：

核心程式碼：

	_drawWater(targetHeight, adapCoordi) {
		// this.earth.entities.remove(this.waterEntities)
		let entity = this.earth.entities.add({
			polygon: {
				hierarchy: Cesium.Cartesian3.fromDegreesArrayHeights(adapCoordi),
				material: new GV.Color.fromBytes(64, 157, 253, 150),
				perPositionHeight: true,
				extrudedHeight: 0.0,
				// closeBottom:false
			}
		})
		this.waterEntities = entity
		let waterHeight = adapCoordi[2]
		// this.earth.clock.onTick.addEventListener((clock)=> {
		//     waterHeight++
		//     entity.polygon.extrudedHeight.setValue(waterHeight)
		// })
		this.timer = setInterval(() => {
			if (waterHeight < targetHeight) {
				waterHeight += 100
				if (waterHeight > targetHeight) {
					waterHeight = targetHeight
				}
				entity.polygon.extrudedHeight.setValue(waterHeight)
			}
		}, 100)
		this.entities.push(entity)
	}