Cesium 创建Geometry

var viewer = new Cesium.Viewer('cesiumContainer', {
			navigationHelpButton: false,
			animation: false,
			timeline: false
		});
		//坐标
		var mypositions = Cesium.Cartesian3.fromDegreesArrayHeights([
			// Triangle A
			-90.6714, 35.9641, 322.543, -94.6717, 38.9642, 325.51, -97.6717, 35.9639, 324.724,
			// Triangle B
			-94.6717, 30.9639, 324.717, -90.6717, 32.9639, 324.724, -94.6717, 34.9639, 324.719
		]);
		//加入点
		var pointCollection = new Cesium.PointPrimitiveCollection();
		for (var i = 0; i < mypositions.length; i++) {
			pointCollection.add({
				position: mypositions[i],
				color: Cesium.Color.YELLOW
			})
		};
		viewer.scene.primitives.add(pointCollection);
		//固定相机位置
		var extent = Cesium.Rectangle.fromDegrees(-98, 30, -90, 39);
		Cesium.Camera.DEFAULT_VIEW_RECTANGLE = extent;
		Cesium.Camera.DEFAULT_VIEW_FACTOR = 0.5;
		
		//点的数量
		var numPositions = mypositions.length;
		//点存储空间
		var pos = new Float64Array(numPositions * 3);
		//向量存储空间
		var normals = new Float32Array(numPositions * 3);
		for (var i = 0; i < numPositions; ++i) {
			pos[i * 3] = mypositions[i].x;
			pos[i * 3 + 1] = mypositions[i].y;
			pos[i * 3 + 2] = mypositions[i].z;
			normals[i * 3] = 0.0;
			normals[i * 3 + 1] = 0.0;
			normals[i * 3 + 2] = 1.0;
		}
		//创建geometry
		var geometry = new Cesium.Geometry({
			attributes: {
				position: new Cesium.GeometryAttribute({
					// not FLOAT
					componentDatatype: Cesium.ComponentDatatype.DOUBLE, 
					componentsPerAttribute: 3,
					values: pos
				}),
				normal: new Cesium.GeometryAttribute({
					componentDatatype: Cesium.ComponentDatatype.FLOAT,
					componentsPerAttribute: 3,
					values: normals
				})
			},
			primitiveType: Cesium.PrimitiveType.TRIANGLES,
			boundingSphere: Cesium.BoundingSphere.fromVertices(pos)
		});
		//绘制三角带
		var myInstance = new Cesium.GeometryInstance({
			geometry: geometry,
			attributes: {
				color: Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.RED)
			},
			show: new Cesium.ShowGeometryInstanceAttribute(true)
		});
		viewer.scene.primitives.add(new Cesium.Primitive({
			geometryInstances: [myInstance],
			asynchronous: false,
			appearance: new Cesium.PerInstanceColorAppearance({
				closed: true,
				translucent: false
			})
		}));