上一篇博客我们了解了自定义点绘制，这篇我们接着学习cesium自定义绘制线。点和线的绘制，流程一样，只是设置的属性不一样。只需要注意下面地方：
1、CreateGeometry函数中设置PrimitiveType
image.png
2、计算顶点索引（坐标点下标的相连顺序）
image.png
直接上代码：
var viewer = new Cesium.Viewer('cesiumContainer');
//封装PrimitivePolyline
var PrimitivePolyline=(
function () {
var vertexShader;
var fragmentShader;
//var geometry;
//var appearance;
var viewer;
function _(options) {
viewer = options.viewer;
vertexShader = getVS();
fragmentShader = getFS();
if (options.Cartesians && options.Cartesians.length >= 2) {
var postionsTemp = [];
var colorsTemp = [];
var indicesTesm = [];
if (options.Colors && options.Colors.length === options.Cartesians.length * 4) {
for (var i = 0; i < options.Cartesians.length; i++) {
postionsTemp.push(options.Cartesians[i].x);
postionsTemp.push(options.Cartesians[i].y);
postionsTemp.push(options.Cartesians[i].z);
}
colorsTemp = options.Colors;
} else {
for (var i = 0; i < options.Cartesians.length; i++) {
postionsTemp.push(options.Cartesians[i].x);
postionsTemp.push(options.Cartesians[i].y);
postionsTemp.push(options.Cartesians[i].z);
//
colorsTemp.push(0.0);
colorsTemp.push(0.0);
colorsTemp.push(1.0);
colorsTemp.push(1.0);
}
}
for (var i = 1; i < options.Cartesians.length; i++) {
indicesTesm.push(i - 1);
indicesTesm.push(i);
}
this.positionArr = new Float64Array(postionsTemp);
this.colorArr = new Float32Array(colorsTemp);
this.indiceArr = new Uint16Array(indicesTesm);
} else {
var p1 = Cesium.Cartesian3.fromDegrees(0, 0, -10);
var p2 = Cesium.Cartesian3.fromDegrees(0, 0.001, -10);
this.positionArr = new Float64Array([
p1.x, p1.y, p1.z,
p2.x, p2.y, p2.z
]);
//默认蓝色
this.colorArr = new Float32Array([
0.0, 0.0, 1.0, 1.0,
0.0, 0.0, 1.0, 1.0
]);
this.indiceArr = new Uint16Array([0, 1]);
}
this.geometry = CreateGeometry(this.positionArr, this.colorArr, this.indiceArr);
this.appearance = CreateAppearence(fragmentShader, vertexShader);
this.primitive = viewer.scene.primitives.add(new Cesium.Primitive({
geometryInstances: new Cesium.GeometryInstance({
geometry: this.geometry
}),
appearance: this.appearance,
asynchronous: false
}));
}
function CreateGeometry(positions, colors, indices) {
return new Cesium.Geometry({
attributes: {
position: new Cesium.GeometryAttribute({
componentDatatype: Cesium.ComponentDatatype.DOUBLE,
componentsPerAttribute: 3,
values: positions
}),
color: new Cesium.GeometryAttribute({
componentDatatype: Cesium.ComponentDatatype.FLOAT,
componentsPerAttribute: 4,
values: colors
})
},
indices: indices,
primitiveType: Cesium.PrimitiveType.LINES,
boundingSphere: Cesium.BoundingSphere.fromVertices(positions)
});
}
function CreateAppearence(fs, vs) {
return new Cesium.Appearance({
renderState: {
blending: Cesium.BlendingState.PRE_MULTIPLIED_ALPHA_BLEND,
depthTest: { enabled: true },
depthMask: true,
lineWidth: 1.0
},
fragmentShaderSource: fs,
vertexShaderSource: vs
});
}
function getVS() {
return "attribute vec3 position3DHigh;\
attribute vec3 position3DLow;\
attribute vec4 color;\
varying vec4 v_color;\
attribute float batchId;\
void main()\
{\
vec4 p = czm_computePosition();\
v_color =color;\
p = czm_modelViewProjectionRelativeToEye * p;\
gl_Position = p;\
}\
";
}
function getFS() {
return "varying vec4 v_color;\
void main()\
{\
gl_FragColor =v_color;\
}\
";
}
_.prototype.remove = function () {
if (this.primitive != null) {
viewer.scene.primitives.remove(this.primitive);
this.positionArr = null;
this.colorArr = null;
this.indiceArr = null;
this.geometry = null;
this.appearance = null;
this.primitive = null;
}
}
_.prototype.updateCartesianPosition = function (cartesians) {
if (this.primitive != null) {
viewer.scene.primitives.remove(this.primitive);
if (cartesians && cartesians.length < 2) { return; }
//默认蓝色
var postionsTemp = [];
var colorsTemp = [];
var indicesTesm = [];
for (var i = 0; i < cartesians.length; i++) {
postionsTemp.push(cartesians[i].x);
postionsTemp.push(cartesians[i].y);
postionsTemp.push(cartesians[i].z);
colorsTemp.push(0.0);
colorsTemp.push(0.0);
colorsTemp.push(1.0);
colorsTemp.push(1.0);
}
for (var i = 1; i < cartesians.length; i++) {
indicesTesm.push(i - 1);
indicesTesm.push(i);
}
this.positionArr = new Float64Array(postionsTemp);
this.colorArr = new Float32Array(colorsTemp);
this.indiceArr = new Uint16Array(indicesTesm);
this.geometry = CreateGeometry(this.positionArr, this.colorArr, this.indiceArr);
this.appearance = CreateAppearence(fragmentShader, vertexShader);
this.primitive = viewer.scene.primitives.add(new Cesium.Primitive({
geometryInstances: new Cesium.GeometryInstance({
geometry: this.geometry
}),
appearance: this.appearance,
asynchronous: false
}));
} else { return;}
}
_.prototype.updateCartesianPositionColor = function (cartesians, colors) {
if (colors.length === cartesians.length * 4) { } else { return; }
if (this.primitive != null) {
viewer.scene.primitives.remove(this.primitive);
if (cartesians && cartesians.length < 2) { return; }
var postionsTemp = [];
var indicesTesm = [];
for (var i = 0; i < cartesians.length; i++) {
postionsTemp.push(cartesians[i].x);
postionsTemp.push(cartesians[i].y);
postionsTemp.push(cartesians[i].z);
}
for (var i = 1; i < cartesians.length; i++) {
indicesTesm.push(i - 1);
indicesTesm.push(i);
}
this.positionArr = new Float64Array(postionsTemp);
this.colorArr = new Float32Array(colors);
this.indiceArr = new Uint16Array(indicesTesm);
this.geometry = CreateGeometry(this.positionArr, this.colorArr, this.indiceArr);
this.appearance = CreateAppearence(fragmentShader, vertexShader);
this.primitive = viewer.scene.primitives.add(new Cesium.Primitive({
geometryInstances: new Cesium.GeometryInstance({
geometry: this.geometry
}),
appearance: this.appearance,
asynchronous: false
}));
} else { return; }
}
return _;
})();
//定义要显示的点坐标（经纬度）
var positions = new Float64Array([
110.2, 20.6,
110.2, 21.9,
111, 23
]);
var cartesian3Positions = Cesium.Cartesian3.fromDegreesArray(positions);
//定义要显示的点的颜色（4个元素定义一个点的颜色（红绿蓝透明度））
var Colors = new Float64Array([
1.0,0.0,0.0,1.0,
0.0,1.0,0.0,1.0,
0.0,0.0,1.0,1.0
]);
var p = new PrimitivePolyline({
viewer:viewer,
Cartesians:cartesian3Positions,
Colors:Colors
});
image.png
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