Javascript three.js，通过着色器绘制虚线

我试图为我的虚线制作一个着色器；但我唯一能得到的是从原点到+也许是x方向

如果我渲染这条曲线Ellipse.curve，它们会很好。和着色器不

当然，我不知道为什么。。请帮帮我

    <script type="x-shader/x-vertex" id="vs-orbit">
        uniform float time;
        attribute float sovereign;
        varying vec3 vColor;

        vec3 setColorBySovereign() {
            vec3 color;

            color.r = 0.5 - ( 0.5 * sovereign );
            color.g = 0.25 + ( 0.25 * sovereign );
            color.b = 0.5 + ( 0.25 * sovereign );

            return _color;
        };

        void main() {
            vColor = setColorBySovereign();
            gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
        };
    </script>
    <script type="x-shader/x-fragment" id="fs-orbit">
        attribute vec3 vColor;

        void main() {
            gl_FragColor = vec4(vColor, 1.0);
        };
    </script>

// ... Below is where use shader above;

Ellipse.prototype.createOrbit = function( soveregin ) {
    var shape, mater;
    var sov = soveregin || 0.0;

    shape = new THREE.Geometry();
        var v2;
        for(var i=0; i<721; i++) {
            v2 = this.curve.getPoint(i);
            shape.vertices.push(new THREE.Vector3(v2.x, v2.y, 0));
        };
        shape.computeLineDistances();

    mater = new THREE.ShaderMaterial({
        attribute: { soveregin: sov },
        vertexShader: document.getElementById('vs-orbit'),
        fragmentShader: document.getElementById('fs-orbit')
    });

    this.orbit = new THREE.Line( shape, mater, THREE.LineStrip );
    return;
}

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我解决这个问题；在main{}之后，我不应该使用“；”还有其他语法错误

在片段着色器中，我必须使用操作符“variable”声明vColor，就像顶点着色器一样。在片段着色器中；来自GLSL参考；可变等于in运算符