outline shader for THREE.js

gistfile1.js

var outline_shader = {
    uniforms: {
        "linewidth":  { type: "f", value: 0.3 },
    },
    vertex_shader: [
        "uniform float linewidth;",
        "void main() {",
            "vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 );",
            "vec4 displacement = vec4( normalize( normalMatrix * normal ) * linewidth, 0.0 ) + mvPosition;",
            "gl_Position = projectionMatrix * displacement;",
        "}"
    ].join("\n"),
    fragment_shader: [
        "void main() {",
            "gl_FragColor = vec4( 0.0, 0.0, 0.0, 1.0 );",
        "}"
    ].join("\n")
};

var outline_material = new THREE.ShaderMaterial({
    uniforms: THREE.UniformsUtils.clone(outline_shader.uniforms),
    vertexShader: outline_shader.vertex_shader,
    fragmentShader: outline_shader.fragment_shader
});