GLSL model outline for OSG

gistfile1.txt

#include <osgViewer/Viewer>
#include <osg/Depth>
#include <osg/Program>
#include <osg/Uniform>
#include <osgDB/ReadFile>

int
main(int argc, char** argv)
{
    osg::ArgumentParser arguments(&argc,argv);

    osg::Node* node = osgDB::readNodeFiles(arguments);
    if ( !node )
        return -1;

    const char* VS = 
        "#version 330 compatibility \n"
        "uniform float outlineWidth; \n"
        "void main()"
        "{ \n"
        "    vec4 clip = gl_ModelViewProjectionMatrix * gl_Vertex; \n"
        "    vec3 normal = normalize(gl_NormalMatrix * gl_Normal); \n"
        "    normal.x *= gl_ProjectionMatrix[0][0]; \n"
        "    normal.y *= gl_ProjectionMatrix[1][1]; \n"
        "    clip.xy += normal.xy * clip.w * outlineWidth;\n"
        "    gl_Position = clip; \n"
        "} \n";

    const char* FS =
        "#version 330\n"
        "void main() \n"
        "{ \n"
        "    gl_FragColor = vec4(1,0,0,1); \n"
        "} \n";

    osg::Program* program = new osg::Program();
    program->addShader(new osg::Shader(osg::Shader::VERTEX, VS));
    program->addShader(new osg::Shader(osg::Shader::FRAGMENT, FS));

    osg::Group* outline = new osg::Group();
    osg::StateSet* outlineSS = outline->getOrCreateStateSet();
    outlineSS->setRenderBinDetails(1, "RenderBin");
    outlineSS->setAttributeAndModes(new osg::Depth(osg::Depth::LESS, 0.0, 1.0, false));
    outlineSS->setMode(GL_CULL_FACE, 0);
    outlineSS->setAttribute(program);
    outlineSS->addUniform(new osg::Uniform("outlineWidth", 0.002f));
    outline->addChild(node);
    
    osg::Group* model = new osg::Group();
    model->getOrCreateStateSet()->setRenderBinDetails(2, "RenderBin");
    model->addChild(node); 

    osg::Group* root = new osg::Group();
    root->addChild(outline);
    root->addChild(model);

    osgViewer::Viewer viewer(arguments);
    viewer.setSceneData(root);

    return viewer.run();
}