GLSL model outline for osgEarth VP

gistfile1.txt

/* -*-c++-*- */
/* osgEarth - Dynamic map generation toolkit for OpenSceneGraph
* Copyright 2015 Pelican Mapping
* http://osgearth.org
*
* osgEarth is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program.  If not, see <http://www.gnu.org/licenses/>
*/

#include <osgViewer/Viewer>
#include <osg/Depth>
#include <osgDB/ReadFile>
#include <osgEarth/Registry>

#define LC "[viewer] "

using namespace osgEarth;

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

    osg::Node* node = osgDB::readNodeFiles(arguments);

    Registry::shaderGenerator().run(node);

    const char* VS = 
        "#version 330 compatibility\n"
        "const float outline = 0.002; \n"
        "vec3 vp_Normal;\n"
        "void VS(inout vec4 clip) {\n"
        "    vec3 n = normalize(vp_Normal); \n"
        "    n.x *= gl_ProjectionMatrix[0][0];\n"
        "    n.y *= gl_ProjectionMatrix[1][1];\n"
        "    clip.xy += n.xy * clip.w * outline;\n"
        "}\n";

    const char* FS =
        "#version 330\n"
        "void FS(inout vec4 color) { \n"
        "    color = vec4(1,0,0,color.a);\n"
        "}\n";

    osg::Group* outline = new osg::Group();
    osg::StateSet* outlineSS = outline->getOrCreateStateSet();
    outlineSS->setRenderBinDetails(10, "RenderBin");
    outlineSS->setAttributeAndModes(new osg::Depth(osg::Depth::LESS, 0.0, 1.0, false));
    outlineSS->setMode(GL_CULL_FACE, 0);
    VirtualProgram* vp = VirtualProgram::getOrCreate(outlineSS);
    vp->setFunction("VS", VS, ShaderComp::LOCATION_VERTEX_CLIP);
    vp->setFunction("FS", FS, ShaderComp::LOCATION_FRAGMENT_COLORING);   
    outline->addChild(node);
    
    osg::Group* model = new osg::Group();
    model->getOrCreateStateSet()->setRenderBinDetails(20, "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();
}