CappingEffect.h

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#pragma once
 
#include <osgFX/Effect>
#include <osg/Geometry>
#include <osg/Stencil>
#include <osg/Depth>
#include <osg/Projection>
#include <osg/PolygonMode>
 
class CappingTechnique : public osgFX::Technique {
 
private:
    osg::ref_ptr<osg::Node> _capPlane;
 
public:
    virtual bool validate(osg::State&) const
    { return true; }
 
    META_Technique("CappingTechnique","Pimpel capping technique");
    CappingTechnique()
    {
        // Build the plane to draw with the stencil mask
        osg::Geometry *geometry = new osg::Geometry();
        osg::Vec3Array *vertices = new osg::Vec3Array();
        osg::Vec3Array *normals = new osg::Vec3Array();
        osg::Vec4Array *colors = new osg::Vec4Array();
 
        vertices->push_back(osg::Vec3(-10.0, -10.0, 0.1));
        vertices->push_back(osg::Vec3(-10.0, 10.0, 0.1));
        vertices->push_back(osg::Vec3(10.0, 10.0, 0.1));
        vertices->push_back(osg::Vec3(10.0, -10.0, 0.1));
        normals->push_back(osg::Vec3(0.0, 0.0, 1.0));
        geometry->setVertexArray(vertices);
        geometry->setNormalArray(normals);
        colors->push_back(osg::Vec4(1.0, 0.0, 1.0, 1.0));
        geometry->setColorArray(colors);
        geometry->setColorBinding(osg::Geometry::BIND_OVERALL);
        geometry->setNormalBinding(osg::Geometry::BIND_OVERALL);
        geometry->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::QUADS, 0, 4));
 
        osg::Geode *geode = new osg::Geode();
        geode->addDrawable(geometry);
        geode->getOrCreateStateSet()->setMode(GL_DEPTH_TEST, osg::StateAttribute::ON);
 
        _capPlane = geode;
        return;
 
        osg::Transform *trans = new osg::Transform();
        trans->setReferenceFrame( osg::Transform::ABSOLUTE_RF );
        trans->addChild( geode );
 
        osg::Projection *proj = new osg::Projection(osg::Matrix::ortho2D(-1,1,-1,1));
        proj->addChild( trans );
 
        _capPlane = proj;
 
    }
protected:
    virtual void define_passes()
    {
        // pass #0
        {
            osg::ref_ptr<osg::StateSet> ss = new osg::StateSet;
            osg::Stencil *stencil = new osg::Stencil;
            stencil->setFunction(osg::Stencil::ALWAYS, 0x0, ~0);
            stencil->setOperation(osg::Stencil::INVERT, osg::Stencil::INVERT, osg::Stencil::INVERT);
            ss->setAttributeAndModes(stencil, osg::StateAttribute::ON); // | osg::StateAttribute::OVERRIDE);
            ss->setMode(GL_CULL_FACE,osg::StateAttribute::OFF | osg::StateAttribute::OVERRIDE);
            addPass(ss.get());
        }
        // pass #1
        {
            osg::ref_ptr<osg::StateSet> ss = new osg::StateSet;
            osg::Stencil *stencil = new osg::Stencil;
            stencil->setFunction(osg::Stencil::NOTEQUAL, 0x0, ~0);
            stencil->setOperation(osg::Stencil::ZERO, osg::Stencil::ZERO,osg::Stencil::ZERO);
            ss->setAttributeAndModes(stencil, osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE);
            ss->setMode(GL_CLIP_PLANE0, osg::StateAttribute::OFF);
            osg::Depth *depth = new osg::Depth();
            depth->setWriteMask(true);
            ss->setAttributeAndModes( depth, osg::StateAttribute::ON);
            ss->setMode(GL_CULL_FACE,osg::StateAttribute::OFF | osg::StateAttribute::OVERRIDE);
            ss->setAttributeAndModes(new osg::PolygonMode(osg::PolygonMode::FRONT_AND_BACK, osg::PolygonMode::FILL));
            ss->setMode(GL_CLIP_PLANE0, osg::StateAttribute::OFF | osg::StateAttribute::OVERRIDE);
            addPass(ss.get());
        }
    }
 
    virtual osg::Node *getOverrideChild(int pass){
        switch(pass) {
        case 1: // Second pass (pass #1) draws the cap plane
            return _capPlane;
            break;
        default:
            return NULL;
            break;
        }
    }
};
 
class CappingEffect : public osgFX::Effect {
public:
    CappingEffect() : osgFX::Effect() {}
    CappingEffect( const CappingEffect& copy, const osg::CopyOp op=osg::CopyOp::SHALLOW_COPY )
        : osgFX::Effect(copy, op) {}
 
    META_Effect( osgFX, CappingEffect, "CappingEffect", "", "" );
protected:
    virtual bool define_techniques(){
        CappingTechnique* technique = new CappingTechnique();
        addTechnique(technique);
        return true;
    }
};