365 lines
13 KiB
C++
365 lines
13 KiB
C++
/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
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*
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* This application is open source and may be redistributed and/or modified
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* freely and without restriction, both in commericial and non commericial applications,
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* as long as this copyright notice is maintained.
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*
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* This application is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#include <osg/Node>
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#include <osg/Geometry>
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#include <osg/Geode>
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#include <osg/Notify>
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#include <osg/MatrixTransform>
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#include <osg/Texture2D>
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#include <osg/BlendFunc>
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#include <osg/Stencil>
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#include <osg/ColorMask>
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#include <osg/Depth>
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#include <osg/ClipNode>
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#include <osg/AnimationPath>
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#include <osgDB/ReadFile>
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#include <osgUtil/Optimizer>
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#include <osgViewer/Viewer>
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#include <iostream>
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//
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// A simple demo demonstrating planar reflections using multiple renderings
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// of a subgraph, overriding of state attribures and use of the stencil buffer.
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//
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// The multipass system implemented here is a variation if Mark Kilgard's
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// paper "Improving Shadows and Reflections via the Stencil Buffer" which
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// can be found on the developer parts of the NVidia web site.
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//
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// The variations comes from the fact that the mirrors stencil values
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// are done on the first pass, rather than the second as in Mark's paper.
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// The second pass is now Mark's first pass - drawing the unreflected scene,
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// but also unsets the stencil buffer. This variation stops the unreflected
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// world poking through the mirror to be seen in the final rendering and
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// also obscures the world correctly when on the reverse side of the mirror.
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// Although there is still some unresolved issue with the clip plane needing
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// to be flipped when looking at the reverse side of the mirror. Niether
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// of these issues are mentioned in the Mark's paper, but trip us up when
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// we apply them.
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osg::StateSet* createMirrorTexturedState(const std::string& filename)
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{
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osg::StateSet* dstate = new osg::StateSet;
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dstate->setMode(GL_CULL_FACE,osg::StateAttribute::OFF|osg::StateAttribute::PROTECTED);
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// set up the texture.
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osg::Image* image = osgDB::readImageFile(filename.c_str());
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if (image)
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{
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osg::Texture2D* texture = new osg::Texture2D;
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texture->setImage(image);
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dstate->setTextureAttributeAndModes(0,texture,osg::StateAttribute::ON|osg::StateAttribute::PROTECTED);
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}
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return dstate;
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}
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osg::Drawable* createMirrorSurface(float xMin,float xMax,float yMin,float yMax,float z)
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{
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// set up the drawstate.
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// set up the Geometry.
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osg::Geometry* geom = new osg::Geometry;
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osg::Vec3Array* coords = new osg::Vec3Array(4);
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(*coords)[0].set(xMin,yMax,z);
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(*coords)[1].set(xMin,yMin,z);
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(*coords)[2].set(xMax,yMin,z);
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(*coords)[3].set(xMax,yMax,z);
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geom->setVertexArray(coords);
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osg::Vec3Array* norms = new osg::Vec3Array(1);
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(*norms)[0].set(0.0f,0.0f,1.0f);
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geom->setNormalArray(norms);
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geom->setNormalBinding(osg::Geometry::BIND_OVERALL);
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osg::Vec2Array* tcoords = new osg::Vec2Array(4);
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(*tcoords)[0].set(0.0f,1.0f);
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(*tcoords)[1].set(0.0f,0.0f);
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(*tcoords)[2].set(1.0f,0.0f);
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(*tcoords)[3].set(1.0f,1.0f);
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geom->setTexCoordArray(0,tcoords);
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osg::Vec4Array* colours = new osg::Vec4Array(1);
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(*colours)[0].set(1.0f,1.0f,1.0,1.0f);
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geom->setColorArray(colours);
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geom->setColorBinding(osg::Geometry::BIND_OVERALL);
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geom->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::QUADS,0,4));
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return geom;
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}
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osg::Node* createMirroredScene(osg::Node* model)
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{
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// calculate where to place the mirror according to the
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// loaded models bounding sphere.
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const osg::BoundingSphere& bs = model->getBound();
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float width_factor = 1.5;
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float height_factor = 0.3;
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float xMin = bs.center().x()-bs.radius()*width_factor;
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float xMax = bs.center().x()+bs.radius()*width_factor;
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float yMin = bs.center().y()-bs.radius()*width_factor;
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float yMax = bs.center().y()+bs.radius()*width_factor;
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float z = bs.center().z()-bs.radius()*height_factor;
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// create a textured, transparent node at the appropriate place.
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osg::Drawable* mirror = createMirrorSurface(xMin,xMax,yMin,yMax,z);
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osg::MatrixTransform* rootNode = new osg::MatrixTransform;
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rootNode->setMatrix(osg::Matrix::rotate(osg::inDegrees(45.0f),1.0f,0.0f,0.0f));
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// make sure that the global color mask exists.
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osg::ColorMask* rootColorMask = new osg::ColorMask;
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rootColorMask->setMask(true,true,true,true);
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// set up depth to be inherited by the rest of the scene unless
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// overrideen. this is overridden in bin 3.
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osg::Depth* rootDepth = new osg::Depth;
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rootDepth->setFunction(osg::Depth::LESS);
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rootDepth->setRange(0.0,1.0);
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osg::StateSet* rootStateSet = new osg::StateSet();
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rootStateSet->setAttribute(rootColorMask);
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rootStateSet->setAttribute(rootDepth);
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rootNode->setStateSet(rootStateSet);
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// bin1 - set up the stencil values and depth for mirror.
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{
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// set up the stencil ops so that the stencil buffer get set at
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// the mirror plane
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osg::Stencil* stencil = new osg::Stencil;
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stencil->setFunction(osg::Stencil::ALWAYS,1,~0u);
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stencil->setOperation(osg::Stencil::KEEP, osg::Stencil::KEEP, osg::Stencil::REPLACE);
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// switch off the writing to the color bit planes.
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osg::ColorMask* colorMask = new osg::ColorMask;
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colorMask->setMask(false,false,false,false);
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osg::StateSet* statesetBin1 = new osg::StateSet();
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statesetBin1->setRenderBinDetails(1,"RenderBin");
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statesetBin1->setMode(GL_CULL_FACE,osg::StateAttribute::OFF);
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statesetBin1->setAttributeAndModes(stencil,osg::StateAttribute::ON);
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statesetBin1->setAttribute(colorMask);
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// set up the mirror geode.
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osg::Geode* geode = new osg::Geode;
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geode->addDrawable(mirror);
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geode->setStateSet(statesetBin1);
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rootNode->addChild(geode);
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}
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// bin one - draw scene without mirror or reflection, unset
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// stencil values where scene is infront of mirror and hence
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// occludes the mirror.
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{
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osg::Stencil* stencil = new osg::Stencil;
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stencil->setFunction(osg::Stencil::ALWAYS,0,~0u);
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stencil->setOperation(osg::Stencil::KEEP, osg::Stencil::KEEP, osg::Stencil::REPLACE);
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osg::StateSet* statesetBin2 = new osg::StateSet();
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statesetBin2->setRenderBinDetails(2,"RenderBin");
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statesetBin2->setAttributeAndModes(stencil,osg::StateAttribute::ON);
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osg::Group* groupBin2 = new osg::Group();
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groupBin2->setStateSet(statesetBin2);
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groupBin2->addChild(model);
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rootNode->addChild(groupBin2);
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}
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// bin3 - set up the depth to the furthest depth value
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{
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// set up the stencil ops so that only operator on this mirrors stencil value.
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osg::Stencil* stencil = new osg::Stencil;
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stencil->setFunction(osg::Stencil::EQUAL,1,~0u);
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stencil->setOperation(osg::Stencil::KEEP, osg::Stencil::KEEP, osg::Stencil::KEEP);
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// switch off the writing to the color bit planes.
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osg::ColorMask* colorMask = new osg::ColorMask;
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colorMask->setMask(false,false,false,false);
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// set up depth so all writing to depth goes to maximum depth.
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osg::Depth* depth = new osg::Depth;
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depth->setFunction(osg::Depth::ALWAYS);
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depth->setRange(1.0,1.0);
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osg::StateSet* statesetBin3 = new osg::StateSet();
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statesetBin3->setRenderBinDetails(3,"RenderBin");
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statesetBin3->setMode(GL_CULL_FACE,osg::StateAttribute::OFF);
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statesetBin3->setAttributeAndModes(stencil,osg::StateAttribute::ON);
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statesetBin3->setAttribute(colorMask);
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statesetBin3->setAttribute(depth);
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// set up the mirror geode.
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osg::Geode* geode = new osg::Geode;
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geode->addDrawable(mirror);
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geode->setStateSet(statesetBin3);
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rootNode->addChild(geode);
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}
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// bin4 - draw the reflection.
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{
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// now create the 'reflection' of the loaded model by applying
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// create a Transform which flips the loaded model about the z axis
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// relative to the mirror node, the loadedModel is added to the
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// Transform so now appears twice in the scene, but is shared so there
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// is negligable memory overhead. Also use an osg::StateSet
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// attached to the Transform to override the face culling on the subgraph
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// to prevert an 'inside' out view of the reflected model.
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// set up the stencil ops so that only operator on this mirrors stencil value.
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// this clip plane removes any of the scene which when mirror would
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// poke through the mirror. However, this clip plane should really
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// flip sides once the eye point goes to the back of the mirror...
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osg::ClipPlane* clipplane = new osg::ClipPlane;
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clipplane->setClipPlane(0.0,0.0,-1.0,z);
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clipplane->setClipPlaneNum(0);
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osg::ClipNode* clipNode = new osg::ClipNode;
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clipNode->addClipPlane(clipplane);
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osg::StateSet* dstate = clipNode->getOrCreateStateSet();
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dstate->setRenderBinDetails(4,"RenderBin");
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dstate->setMode(GL_CULL_FACE,osg::StateAttribute::OVERRIDE|osg::StateAttribute::OFF);
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osg::Stencil* stencil = new osg::Stencil;
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stencil->setFunction(osg::Stencil::EQUAL,1,~0u);
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stencil->setOperation(osg::Stencil::KEEP, osg::Stencil::KEEP, osg::Stencil::KEEP);
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dstate->setAttributeAndModes(stencil,osg::StateAttribute::ON);
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osg::MatrixTransform* reverseMatrix = new osg::MatrixTransform;
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reverseMatrix->setStateSet(dstate);
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reverseMatrix->preMult(osg::Matrix::translate(0.0f,0.0f,-z)*
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osg::Matrix::scale(1.0f,1.0f,-1.0f)*
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osg::Matrix::translate(0.0f,0.0f,z));
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reverseMatrix->addChild(model);
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clipNode->addChild(reverseMatrix);
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rootNode->addChild(clipNode);
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}
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// bin5 - draw the textured mirror and blend it with the reflection.
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{
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// set up depth so all writing to depth goes to maximum depth.
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osg::Depth* depth = new osg::Depth;
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depth->setFunction(osg::Depth::ALWAYS);
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osg::Stencil* stencil = new osg::Stencil;
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stencil->setFunction(osg::Stencil::EQUAL,1,~0u);
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stencil->setOperation(osg::Stencil::KEEP, osg::Stencil::KEEP, osg::Stencil::ZERO);
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// set up additive blending.
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osg::BlendFunc* trans = new osg::BlendFunc;
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trans->setFunction(osg::BlendFunc::ONE,osg::BlendFunc::ONE);
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osg::StateSet* statesetBin5 = createMirrorTexturedState("Images/tank.rgb");
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statesetBin5->setRenderBinDetails(5,"RenderBin");
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statesetBin5->setMode(GL_CULL_FACE,osg::StateAttribute::OFF);
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statesetBin5->setAttributeAndModes(stencil,osg::StateAttribute::ON);
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statesetBin5->setAttributeAndModes(trans,osg::StateAttribute::ON);
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statesetBin5->setAttribute(depth);
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// set up the mirror geode.
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osg::Geode* geode = new osg::Geode;
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geode->addDrawable(mirror);
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geode->setStateSet(statesetBin5);
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rootNode->addChild(geode);
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}
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return rootNode;
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}
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/////////////////////////////////////////////////////////////////////////////////////////////////////////
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//
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// create the viewer
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// load a model
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// decoate the model so it renders using a multipass stencil buffer technique for planar reflections.
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// release the viewer
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// run main loop.
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//
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int main( int argc, char **argv )
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{
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// use an ArgumentParser object to manage the program arguments.
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osg::ArgumentParser arguments(&argc,argv);
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// construct the viewer.
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osgViewer::Viewer viewer;
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// read the scene from the list of file specified commandline args.
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osg::ref_ptr<osg::Node> loadedModel = osgDB::readNodeFiles(arguments);
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// if no model has been successfully loaded report failure.
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if (!loadedModel)
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{
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std::cout << arguments.getApplicationName() <<": No data loaded" << std::endl;
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return 1;
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}
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// optimize the scene graph, remove rendundent nodes and state etc.
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osgUtil::Optimizer optimizer;
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optimizer.optimize(loadedModel.get());
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// add a transform with a callback to animate the loaded model.
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osg::ref_ptr<osg::MatrixTransform> loadedModelTransform = new osg::MatrixTransform;
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loadedModelTransform->addChild(loadedModel.get());
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osg::ref_ptr<osg::NodeCallback> nc = new osg::AnimationPathCallback(loadedModelTransform->getBound().center(),osg::Vec3(0.0f,0.0f,1.0f),osg::inDegrees(45.0f));
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loadedModelTransform->setUpdateCallback(nc.get());
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// finally decorate the loaded model so that it has the required multipass/bin scene graph to do the reflection effect.
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osg::ref_ptr<osg::Node> rootNode = createMirroredScene(loadedModelTransform.get());
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// set the scene to render
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viewer.setSceneData(rootNode.get());
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// hint to tell viewer to request stencil buffer when setting up windows
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osg::DisplaySettings::instance()->setMinimumNumStencilBits(8);
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return viewer.run();
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}
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