#include <osgViewer/ViewerEventHandlers>
#include <osgViewer/Viewer>
#include <osgDB/ReadFile>

//render to texture,纹理烘焙
static osg::Texture* createRttTexture(int texWidth, int texHeight)
{
	osg::ref_ptr<osg::Texture2D> texture = new osg::Texture2D;
	texture->setInternalFormat(GL_RGBA);
	texture->setFilter(osg::Texture::MIN_FILTER, osg::Texture::LINEAR);
	texture->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
	texture->setTextureSize(texWidth, texHeight);

	return texture.release();
}

static osg::Camera* createRttCamera(int texWidth, int texHeight, const osg::BoundingSphere& bs)
{
	osg::ref_ptr<osg::Camera> rttCamera = new osg::Camera;
	rttCamera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	rttCamera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
	rttCamera->setViewport(0, 0, texWidth, texHeight);
	rttCamera->setRenderOrder(osg::Camera::PRE_RENDER);
	rttCamera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);

	double viewDistance = 2.0 * bs.radius();
	double znear = viewDistance - bs.radius();
	double zfar = viewDistance + bs.radius();
	float top = 0.6 * znear;
	float right = 0.8 * znear;
	rttCamera->setProjectionMatrixAsFrustum(-right, right, -top, top, znear, zfar);

	osg::Vec3d upDirection(0.0, 0.0, 1.0);
	osg::Vec3d viewDirection(0.0, -1.0, 0.0);
	osg::Vec3d center = bs.center();
	osg::Vec3d eyePoint = center + viewDirection * viewDistance;
	rttCamera->setViewMatrixAsLookAt(eyePoint, center, upDirection);

	return rttCamera.release();
}
osg::ref_ptr<osg::Group> renderToTexture()
{
	osg::Node *model = osgDB::readNodeFile("D:/osgData/axes.osgt");
	model->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF);
	osg::ref_ptr<osg::Geode> quad = new osg::Geode;
	quad->addDrawable(osg::createTexturedQuadGeometry(osg::Vec3(0.0, 0.0, 0.0), osg::Vec3(1.0, 0.0, 0.0), osg::Vec3(0.0, 0.0, 1.0)));

	int texWidth = 512, texHeight = 512;
	osg::Camera *rttCamera = createRttCamera(texWidth, texHeight, model->getBound());
	osg::Texture* rttTexture = createRttTexture(texWidth, texHeight);
	rttCamera->addChild(model);
	rttCamera->attach(osg::Camera::COLOR_BUFFER, rttTexture);
	quad->getOrCreateStateSet()->setTextureAttributeAndModes(0, rttTexture);

	osg::ref_ptr<osg::Group> root = new osg::Group;
	root->addChild(quad.get());
	root->addChild(rttCamera);
	return root.release();
}

int main(int argc, char *argv[])
{
	osg::ref_ptr<osgViewer::Viewer> rpViewer = new osgViewer::Viewer;
	rpViewer->setSceneData(renderToTexture());
	rpViewer->setUpViewInWindow(35, 35, 1084, 800);
	return rpViewer->run();
}