HUD

1. 显示文本；
2. 显示纹理；

#include <Windows.h>
#include <osg/Node>
#include <osg/Group>
#include <osg/Geode>
#include <osg/Camera>
#include <osg/Texture2D>
#include <osgViewer/Viewer>
#include <osgDB/ReadFile>
#include <osgText/Text>

osg::Camera* createHUDCamera(double left, double right, double bottom, double top)
{
	osg::ref_ptr<osg::Camera> camera = new osg::Camera();

	camera->setProjectionMatrix(osg::Matrix::ortho2D(left, right, bottom, top));
	
	camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
	camera->setViewMatrix(osg::Matrix::identity());

	camera->setClearMask(GL_DEPTH_BUFFER_BIT);
	camera->setRenderOrder(osg::Camera::POST_RENDER);
	
	camera->setAllowEventFocus(false);

	camera->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF);

	return camera.release();
}

osgText::Text* createText(const std::string& str)
{
	osg::ref_ptr<osgText::Text> text = new osgText::Text();
	text->getOrCreateStateSet()->setRenderBinDetails(0, "DepthSortedBin");
	text->setPosition(osg::Vec3(10.0, 10.0, 0.0));
	text->setCharacterSize(32);
	text->setText(str);
	return text.release();
}

osg::Geode* createTexture(const std::string& path)
{
	osg::ref_ptr<osg::Geode> geode = new osg::Geode();
	geode->getOrCreateStateSet()->setRenderBinDetails(1, "DepthSortedBin");
	osg::ref_ptr<osg::Geometry> geometry = osg::createTexturedQuadGeometry(osg::Vec3(), osg::Vec3(200.0f, 0.0f, 0.0f), osg::Vec3(0.0f, 200.0f, 0.0f));
	osg::ref_ptr<osg::Texture2D> texture = new osg::Texture2D();
	texture->setImage(osgDB::readImageFile(path));
	geometry->getOrCreateStateSet()->setTextureAttributeAndModes(0, texture);
	geode->addDrawable(geometry);
	return geode.release();
}

int main()
{
	osgViewer::Viewer viewer;

	osg::ref_ptr<osg::Group> group = new osg::Group();
	group->addChild(osgDB::readNodeFile("glider.osg"));

	osg::ref_ptr<osg::Camera> camera = createHUDCamera(0, 800, 0, 600);
	camera->addChild(createText("glider"));
	camera->addChild(createTexture("Images/blueFlowers.png"));
	group->addChild(camera);

	viewer.setSceneData(group);
	viewer.setUpViewInWindow(100, 100, 500, 400);
	return viewer.run();
}