基础图元 Box

创建一个长方体（Box）

效果图：

步骤：

1. 申请一个精度

   osg::ref_ptr<osg::TessellationHints> hints = new osg::TessellationHints;
   
   hints->setDetailRatio(0.5);
   

2. 申请一个Shape（需要赋值精细度）

   osg::ref_ptr<osg::ShapeDrawable> shape = new osg::ShapeDrawable(new osg::Box(osg::Vec3(0.0, 0.0, 0.0), 1.0, 10.0, 10.0), hints.get());
   
   //赋值为灰色，半透明
   shape->setColor(osg::Vec4(0.5, 0.5, 0.5, 0.5));
   

3. 申请一个材质

   osg::ref_ptr<osg::Material> material = new osg::Material;
   
   material->setAmbient(osg::Material::FRONT_AND_BACK, osg::Vec4f(1.0, 1.0, 1.0, 0.5));
   material->setDiffuse(osg::Material::FRONT_AND_BACK, osg::Vec4f(1.0, 1.0, 1.0, 0.5));
   material->setSpecular(osg::Material::FRONT_AND_BACK, osg::Vec4f(1.0, 1.0, 1.0, 0.5));
   material->setShininess(osg::Material::FRONT_AND_BACK, 6.0);
   

4. 申请一个纹理和Image

   osg::ref_ptr<osg::Texture2D> texture2D = new osg::Texture2D;
   osg::ref_ptr<osg::Image> image = new osg::Image;
   
   image = osgDB::readImageFile("Images/whitemetal_diffuse.jpg");
   
   if (image.valid()) {
   	texture2D->setImage(image.get());
   }
   

5. 申请一个Geode作为函数返回值

   osg::ref_ptr<osg::Geode> geode = new osg::Geode;
   
   geode->getOrCreateStateSet()->setAssociatedModes(material.get(), osg::StateAttribute::ON);
   geode->getOrCreateStateSet()->setMode(GL_BLEND, osg::StateAttribute::ON);
   geode->getOrCreateStateSet()->setMode(GL_DEPTH_TEST, osg::StateAttribute::ON);
   geode->getOrCreateStateSet()->setTextureAttributeAndModes(0, texture2D.get(), osg::StateAttribute::ON);
   

6. 在geode中绘制shape

   geode->addDrawable(shape.get());
   

7. 将返回的Geode添加到group中

   group->addChild(CreateBox());
   

8. 完整代码

   #include <osgViewer/Viewer>
   #include <osgDB/ReadFile>
   #include <osgGA/GUIEventAdapter>
   #include <osgViewer/ViewerEventHandlers>
   #include <osg/Geode>
   #include <osg/ShapeDrawable>
   #include <osg/Material>
   #include <osg/StateSet>
   #include <osg/Image>
   #include <osg/Texture2D>
   #include <iostream>
   using namespace std;
   
   osg::ref_ptr<osg::Geode> CreateBox() {
   
   	osg::ref_ptr<osg::Geode> geode = new osg::Geode;
   	osg::ref_ptr<osg::TessellationHints> hints = new osg::TessellationHints;
   	osg::ref_ptr<osg::ShapeDrawable> shape = new osg::ShapeDrawable(new osg::Box(osg::Vec3(0.0, 0.0, 0.0), 1.0, 10.0, 10.0), hints.get());
   	osg::ref_ptr<osg::Material> material = new osg::Material;
   	osg::ref_ptr<osg::Texture2D> texture2D = new osg::Texture2D;
   	osg::ref_ptr<osg::Image> image = new osg::Image;
   
   	hints->setDetailRatio(0.5);
   
   	shape->setColor(osg::Vec4(0.5, 0.5, 0.5, 0.5));
   
   	material->setAmbient(osg::Material::FRONT_AND_BACK, osg::Vec4f(1.0, 1.0, 1.0, 0.5));
   	material->setDiffuse(osg::Material::FRONT_AND_BACK, osg::Vec4f(1.0, 1.0, 1.0, 0.5));
   	material->setSpecular(osg::Material::FRONT_AND_BACK, osg::Vec4f(1.0, 1.0, 1.0, 0.5));
   	material->setShininess(osg::Material::FRONT_AND_BACK, 6.0);
   
   	image = osgDB::readImageFile("Images/whitemetal_diffuse.jpg");
   	if (image.valid()) {
   		texture2D->setImage(image.get());
   	}
   
   	//set state
   	geode->getOrCreateStateSet()->setAssociatedModes(material.get(), osg::StateAttribute::ON);
   	geode->getOrCreateStateSet()->setMode(GL_BLEND, osg::StateAttribute::ON);
   	geode->getOrCreateStateSet()->setMode(GL_DEPTH_TEST, osg::StateAttribute::ON);
   	geode->getOrCreateStateSet()->setTextureAttributeAndModes(0, texture2D.get(), osg::StateAttribute::ON);
   	geode->addDrawable(shape.get());
   
   	return geode;
   }
   
   int main() {
   
   	osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer;
   	osg::ref_ptr<osg::Group> group = new osg::Group;
   	
   	group->addChild(CreateBox());
   	viewer->setSceneData(group.get());
   
   	return viewer->run();
   }