可把VSG 物体绘制分为5个步骤：

（1）状态设置，由vrState 类完成。主要代码为：

vrState *pState=new vrState;

vrAlphaBlend::Element alphaBlendElement;

alphaBlendElement.m_enable=true;

pState->setElement(vrAlphaBlend::Element::Id,&alphaBlendElement);

（2）物体的绘制，由vrGeometry 类完成。主要代码为：

vrGeometry *pRGrom=new vrGeometry;

vuVec4<float> *color=vuAllocArray<vuVec4<float> >::malloc(1);

color[0].set(1.0f,1.0f,0.0f,1.0f);

vuVec3<float> *vertex=vuAllocArray<vuVec3<float> >::malloc(4);

vertex[0].set(-0.5f,-0.5f,0.0f);

vertex[1].set(0.5f,-0.5f,0.0f);

vertex[2].set(-0.5f,-0.3f,0.0f);

vertex[3].set(0.5f,-0.3f,0.0f);

pRGrom->setPrimitive(vrGeometry::PRIMITIVE_LINE);

pRGrom->setNumPrimitives(2);

pRGrom->setColors(color,vrGeometry::BINDING_OVERALL);(www.daowen.com)

pRGrom->setVertices(vertex);

（3）用vsGeometry 包装vrGeometry。主要代码为：

vsGeometry *pSGeom=new vsGeometry;

pSGeom->setGeometry(pRGrom);

pSGeom->setState(pState);

（4）将vsGeometry 作为子物体加到vpTransform 中。主要代码为：

vpTransform *pTrans =new vpTransform();

pTrans->setTranslate(2360.000000,2490.000000,3.000000);

pTrans->setRotate(0.000000,0.000000,0.000000);

pTrans->setScale(10.000000,10.000000,10.000000);

pTrans->insert_child(pSGeom,pTrans->end_child());

pTrans->ref();

（5）vpTransform 作为孩子添加到场景中。主要代码为：

vpScene* Scene=(vpScene*)vpScene::find("myScene");

Scene->addChild(pTrans);

下一节将会详细展示VSG 绘图的完整过程。