osg::ref_ptr＜osg::CullFace＞ cf = new osg::CullFace；提高帧率

前言

当我使用osg绘制场景的时候，绘制大量相同图元的时候时候，如果不设置背面剔除的话，当顶点数量达到上百万个很多显卡都吃不消，帧率会掉的很快，我的显卡是NVIDIA GeForce GTX 1660 Ti

运行下面一段代码

//Geometry->Drawable->Node->Object->Referenced
//AlphaFunc->StateAttribute->Object->Referenced
//StateAttributeCallback->Callback->Object->Referenced
//ClearNode->Group->Node->Object->Referenced
//CoordinateSystemNode->Group->Node->Object->Referenced
//Billboard->Geode->Group->Node->Object->Referenced
//Image->BufferData->Object->Referenced
//Texture1D/Texture2D/Texture2DArray/Texture3D->Texture->TextureAttribute->StateAttribute->Object->Referenced

//Group->Node->Object->Referenced
//Geode->Group->Node->Object->Referenced
//Geometry->Drawable->Node->Object->Referenced
//AlphaFunc->StateAttribute->Object->Referenced
//StateAttributeCallback->Callback->Object->Referenced
//ClearNode->Group->Node->Object->Referenced
//CoordinateSystemNode->Group->Node->Object->Referenced
//Billboard->Geode->Group->Node->Object->Referenced
//Image->BufferData->Object->Referenced
//Texture1D/Texture2D/Texture2DArray/Texture3D->Texture->TextureAttribute->StateAttribute->Object->Referenced
//DrawArrays->PrimitiveSet->BufferData->Object->Object->Referenced
//MatrixTransform->Transform->Group->Node->Object->Referenced
//StateSet->Object

//StateAttribute->Object
//hadeModel->StateAttribute->Object
//CullFace->StateAttribute->Object
//PolygonMode->StateAttribute->Object

#include "osg/Group"
#include "osg/Geode"
#include "osg/Geometry"
#include "osg/Point"
#include "osg/Drawable"
#include "osg/StateAttribute"
#include "osg/StateSet"
#include "osg/Material"
#include "osg/MatrixTransform"
#include "osg/Matrix"
#include "osg/LightSource"
#include "osg/Light"
#include "osgDB/ReadFile"
#include "osgDB/WriteFile"
#include "osg/Notify"
#include "osg/CullFace"
#include "osgViewer/Viewer"
#include "osgUtil/Optimizer"

using namespace osg;
using namespace std;

osg::ref_ptr<osg::Geode> createLightPoint()
{
  osg::ref_ptr<osg::Geometry> geom = new osg::Geometry();

  // Don't throw away single-vertex primitives.
  //边界盒
  osg::BoundingBox bBox(-.1f, -.1f, -.1f, .1f, .1f, .1f);
  geom->setInitialBound(bBox);

  osg::ref_ptr<osg::Vec3Array> v = new osg::Vec3Array();
  geom->setVertexArray(v.get());
  v->push_back(osg::Vec3f(0.f, 0.f, 0.f));

  osg::ref_ptr<osg::Vec4Array> c = new osg::Vec4Array();
  geom->setColorArray(c.get());
  geom->setColorBinding(osg::Geometry::BIND_OVERALL);  //BIND_OVERALL:这个光源都是颜色绑定方式对应唯一的颜色：红色
  c->push_back(osg::Vec4f(1.f, 0.f, 0.f, 1.f));

  geom->addPrimitiveSet(new osg::DrawArrays(GL_POINTS, 0, 1));  //基本图元是绘制点

  //Geode是叶子节点，把Geometry加入到叶子节点中
  osg::ref_ptr<osg::Geode> geode = new osg::Geode;
  geode->addDrawable(geom.get());

  //设置状态属性
  osg::ref_ptr<StateSet> state = geode->getOrCreateStateSet();
  state->setMode(GL_LIGHTING, osg::StateAttribute::OFF | osg::StateAttribute::PROTECTED);
  osg::ref_ptr<osg::Point> pt = new osg::Point();
  pt->setSize(10.f);
  state->setAttribute(pt.get());

  return (geode.release());
  //return (geode);
}

osg::ref_ptr<osg::Drawable> createPlane()
{
  osg::ref_ptr<osg::Geometry> geom = new osg::Geometry();

  //顶点
  osg::ref_ptr<osg::Vec3Array> v = new osg::Vec3Array();
  geom->setVertexArray(v.get());
  int x, y;
  for (y = -10; y <= 10; y++)
  {
    for (x = -10; x <= 10; x++)
    {
      v->push_back(osg::Vec3((float)x * .5f, (float)y * .5f, 0.f));
    }
  }

  //法线
  osg::ref_ptr<osg::Vec3Array> n = new osg::Vec3Array();
  geom->setNormalArray(n.get());
  geom->setNormalBinding(osg::Geometry::BIND_OVERALL);
  n->push_back(osg::Vec3(0.f, 0.f, 1.f));

  //颜色
  osg::ref_ptr<osg::Vec4Array> c = new osg::Vec4Array();
  geom->setColorArray(c.get());
  geom->setColorBinding(osg::Geometry::BIND_OVERALL);
  c->push_back(osg::Vec4(1.f, 1.f, 1.f, 1.f));

  const int len(21);
  int idx(0);
  int numStrips(len - 1);
  while (numStrips--)
  {
    GLushort indices[len + len];
    int vert(0);
    while (vert < len)
    {
      indices[2 * vert + 0] = idx + len;
      indices[2 * vert + 1] = idx;
      vert++;
      idx++;
    }
    //geom->addPrimitiveSet(new osg::DrawElementsUShort(osg::PrimitiveSet::QUADS, len + len, indices));
    geom->addPrimitiveSet(new osg::DrawElementsUShort(osg::PrimitiveSet::QUAD_STRIP, len + len, indices));
  }

  return (geom.release());
}


//1.指定几何体法线
//2.允许光照并设置光照状态
//3.指定光源属性并关联到场景图形
//4.指定物体表面材质属性
//5.只有光源并没有阴影，阴影需要sogShadow来创建
osg::ref_ptr<osg::Node> createSceneGraph()
{
  // Create the root node and set state for the entire subgraph.
  osg::ref_ptr<osg::Group> group = new osg::Group();
  osg::ref_ptr<osg::Node> root = new osg::Node();
  {
    osg::ref_ptr<osg::StateSet> state = group->getOrCreateStateSet();
    state->setMode(GL_LIGHTING, osg::StateAttribute::ON);
    state->setMode(GL_LIGHT0, osg::StateAttribute::ON);
    state->setMode(GL_LIGHT1, osg::StateAttribute::ON);
  }
  // Represent the two light sources with a shared point.
  // Each light's position is 0,0,0 in object coordinates. The
  //   two parent MatrixTransforms translate the lights, and the
  //   shared point, to their actual positions.
  //osg::ref_ptr<osg::Geode> lightPoint = new osg::Geode;
  osg::ref_ptr<osg::Geode> lightPoint = createLightPoint();
  {
    
    
    osg::ref_ptr<osg::MatrixTransform> mt = new osg::MatrixTransform;
    //osg::Matrix 没有继承Referenced 所以不能用智能指针
    osg::Matrix m;
    osg::ref_ptr<RefMatrix> refM = new osg::RefMatrix;

    refM->makeTranslate(osg::Vec3(-3.f, 2.f, 5.f));
    mt->setMatrix(*refM);

    // Create a mostly red light
    osg::ref_ptr<osg::Light> light = new osg::Light;
    light->setLightNum(0);
    light->setPosition(osg::Vec4(0.f, 0.f, 0.f, 1.f));
    light->setDiffuse(osg::Vec4(1.f, .5f, .5f, 1.f));
    light->setSpecular(osg::Vec4(1.f, .8f, .8f, 1.f));

    //设置光源：第一个光源
    osg::ref_ptr<osg::LightSource> ls = new osg::LightSource;
    group->addChild(mt.get());
    //mt->setMatrix(*m);
    mt->addChild(ls.get());
    ls->setLight(light.get());
    ls->addChild(lightPoint.get());
  }

  {
    osg::ref_ptr<osg::MatrixTransform> mt = new osg::MatrixTransform;
    osg::ref_ptr<osg::RefMatrix> refM = new osg::RefMatrix;
    refM->makeTranslate(osg::Vec3(3.f, -2.f, 3.f));
    mt->setMatrix(*refM);

    // Create a mostly blue light
    osg::ref_ptr<osg::Light> light = new osg::Light;
    light->setLightNum(1);
    light->setPosition(osg::Vec4(0.f, 0.f, 0.f, 1.f));
    light->setDiffuse(osg::Vec4(.5f, .5f, 1.f, 1.f));
    light->setSpecular(osg::Vec4(.8f, .8f, 1.f, 1.f));

    //设置光源:第二个光源
    osg::ref_ptr<osg::LightSource> ls = new osg::LightSource;
    group->addChild(mt.get());
    mt->addChild(ls.get());
    ls->setLight(light.get());
    ls->addChild(lightPoint.get());
  }

  // Create a single instance of the lozenge geometry (read from disk).
  // Multiply parent it to six MatrixTransform nodes, each with their
  //   own StateSet to change the material properties of the lozenge.
  osg::ref_ptr<osg::Node> lozenge = osgDB::readNodeFile("lozenge.osg");
  if (!lozenge.valid())
  {
    osg::notify(osg::FATAL) << "Unload to load date file. Exiting." << std::endl;
    return nullptr;
  }

  {
    osg::ref_ptr<osg::MatrixTransform> mt = new osg::MatrixTransform;
    //osg::Matrix 没有继承Referenced 所以不能用智能指针
    osg::Matrix m;
    osg::ref_ptr<osg::RefMatrix> refM = new osg::RefMatrix;
    refM->makeTranslate(osg::Vec3(-1.f, -1.f, 1.f));
    mt->setMatrix(*refM);

    //设置属性
    osg::ref_ptr<osg::StateSet> state = new osg::StateSet;
    state = mt->getOrCreateStateSet();
    //背面剔除
    osg::ref_ptr<osg::CullFace> cf = new osg::CullFace;
    state->setAttributeAndModes(cf.get());
    osg::ref_ptr<osg::Material> mat = new osg::Material;
    mat->setDiffuse(osg::Material::FRONT, osg::Vec4(0.f, 0.f, 0.f, 1.f));
    mat->setSpecular(osg::Material::FRONT, osg::Vec4(1.f, 1.f, 1.f, 1.f));
    mat->setShininess(osg::Material::FRONT, 128.f);
    state->setAttribute(mat.get());

    mt->addChild(lozenge.get());
    group->addChild(mt.get());
  }
  {
    osg::ref_ptr<osg::MatrixTransform> mt = new osg::MatrixTransform;
    //osg::Matrix 没有继承Referenced 所以不能用智能指针
    osg::Matrix m;
    osg::ref_ptr<osg::RefMatrix> refM = new osg::RefMatrix;
    refM->makeTranslate(osg::Vec3(1.f, -1.f, 1.f));
    mt->setMatrix(*refM);

    //设置属性
    osg::ref_ptr<StateSet> state = mt->getOrCreateStateSet();
    //背面剔除
    osg::ref_ptr<osg::CullFace> cf = new osg::CullFace;
    state->setAttributeAndModes(cf.get());
    osg::ref_ptr<osg::Material> mat = new osg::Material;
    // Just use the object's primary color for ambient and
     //   diffuse (uses the OpenGL color material feature).
    mat->setColorMode(osg::Material::AMBIENT_AND_DIFFUSE);
    state->setAttribute(mat.get());
    mat->setDiffuse(osg::Material::FRONT, osg::Vec4(.4f, .3f, 0.f, 1.f));
    mat->setSpecular(osg::Material::FRONT, osg::Vec4(.8f, .8f, .1f, 1.f));
    mat->setShininess(osg::Material::FRONT, 20.f);
    state->setAttribute(mat.get());

    mt->addChild(lozenge.get());
    group->addChild(mt.get());
  }

  {
    osg::ref_ptr<MatrixTransform> mt = new osg::MatrixTransform;
    //osg::Matrix 没有继承Referenced 所以不能用智能指针
    osg::Matrix m;
    osg::ref_ptr<osg::RefMatrix> refM = new osg::RefMatrix;
    refM->makeTranslate(osg::Vec3(-1.f, 0.f, 1.f));
    mt->setMatrix(*refM);

    osg::ref_ptr<osg::StateSet> state = mt->getOrCreateStateSet();
    //背面剔除
    osg::ref_ptr<osg::CullFace> cf = new osg::CullFace;
    state->setAttributeAndModes(cf.get());
    osg::ref_ptr<osg::Material> mat = new osg::Material;
    mat->setDiffuse(osg::Material::FRONT, osg::Vec4(.4f, .3f, 0.f, 1.f));
    mat->setSpecular(osg::Material::FRONT, osg::Vec4(.8f, .8f, 1.f, 1.f));
    mat->setShininess(osg::Material::FRONT, 20.f);
    state->setAttribute(mat.get());

    mt->addChild(lozenge.get());
    group->addChild(mt.get());
  }

  {
    osg::ref_ptr<osg::MatrixTransform> mt = new osg::MatrixTransform;
    //osg::Matrix 没有继承Referenced 所以不能用智能指针
    osg::Matrix m;
    osg::ref_ptr<osg::RefMatrix> refM = new osg::RefMatrix;
    refM->makeTranslate(osg::Vec3(1.f, 0.f, 1.f));
    mt->setMatrix(*refM);

    //设置属性
    osg::ref_ptr<osg::StateSet> state = mt->getOrCreateStateSet();
    //背面剔除
    osg::ref_ptr<osg::CullFace> cf = new osg::CullFace;
    state->setAttributeAndModes(cf.get());
    osg::ref_ptr<osg::Material> mat = new osg::Material;
    mat->setDiffuse(osg::Material::FRONT, osg::Vec4(.1f, .2f, .5f, 1.f));
    mat->setSpecular(osg::Material::FRONT, osg::Vec4(.9f, .9f, 1.f, 1.f));
    mat->setShininess(osg::Material::FRONT, 10.f);
    state->setAttribute(mat.get());

    mt->addChild(lozenge.get());
    group->addChild(mt.get());
  }

  {
    osg::ref_ptr<osg::MatrixTransform> mt = new osg::MatrixTransform;
    //osg::Matrix 没有继承Referenced 所以不能用智能指针
    osg::Matrix m;
    osg::ref_ptr<osg::RefMatrix> refM = new osg::RefMatrix;
    refM->makeTranslate(osg::Vec3(-1.f, 1.f, 1.f));
    mt->setMatrix(*refM);

    osg::ref_ptr<osg::StateSet> state = mt->getOrCreateStateSet();
    //背面剔除
    osg::ref_ptr<osg::CullFace> cf = new osg::CullFace;
    state->setAttributeAndModes(cf.get());
    osg::ref_ptr<osg::Material> mat = new osg::Material;
    mat->setDiffuse(osg::Material::FRONT, osg::Vec4(.2f, .9f, .9f, 1.f));
    mat->setSpecular(osg::Material::FRONT, osg::Vec4(1.f, 1.f, 1.f, 1.f));
    mat->setShininess(osg::Material::FRONT, 96.f);
    state->setAttribute(mat.get());

    mt->addChild(lozenge.get());
    group->addChild(mt.get());
  }

  {
    osg::ref_ptr<osg::MatrixTransform> mt = new osg::MatrixTransform;
    osg::ref_ptr<osg::RefMatrix> refM = new osg::RefMatrix;
    refM->makeTranslate(osg::Vec3(1.f, 1.f, 1.f));
    mt->setMatrix(*refM);

    osg::ref_ptr<osg::StateSet> state = mt->getOrCreateStateSet();
    //背面剔除
    osg::ref_ptr<osg::CullFace> cf = new osg::CullFace;
    state->setAttributeAndModes(cf.get());
    osg::ref_ptr<osg::Material> mat = new osg::Material;
    mat->setDiffuse(osg::Material::FRONT, osg::Vec4(1.f, 1.f, 1.f, 1.f));
    mat->setSpecular(osg::Material::FRONT, osg::Vec4(0.f, 0.f, 0.f, 1.f));
    mat->setShininess(Material::FRONT, 0.f);
    state->setAttribute(mat.get());

    mt->addChild(lozenge.get());
    group->addChild(mt.get());

  }


  osg::ref_ptr<osg::Geode> planeGeode = new osg::Geode;
  planeGeode->addDrawable(createPlane());
  {
    osg::ref_ptr<osg::StateSet> state = new osg::StateSet;
    state = planeGeode->getOrCreateStateSet();
    //背面剔除
    osg::ref_ptr<osg::CullFace> cf = new osg::CullFace;
    state->setAttributeAndModes(cf.get());
    osg::ref_ptr<osg::Material> mat = new osg::Material;
    mat->setDiffuse(osg::Material::FRONT, osg::Vec4(.6f, .5f, .2f, 1.f));
    mat->setSpecular(osg::Material::FRONT, osg::Vec4(.4f, .4f, .4f, 1.f));
    mat->setShininess(osg::Material::FRONT, 128.f);
    state->setAttribute(mat.get());

    /*osg::ref_ptr<osg::CullFace> cf = new osg::CullFace;
    state->setAttributeAndModes(cf.get());*/
  }

  group->addChild(planeGeode.get());

  return group.release();
}

int main(int argc, char** argv)
{
  osg::ref_ptr<osg::Node> root = createSceneGraph();
  if (!root.valid())
  {
    osg::notify(osg::FATAL) << "Failed in createSceneGraph()." << std::endl;
    return (1);
  }

  

  //每次执行writeNodeFile都会往lozenge.osg文件中写入顶点，默认是追加写入，所以lozenge.osg文件会越来越大，直到显卡崩溃
  std::string out("lozenge.osg");
  if (!(osgDB::writeNodeFile(*(root.get()), out)))
  {
    osg::notify(osg::FATAL) << "Failed in osgDB::writeNodeFile()." << std::endl;
    return (1);
  }

  osg::notify(osg::ALWAYS) << "Successfully wrote \"" << out << "\". Execute \"osgviewer " << out << "\" to view." << endl;

  osgViewer::Viewer viewer;
  auto node = osgDB::readNodeFile("lozenge.osg");
  osgUtil::Optimizer opt;
  opt.optimize(node);
  //node->setUseDisplayList(false);
  auto geom = node->asGeometry();
  //geom->setUseVertexArrayObject(true);



  viewer.setSceneData(node);

  return viewer.run();
}

使用window PowerShell 运行osgviewer.exe lozenge.osg

当达到400多万个顶点，帧率只有不到30帧，这还是使用了osg::CullFace,如果不用背面剔除，帧率变下降到原来的五分之一左右，大概6帧的样子

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