#include "osg/Group"
#include "osgText/Text"
#include "osg/Geode"
#include "osg/Geometry"
#include "osgText/Font"
#include "osgDB/WriteFile"
#include "osgDB/ReadFile"
#include "osg/Node"
#include "osg/ref_ptr"
#include "osgViewer/View"
#include "osgViewer/Viewer"
#include "osg/Matrix"
#include "osg/MatrixTransform"
#include "osg/ShadeModel"

//创建背板
osg::ref_ptr<osg::Drawable> createBase()
{
  osg::ref_ptr<osg::Group> group = new osg::Group;
  osg::ref_ptr<osg::Geometry> geom = new osg::Geometry;

  osg::Matrix m;
  osg::ref_ptr<osg::MatrixTransform> mt = new osg::MatrixTransform();
  m.makeRotate(45.f, osg::Vec3(0.f, 1.f, 0.f));
  mt->setMatrix(m);
  group->addChild(mt.get());
  mt->addChild(geom.get());

  //设置状态属性
  osg::ref_ptr<osg::StateSet> state = mt->getOrCreateStateSet();
  osg::ref_ptr<osg::ShadeModel> sm = new osg::ShadeModel;   //默认背面剔除
  sm->setMode(osg::ShadeModel::FLAT);
  


  osg::ref_ptr<osg::Vec3Array> v = new osg::Vec3Array;
  geom->setVertexArray(v.get());
  v->push_back(osg::Vec3(-1.f, 0.f, -1.f));
  v->push_back(osg::Vec3(1.f, 0.f, -1.f));
  v->push_back(osg::Vec3(1.f, 0.f, 1.f));
  v->push_back(osg::Vec3(-1.f, 0.f, 1.f));

  osg::ref_ptr<osg::Vec4Array> c = new osg::Vec4Array;
  geom->setColorArray(c.get());
  /*setColorBinding()和setNormalBinding() - 这些方法用于设置Geometry 类
    中颜色和法线数据的绑定方式。其输入参数为Geometry 类的枚举量。
    清单2 - 1 中，颜色绑定方式为osg::Geometry::BIND_PER_VERTEX，即
    每种颜色对应一个顶点。而法线的绑定方式为
    osg::Geometry::BIND_OVERALL，即整个Geometry 几何体对应唯一的
    一个法线数据。*/
  geom->setColorBinding(osg::Geometry::BIND_PER_VERTEX);
  c->push_back(osg::Vec4(1.f, 1.f, 0.f, 1.f));
  c->push_back(osg::Vec4(0.f, 1.f, 0.f, 1.f));
  c->push_back(osg::Vec4(0.f, 0.f, 1.f, 1.f));
  c->push_back(osg::Vec4(1.f, 1.f, 1.f, 1.f));

  //法线
  osg::ref_ptr<osg::Vec3Array> n = new osg::Vec3Array;
  geom->setNormalArray(n.get());
  /*而法线的绑定方式为
    osg::Geometry::BIND_OVERALL，即整个Geometry 几何体对应唯一的
    一个法线数据。*/
  geom->setNormalBinding(osg::Geometry::BIND_OVERALL);
  n->push_back(osg::Vec3(0.f, 1.f, 0.f));

  geom->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::TRIANGLE_FAN, 0, 4));
  
  return (geom.release());

}

osg::ref_ptr<osg::Node> createSceneGraph()
{
  // Create the root (and only) node.
  osg::ref_ptr<osg::Geode> geode = new osg::Geode;
  geode->addDrawable(createBase());

  //字体
  osg::ref_ptr<osgText::Font> font = new osgText::Font;
  font = osgText::readFontFile("fonts/arial.ttf");


  

  osg::Vec4 white(osg::Vec4(1.f, 1.f, 1.f, 1.f));
  {
    //Text.osg文件中有个默认参数：autoRotateToScreen，始终保持字体面向屏幕
    osg::ref_ptr<osgText::Text> text = new osgText::Text;
    text->setFont(font.get());
    text->setColor(osg::Vec4(0.f, 1.f, 1.f, 1.f));  //青色
    text->setCharacterSize(.15f);
    text->setPosition(osg::Vec3(1.f, 0.f, 1.f));
    /*如果要创建一个一直朝向视口的广告牌形式的文
      字，可以使用Text::SCREEN。*/
    text->setAxisAlignment(osgText::Text::XY_PLANE);//因为没有设置SCREEN，所以在Text.osg文件中没有autoRotateToScreen TRUE 属性
    text->setAlignment(osgText::Text::LEFT_TOP);  //左上基准点开始的字体
    text->setText("right_right");
    geode->addDrawable(text.get());

    text->setDataVariance(osg::Object::DYNAMIC);
  }

  {
    osg::ref_ptr<osgText::Text> text = new osgText::Text;
    text->setFont(font.get());
    text->setColor(osg::Vec4(1.f, 0.f, 0.f, 1.f));
    text->setCharacterSize(.15f);
    text->setPosition(osg::Vec3(-1.f, 0.f, 0.f));
    text->setAxisAlignment(osgText::Text::SCREEN); //因为没有设置SCREEN，所以在Text.osg文件中有autoRotateToScreen TRUE 属性
    text->setText("right_right");
    text->setText("Top_left");
    geode->addDrawable(text.get());
  }

  {
    osg::ref_ptr<osgText::Text> text = new osgText::Text;
    text->setFont(font.get());
    text->setColor(osg::Vec4(0.f, 1.f, 0.f, 1.f));
    text->setCharacterSize(.15f);
    text->setPosition(osg::Vec3(-1.f, -1.f, 0.f));
    text->setAxisAlignment(osgText::Text::SCREEN);
    text->setText("Bottom_left");
    geode->addDrawable(text.get());
  }

  {
    osg::ref_ptr<osgText::Text> text = new osgText::Text;
    text->setFont(font.get());
    text->setColor(osg::Vec4(0.f, 0.f, 1.f, 1.f));
    text->setCharacterSize(.15f);
    text->setPosition(osg::Vec3(1.f, -1.f, 0.f));
    text->setAxisAlignment(osgText::Text::SCREEN); //因为没有设置SCREEN，所以在Text.osg文件中有autoRotateToScreen TRUE 属性
    text->setText("Bottom_right");
    geode->addDrawable(text.get());
  }

  {
    osg::ref_ptr<osgText::Text> text = new osgText::Text;
    text->setFont(font.get());
    /*用户程序通常需要改变字体纹理贴图的图形分辨率，以避免文字出现模糊。
      缺省情况下，osgText 为每个图形分配了32×32 个像素元。要改变这个数值的话，
      可以使用Text::setFontResolution()方法。下面的代码增加了字体的分辨率，osgText
      将因此为每个图形分配128×128 个像素元。*/
    text->setFontResolution(128, 128);
    text->setColor(osg::Vec4(1.f, 0.f, 1.f, 1.f));
    text->setCharacterSize(.15f);
    text->setPosition(osg::Vec3(0.f, 0.f, 0.f));
    //text->setAxisAlignment(osgText::Text::SCREEN);
    text->setAxisAlignment(osgText::Text::XZ_PLANE);  //沿xz平面,倒下
    /*文字相对于自身坐标位置*/
    text->setAlignment(osgText::Text::CENTER_TOP);
    text->setText("Hello osg world");
    geode->addDrawable(text.get());
  }

  return geode.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;
  }

  // 已经有Text.osg文件，暂时不用写此文件
  std::string out("Text.osg");
  if (!(osgDB::writeNodeFile(*(root.get()), out)))    //这里不能有封号， 切记 切记 切记！！！！！
  {
    osg::notify(osg::FATAL) << "Failed in osgDB::writeNodeFile()." << std::endl;
    //return 1;
  }

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

  osgViewer::Viewer viewer;
  viewer.setSceneData(osgDB::readNodeFile("Text.osg"));
  return viewer.run();

  /*osg::ref_ptr<osgViewer::View> viewer = new osgViewer::View;
  auto node = osgDB::readNodeFile("Text.osg");
  return viewer.run();*/

  return 0;
}