片元着色器之牛顿分形

#include <osgViewer/Viewer>
#include <osgDB/ReadFile>
#ifdef _DEBUG
#pragma comment(lib, "osgParticled.lib")
#pragma comment(lib, "osgQtd.lib")
#pragma comment(lib, "osgAnimationd.lib")
#pragma comment(lib, "osgManipulatord.lib")
#pragma comment(lib, "osgPresentationd.lib")
#pragma comment(lib, "OpenThreadsd.lib")
#pragma comment(lib, "osgWidgetd.lib")
#pragma comment(lib, "osgVolumed.lib")
#pragma comment(lib, "osgd.lib")
#pragma comment(lib, "osgSimd.lib")
#pragma comment(lib, "osgDBd.lib")
#pragma comment(lib, "osgFXd.lib")
#pragma comment(lib, "osgGAd.lib")
#pragma comment(lib, "osgUtild.lib")
#pragma comment(lib, "osgViewerd.lib")
#pragma comment(lib, "osgShadowd.lib")
#pragma comment(lib, "osgTextd.lib")
#pragma comment(lib, "osgTerraind.lib")
#pragma comment(lib, "osgEarthd.lib")
#pragma comment(lib, "osgEarthQtd.lib")
#pragma comment(lib, "osgEarthFeaturesd.lib")
#pragma comment(lib, "osgEarthSymbologyd.lib")
#pragma comment(lib, "osgEarthUtild.lib")
#pragma comment(lib, "osgEarthAnnotationd.lib")
#pragma comment(lib, "osgdb_osgearth_gdald.lib")
#pragma comment(lib, "osgdb_osgearth_feature_wfsd.lib")
#pragma comment(lib, "osgdb_osgearth_feature_tfsd.lib")
#pragma comment(lib, "osgdb_osgearth_feature_ogrd.lib")
#pragma comment(lib, "OpenGL32.lib")
#else
#pragma comment(lib, "osgParticle.lib")
#pragma comment(lib, "osgQt.lib")
#pragma comment(lib, "osgAnimation.lib")
#pragma comment(lib, "osgManipulator.lib")
#pragma comment(lib, "osgPresentation.lib")
#pragma comment(lib, "OpenThreads.lib")
#pragma comment(lib, "osgWidget.lib")
#pragma comment(lib, "osgVolume.lib")
#pragma comment(lib, "osg.lib")
#pragma comment(lib, "osgSim.lib")
#pragma comment(lib, "osgDB.lib")
#pragma comment(lib, "osgFX.lib")
#pragma comment(lib, "osgGA.lib")
#pragma comment(lib, "osgUtil.lib")
#pragma comment(lib, "osgViewer.lib")
#pragma comment(lib, "osgShadow.lib")
#pragma comment(lib, "osgText.lib")
#pragma comment(lib, "osgTerrain.lib")
#pragma comment(lib, "osgEarth.lib")
#pragma comment(lib, "osgEarthQt.lib")
#pragma comment(lib, "osgEarthFeatures.lib")
#pragma comment(lib, "osgEarthSymbology.lib")
#pragma comment(lib, "osgEarthUtil.lib")
#pragma comment(lib, "osgEarthAnnotation.lib")
#pragma comment(lib, "osgdb_osgearth_gdal.lib")
#pragma comment(lib, "osgdb_osgearth_feature_wfs.lib")
#pragma comment(lib, "osgdb_osgearth_feature_tfs.lib")
#pragma comment(lib, "osgdb_osgearth_feature_ogr.lib")
#endif
const std::string vs = " \
                  #version 330\n \
                  in vec2 Position; \
                  out vec2 vertCoord; \
                  void main(void) \
                  { \
                  vertCoord = Position; \
                  gl_Position = vec4(Position, 0.0, 1.0); \
                  } \
                  ";
const std::string fs = " \
                  #version 330\n \
                  in vec2 vertCoord; \
                  uniform vec3 Color1, Color2; \
                  out vec4 fragColor; \
                  \
                  vec2 f(vec2 n) \
                  { \
                  return vec2( \
                  n.x * n.x * n.x * n.x + n.y * n.y * n.y * n.y - 2 * n.x * n.x * n.y * n.y - 1, \
                  4 * n.x * n.x * n.x * n.y - 4 * n.y * n.y * n.y * n.x \
                  ); \
                  } \
                  \
                  vec2 df(vec2 n) \
                  { \
                  return 4 * vec2( \
                  n.x*n.x*n.x - 3.0*n.x*n.y*n.y, \
                  -n.y*n.y*n.y + 3.0*n.x*n.x*n.y \
                  ); \
                  } \
                  \
                  vec2 cdiv(vec2 a, vec2 b) \
                  { \
                  float d = dot(b, b); \
                  if(d == 0.0) return a; \
                  else return vec2( \
                  (a.x*b.x + a.y*b.y) / d, \
                  (a.y*b.x - a.x*b.y) / d  \
                  ); \
                  } \
                  void main(void) \
                  { \
                  vec2 z = vertCoord; \
                  int i, max = 128; \
                  for(i = 0; i != max; ++i) \
                  { \
                  vec2 zn = z - cdiv(f(z), df(z)); \
                  if(distance(zn, z) < 0.00001) break; \
                  z = zn; \
                  } \
                  fragColor = vec4( \
                  mix( \
                  Color1.rgb, \
                  Color2.rgb, \
                  float(i) / float(max) \
                  ), \
                  1.0 \
                  ); \
                  } \
                  ";


osg::ref_ptr<osg::StateSet> CreateStateSet()
{
    osg::ref_ptr<osg::StateSet> stateSet = new osg::StateSet;

    osg::ref_ptr<osg::Shader> vShader = new osg::Shader(osg::Shader::VERTEX, vs);
    osg::ref_ptr<osg::Shader> fShader = new osg::Shader(osg::Shader::FRAGMENT, fs);
    osg::ref_ptr<osg::Program> program = new osg::Program;
    program->addShader(vShader.get());
    program->addShader(fShader.get());
    program->addBindAttribLocation("Position", 0);
    osg::ref_ptr<osg::Uniform> uColor1 = new osg::Uniform("Color1", osg::Vec3(0.2f, 0.02f, 0.05f));
    osg::ref_ptr<osg::Uniform> uColor2 = new osg::Uniform("Color2", osg::Vec3(1.0f, 0.95f, 0.98f));
    stateSet->addUniform(uColor1.get());
    stateSet->addUniform(uColor2.get());
    stateSet->setAttributeAndModes(program.get(), osg::StateAttribute::ON);
    return stateSet.get();
}

osg::ref_ptr<osg::Geode> CreateGeode()
{
    osg::ref_ptr<osg::Geode> geode = new osg::Geode;
    osg::ref_ptr<osg::Geometry> geometry = new osg::Geometry;
    osg::ref_ptr<osg::Vec3Array> vArray = new osg::Vec3Array;
    osg::ref_ptr<osg::Vec2Array> aArray = new osg::Vec2Array;
    const GLfloat rectangle_verts[12] = {
        -1.0f, -1.0f, 0.0f,
        -1.0f,  1.0f, 0.0f, 
        1.0f,  1.0f, 0.0f,
        1.0f,  -1.0f, 0.0f
    };

    vArray->push_back(osg::Vec3(-1.0f, -1.0f, 0.0f));
    vArray->push_back(osg::Vec3(-1.0f, 1.0f, 0.0f));
    vArray->push_back(osg::Vec3(1.0f, 1.0f, 0.0f));
    vArray->push_back(osg::Vec3(1.0f, -1.0f, 0.0f));

    aArray->push_back(osg::Vec2(0.0, 0.0));
    
    geometry->setVertexArray(vArray.get());
    geometry->setVertexAttribArray(0, aArray.get());

    geometry->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::POLYGON, 0, vArray->size()));
    geode->addDrawable(geometry.get());

    return geode.get();
}
int main()
{
    osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer;
    osg::ref_ptr<osg::Geode> geode = CreateGeode();
    geode->setStateSet(CreateStateSet());
    viewer->setSceneData(geode.get());

    viewer->setUpViewInWindow(35, 35, 1024, 800);
    return viewer->run();
}