//use Reinhard operator to determine new color
Color PostProcess::ToneMap(const Color &c, float avLum,float middleGrey,float whitePoint)
{
float colorLum=CalculateLuminance(c);
float scaledLum=(colorLum*middleGrey)/avLum;
float compLum=(scaledLum*(1+(scaledLum/(whitePoint*whitePoint))))/(1+scaledLum);
return c*compLum;
}
//logarithmic average of luminance
float PostProcess::CalculateAverageLum(const PixelBuff *c)
{
double result=0;
for(int i=0;i<c->Width();++i)
for(int j=0;j<c->Height();++j)
result+=log(1e-5+CalculateLuminance(c->GetColor(i,j)));
result/=c->Width()*c->Height();
return static_cast<float>(exp(result));
}
//compresses dark pixel, leaves bright areas
PixelBuff* PostProcess::BrightPass(const PixelBuff *source, float middleGrey,float whitePoint,
float treshold,float offset)
{
float avLum=PostProcess::CalculateAverageLum(source);
PixelBuff* dst=new PixelBuff(source->Width(),source->Height());
for(int i=0;i<source->Width();++i)
for(int j=0;j<source->Height();++j)
{
float colorLum=CalculateLuminance(source->GetColor(i,j));
float scaledLum=(colorLum*middleGrey)/avLum;
float tmp=scaledLum*(1+scaledLum/(whitePoint*whitePoint))-treshold;
tmp=tmp>0?tmp:0;
dst->SetColor(i,j,(tmp/(offset+tmp))*source->GetColor(i,j));
}
return dst;
}
CompositorPtr HDRCompositor::Create(void)
{
m_Compositor = CompositorManager::getSingleton().create("HDR", ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME);
m_HDRTechnique = m_Compositor->createTechnique();
m_HDRTechnique->setCompositorLogicName("HDR");
CompositionTechnique::TextureDefinition *texdef = m_HDRTechnique->createTextureDefinition("Scene");
texdef->refTexName = "mrt_output";
texdef->refCompName="gbuffer";
// texdef->scope=Ogre::CompositionTechnique::TextureScope::TS_GLOBAL;
//render scene
// CreateTextureDef("Scene",0,0,PF_FLOAT16_RGB);
// CompositionTargetPass *tp = m_HDRTechnique->createTargetPass();
// tp->setInputMode(CompositionTargetPass::IM_PREVIOUS);
// tp->setOutputName("Scene");
RenderDownSample();
CalculateLuminance();
CalculateKey();
if(m_GlareType || m_StarType)
{
BrightPass();
if(m_GlareType)
BuildGlare();
if(m_StarType)
BuildStar();
}
if(m_ToneMapper == TM_REINHARDLOCAL)
BuildScales();
FinalRendering();
return m_Compositor;
}