void CRenderer::PostProcess()
{
	float dx = 0.5f/Width;
	float dy = 0.5f/Height;
	int loc;
	//把texColor复制到imgBloom
	ScaleCopy->ScaleCopyTextureImage(texColor,Width,Height,imgBloom); 
	
	MeasureLuminance(imgBloom); //计算imgBloom的平均亮度
	lumAdapt += (lum - lumAdapt) * ( 1 - pow( 0.98f, 30 * dTime ) ); //计算当前适应的亮度

	// render bloom map
	// progBloom由Bloom.vs和Bloom.fs组成。其代码在后面给出。这个Shader用于提取出
	UseShaderProgram(progBloom); 
	

	//接下来，把texColor渲染到imgBloom里面，使用progBloom Shader程序提取出亮度较大的部分。

	loc = gapi->Shader->GetUniformLocationARB(progBloom->ProgramID,"texColor");
	glBindTexture(GL_TEXTURE_2D,texColor);

	//设置渲染对象。
	CRenderTarget tgt;
	tgt.AddColorAttachment(imgBloom);
	SetRenderTarget(tgt);

	gapi->Shader->Uniform1iARB(loc,0);
	loc = gapi->Shader->GetUniformLocationARB(progBloom->ProgramID,"AveLum");
	gapi->Shader->Uniform1fARB(loc,lumAdapt);
	loc = gapi->Shader->GetUniformLocationARB(progBloom->ProgramID,"imgH");
	gapi->Shader->Uniform1iARB(loc,Height);
	loc = gapi->Shader->GetUniformLocationARB(progBloom->ProgramID,"imgW");
	gapi->Shader->Uniform1iARB(loc,Width);
	
	
	glBegin(GL_QUADS);
		glTexCoord2f(dx,1-dy);
		glVertex2i(0,0);
		glTexCoord2f(dx,dy);
		glVertex2i(0,imgBloom->GetHeight());
		glTexCoord2f(1-dx,dy);
		glVertex2i(imgBloom->GetWidth(),imgBloom->GetHeight());
		glTexCoord2f(1-dx,1-dy);
		glVertex2i(imgBloom->GetWidth(),0);
	glEnd();
	UseShaderProgram(0);
	ResetRenderTarget();

	// 下采样imgBloom到imgLumSample中。imgLumSample的大小为32*32。
	tgt.ColorAttachCount = 0;
	tgt.AddColorAttachment(imgLumSample);
	SetRenderTarget(tgt);
	UseShaderProgram(progDownSample8);
	loc = gapi->Shader->GetUniformLocationARB(progDownSample8->ProgramID,"imgH");
	gapi->Shader->Uniform1iARB(loc,imgBloom->GetHeight());
	loc = gapi->Shader->GetUniformLocationARB(progDownSample8->ProgramID,"imgW");
	gapi->Shader->Uniform1iARB(loc,imgBloom->GetWidth());
	loc = gapi->Shader->GetUniformLocationARB(progDownSample8->ProgramID,"texColor");
	glBindTexture(GL_TEXTURE_2D,imgBloom->GetID());
	gapi->Shader->Uniform1iARB(loc,0);
	glBegin(GL_QUADS);
		glTexCoord2f(dx,1-dy);
		glVertex2i(0,0);
		glTexCoord2f(dx,dy);
		glVertex2i(0,imgLumSample->GetHeight());
		glTexCoord2f(1-dx,dy);
		glVertex2i(imgLumSample->GetWidth(),imgLumSample->GetHeight());
		glTexCoord2f(1-dx,1-dy);
		glVertex2i(imgLumSample->GetWidth(),0);
	glEnd();

	UseShaderProgram(0);
	ResetRenderTarget();

	// 模糊Bloom贴图。BlurFilter是一个类，在GPU上执行模糊操作。
	BlurFilter->SetImage(imgLumSample);
	BlurFilter->Blur();
	imgLumSample = BlurFilter->GetImage();

	// Tone Mapping
	UseShaderProgram(progTone);
	if (!progTone->Validate())
		throw HException(progTone->Info);
	gapi->BindTexture2D(texColor,0);
	loc = gapi->Shader->GetUniformLocationARB(progTone->ProgramID,"texSrc");
	gapi->Shader->Uniform1iARB(loc,0);
	gapi->BindTexture2D(imgLumSample->GetID(),1);
	loc = gapi->Shader->GetUniformLocationARB(progTone->ProgramID,"texBloom");
	gapi->Shader->Uniform1iARB(loc,1);
	loc = gapi->Shader->GetUniformLocationARB(progTone->ProgramID,"AveLum");
	gapi->Shader->Uniform1fARB(loc,lumAdapt);
	loc = gapi->Shader->GetUniformLocationARB(progTone->ProgramID,"Key");
	gapi->Shader->Uniform1fARB(loc,HDRKey);

	glColor4ub(255,255,255,255);
	gapi->FBO->BindFramebuffer(GL_FRAMEBUFFER_EXT,0); //设置渲染对象为屏幕
	glBegin(GL_QUADS);
		glTexCoord2f(dx,1-dy);
		glVertex2i(0,0);
		glTexCoord2f(dx,dy);
		glVertex2i(0,Height);
		glTexCoord2f(1-dx,dy);
		glVertex2i(Width,Height);
		glTexCoord2f(1-dx,1-dy);
		glVertex2i(Width,0);
	glEnd();
	UseShaderProgram(0);
	gapi->BindTexture2D(0,1);
	glBindTexture(GL_TEXTURE_2D,0);
}

void CRenderer::MeasureLuminance(CGPUImage *img)
{
	// 把img渲染到imgLumSample,使用shader计算每个象素的对数值
	CRenderTarget tgt;
	tgt.AddColorAttachment(imgLumSample);
	SetRenderTarget(tgt);
	UseShaderProgram(progLogSample);
	if (!progLogSample->Validate())
		throw HException(progLogSample->Info);
	gapi->MultiTexture->ActiveTexture(GL_TEXTURE0);
	glBindTexture(GL_TEXTURE_2D,img->GetID());
	int loc = gapi->Shader->GetUniformLocationARB(progLogSample->ProgramID,"texSrc");
	gapi->Shader->Uniform1iARB(loc,0);
	glBegin(GL_QUADS);
		glTexCoord2i(0,1);
		glVertex2i(0,0);
		glTexCoord2i(0,0);
		glVertex2i(0,SampleSize);
		glTexCoord2i(1,0);
		glVertex2i(SampleSize,SampleSize);
		glTexCoord2i(1,1);
		glVertex2i(SampleSize,0);
	glEnd();
	UseShaderProgram(0);
	ResetRenderTarget();

	glBindTexture(GL_TEXTURE_2D,imgLumSample->GetID());
	//回读到CPU计算亮度。
	glGetTexImage(GL_TEXTURE_2D,0,GL_RGBA,GL_FLOAT,data);
	lum = 0;
	
	for (int i=0;i<imgLumSample->GetHeight();i++)
		for (int j=0;j<imgLumSample->GetWidth();j++)
			lum += data[i*imgLumSample->GetWidth()*4+j*4];
	lum /= imgLumSample->GetHeight()*imgLumSample->GetWidth();
	lum = exp(lum);
}