Hi guys!
I try to implement HDR. And I got some problem when I compute average
luminance
I have to render it to 1X1 texture and here is the main problem
When I setup viewport with setVewport(0,0,1,1) - I've got clearcolor i.e.
(1,0,0,0)
When I setup viewport with setVewport(0,0,2,2) - I've got average luminance
- but here I've got 2X2 texture but I need 1X1 texture
What should I do?
Here is my source (luminance2 texture has size of 4X4)
osg::ref_ptr<osg::Texture2D> finalluminance = new osg::Texture2D;
finalluminance->setTextureSize( 2, 2);
finalluminance->setInternalFormat(GL_RGBA16F_ARB);
finalluminance->setSourceFormat(GL_RGBA);
finalluminance->setSourceType(GL_FLOAT);
finalluminance->setFilter(osg::Texture2D::MIN_FILTER,osg::Texture2D::LINEAR)
;
finalluminance->setFilter(osg::Texture2D::MAG_FILTER,osg::Texture2D::LINEAR)
;
finalluminance->setWrap(osg::Texture::WRAP_S,
osg::Texture::CLAMP);
finalluminance->setWrap(osg::Texture::WRAP_T,
osg::Texture::CLAMP);
osg::ref_ptr<osg::Camera> luminance3Camera = new osg::Camera;
osg::ref_ptr<osg::Geode> geode = new osg::Geode;
osg::ref_ptr<osg::Geometry> geom
=osg::createTexturedQuadGeometry(osg::Vec3(0,0,-1),osg::Vec3(1.0,0.0,-1.0),o
sg::Vec3(0.0,1.0,-1.0));
geom->getOrCreateStateSet()->setMode(GL_LIGHTING,osg::StateAttribute::OFF);
geode->addDrawable(geom.get());
luminance3Camera->setName("luminance3");
luminance3Camera->setClearColor(osg::Vec4f(1.0f,0.0f,0.0f,1.0f));
luminance3Camera->setProjectionMatrix(osg::Matrix::ortho2D(0,1,0,1));
luminance3Camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
luminance3Camera->setViewMatrix(osg::Matrix::identity());
luminance3Camera->setViewport(0,0,2,2);
luminance3Camera->setRenderOrder(osg::Camera::POST_RENDER,13);
luminance3Camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OB
JECT);
luminance3Camera->attach(osg::Camera::COLOR_BUFFER,finalluminance.get());
luminance3Camera->addChild(geode.get());
osg::ref_ptr<osg::StateSet> luminance3stateset
=luminance3Camera->getOrCreateStateSet();
luminance3stateset->setTextureAttributeAndModes(0,luminance2.get(),osg::Stat
eAttribute::ON);
luminance3stateset->setAttribute(clamp,
osg::StateAttribute::ON);
root->addChild(luminance3Camera.get());
osg::Program* luminance3prg = new osg::Program;
luminance3stateset->setAttribute(luminance3prg);
luminance3prg->addShader(osg::Shader::readShaderFile(osg::Shader::VERTEX,
osgDB::findDataFile("Shaders/downLumExp_vp.glsl")));
luminance3prg->addShader(osg::Shader::readShaderFile(osg::Shader::FRAGMENT,
osgDB::findDataFile("Shaders/downLumExp.glsl")));
osg::Uniform* DownSampler = new
osg::Uniform("DownSampler",0);
luminance3stateset->addUniform(DownSampler);
here is downLumExp.glsl
/*FRAGMENT_SHADER*/
uniform sampler2D DownSampler;
const vec2 samples[16]={
-0.375, -0.375, -0.125, -0.375, 0.125, -0.375, 0.375, -0.375, -0.375,
-0.125, -0.125, -0.125, 0.125, -0.125, 0.375, -0.125, -0.375, 0.125, -0.125,
0.125, 0.125, 0.125, 0.375, 0.125, -0.375, 0.375, -0.125, 0.375, 0.125,
0.375, 0.375, 0.375
};
void main(void)
{
float lum = 0.0;
float maximum = 0.0;
vec4 color;
vec2 sample;
for(int i = 0; i < 16; i++)
{
sample = vec2(samples[i].x,samples[i].y);
color = texture2D(DownSampler, gl_TexCoord[0].xy + sample);
maximum = max( maximum, color.g );
lum += color.r;
}
lum *= 0.0625;
lum = exp(lum);
gl_FragColor = vec4(lum, maximum, 0.0, 1.0);
}
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