Hello,
I'm trying to implement an advanced HDR lighting algorithm where I need
the average luminance of the last frame(s).
Currently I've encountered two major problems:
1. Is there a possibility to get only the last mipmap-level from
texture/image bound to a FBO?
I can get the whole image via readImageFromCurrentTexture in a
postDrawCallback, but this unfortunately copies the complete texture.
Looking at the code, I see that all mipmap levels are copied, and my
question is if it would be feasible to either create a special function
to copy only a specific mipmap-level or add an additional parameter to
the function to specifiy the mipmap level?
2. I have trouble getting correct values from floating point buffers. It
works if get the values as GL_UNSIGNED_BYTE (the values are indeed
scaled to 0 -255) but this, of course, won't be precise enough as the
buffer holds the logarithmic luminance.
Below you find a snippet of my PostDrawCallback, maybe I'm doint
something fundamentally wrong.
I'm running on OSG 3.0.1.
virtual void operator () (osg::RenderInfo& render_info) const
{
//state->apply(render_info.getCurrentCamera()->getStateSet());
//state->applyTextureAttribute(0,mTexture);
//mTexture->apply(*state);
osg::ref_ptr<osg::Image> image=new osg::Image();
mTexture->getImage()->readImageFromCurrentTexture(render_info.getContextID(),true,
GL_UNSIGNED_BYTE); //works , doesn't work with GL_FLOAT
double data = *image->getMipmapData(0);
std::cout << "luminance " << data << std::endl;
//osgDB::writeImageFile(*image,"snap.bmp");
}
cheers
Sebastian
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