Hi Bram,
Deferred Shading or rendering to MRT doesn't support standard
multi-sampling, as the MSAA is only used in the frame buffer resolve.
There are however multiple options.
1. Make all RenderTargets multisampled and use sampler2DMS and
texelFetch( sampler, texcoord, sample ) in your shaders.
2. Use super-sampling, i.e. your render target is bigger than your
actual display resolution (2048x2048 vs. 1024x1024)
3. Use postprocessing anti-aliasing. Deferred shading gives you an
advantage here, as you usually have the normal and depth information
ready to use it for sophisticated edge detection.
4. Rely on built in post-processing anti-aliasing such as FXAA on nvidia
cards.
When choosing 1) there are some serious drawbacks. You will have to make
most targets from your gbuffer pass multisampled and thus having a much
higher load on the fragment shaders and bandwith.
There are some techniques to multi-sample only fragments that are on an
edge, but still there will be a lot of work.
Use you preferred internet search to find some papers and other docs
about multi-sampling and deferred shading/lighting.
Option 2) will also be fairly limited, as it will produce really good
antialiasing only if you have like 4 times oversampling (so 1920x1080
would be 8192x8192, which is a guaranteed killer on most GPUs)
I personally use a mix of 2) and 3) for projects where quality doesn't
have to be excellent
Option 1) is the best, but is slow if done naively.
cheers
Sebastian
P.S.
Search the mail archive, there are some question of mine regarding the
multi sampled buffer setup.
When I switched from 'normal' rendering to deferred rendering (or how you call
it) I noticed a difference in how it looked, while it should look the same.
I believe now that it looks different because I use setNumMultiSamples
Code:
osg::DisplaySettings::instance()->setNumMultiSamples( 4 );
But in the render to multiple-textures it does not seem to do this. Is it even
possible to do this?
I write colors, normals and world coodinates to 3 different buffers, so I
wouldn't really know if it's possible to do multi sampling on that (does it
also multi sample the normals etc. then?)
Anyone who can tell me more about this?
Thanks a lot!
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=54201#54201
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