Cool stuff. Have you considered a non-FFP solution? Withthis, you could have more than 8 lights.
Also, there are alternative shader-based non-FFP rendering methods like Forward+ that have already successfully been implemented in OSG-based tools that offer a large number of lights with good performance: https://www.youtube.com/watch?v=LHzNpAb_GjI&app=desktop On Fri, Oct 23, 2015 at 9:58 AM, Jannik Heller <[email protected]> wrote: > Hi OSG friends, > > I will be wrapping up my OpenMW port to OpenSceneGraph soon and wanted to > share a few things with you that I learned along the way. One such thing is > the lighting system that I wrote. If you do a quick search on the mailing > list, you will see that the OpenGL fixed pipeline supports a maximum of 8 > simultaneous lights and OSG inherits this limit. I have a lot more lights > in my scenes, so I had to come up with a solution. > > What I ended up with is a new lighting system, that allows you to place > any number of light sources in the scene graph, but then prior to rendering > a particular model will set the 8 closest lights as the OpenGL lights. This > is implemented as CullCallback for the individual models, pushing a > StateSet with the correct lights onto the CullVisitor. I also needed to > implement a custom StateAttribute for the light state, this is because when > applying lights OpenGL multiplies the position specified with the current > modelView matrix (which is no problem when you apply lights at beginning of > frame like OSG does, but in my case the lights are applied in between > renderning of models,Ii need to apply the lights in world space rather than > relative to that model). The solution was to write a custom light > StateAttribute that resets the modelView matrix to just the view matrix > before applying the state, then reset again to modelView when done. > > The code is here and it should be easily adaptable to your own > applications: > > > https://github.com/OpenMW/openmw/blob/master/components/sceneutil/lightmanager.cpp > > https://github.com/OpenMW/openmw/blob/master/components/sceneutil/lightmanager.hpp > > Usage is pretty straight forward: > > - Decorate your scene graph with a LightManager node. > - Create any number of LightSource's in the scene graph. The lightNum of > the contained lights do not matter as they are not used. > - Make sure that you have Mask_Lit (1<<16) in your update and cull masks > where lighting is desired. > - Add some LightListCallback's as CullCallback in your scene graph. Where > you put the callbacks determines the granularity of the light lists, so can > have an impact on visuals and performance. I recommend adding the callback > onto individual model(s) (but not necessarily individual Drawable's as that > would be slower). > > You can also combine the LightManager with regular OSG lighting. For > example, if you need a "global" directional light in your scene that is > always active, you can create it as a regular osg::LightSource and tell the > LightManager to skip over it, using setStartLight(1). This would mean the > LightManager is only managing lights 1-7 rather than all 8. > > Hope this might be useful to some OSG users as it took me a while to put > together. I did find a previous topic about the subject ( > http://forum.openscenegraph.org/viewtopic.php?t=8325&view=previous ) but > no satisfying solution was posted. > > I wonder if there is enough interest, could this turn into an official OSG > example? Or even a new NodeKit or part of the core scene graph? > > By the way, I am super impressed that I was able to implement this feature > without changing one line of code within OSG - the flexibility you get with > the various visitors and callbacks is amazing. A big kudos goes to Robert > for making the OSG so extensible! > > Cheers, > Jannik > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=65420#65420 > > > > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > -- Chris 'Xenon' Hanson, omo sanza lettere. [email protected] http://www.alphapixel.com/ Training • Consulting • Contracting 3D • Scene Graphs (Open Scene Graph/OSG) • OpenGL 2 • OpenGL 3 • OpenGL 4 • GLSL • OpenGL ES 1 • OpenGL ES 2 • OpenCL Legal/IP • Code Forensics • Digital Imaging • GIS • GPS • osgEarth • Terrain • Telemetry • Cryptography • LIDAR • Embedded • Mobile • iPhone/iPad/iOS • Android @alphapixel <https://twitter.com/alphapixel> facebook.com/alphapixel (775) 623-PIXL [7495]
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