Hi, On Mon, Apr 7, 2008 at 4:13 PM, Yefei He <[EMAIL PROTECTED]> wrote: > Hi, Folks, > > This maybe OT but I'm hoping other OSG users may have worked on > the same issue. I would like to use per pixel shader lights as car > headlights in place of standard GL spotlights in my driving simulator > program based on OSG. The geometric models are loaded from external > files such as .ive or .flt models. My concern is, I don't seem to be > able to retrieve enough information for the current fragment inside > the shader. For example, some faces in a model may be set to not > to be lit, i.e. GL_LIGHTING is disabled on those faces. Is there a > way to retrieve this information from inside the shader?
Yes, you can pass it via a uniform. But if you're asking if there's a built-in uniform, no there isn't. You can see the list of built-ins (at least for GLSL 1.10) on the glsl_quickref.pdf. And in general, from the GLSL standpoint as a standard, the momentum is away from built-ins. Else it winds up as the union of every possible application's desired state being exposed as uniforms, adding burden to every shader and consuming uniform storage arrrays, which are a finite resource. -- mew > Not aware of > any method for this, I'm starting to think maybe I'll need to create > a uniform called LightingEnabled, and have it set to 1 every time > a call to glEnable(GL_LIGHTING) is made, and to 0 every time a call > to glDisable(GL_LIGHTING) is made. This seems to take place only > inside State::applyMode(mode, enabled, modestack). So, not terribly > difficult but quite clumsy. Same question exists for whether a > polygon has texture applied to it, if it is multitextured, and how > texture and base material are combined, i.e. whether it's GL_REPLACE, > GL_MODULATE, or GL_DECAL. All the GLSL tutorials I have read assumes > the user knows exactly what lighting or texturing mode he/she wants, > instead of retrieving the settings from the pipeline inside the > shader. Am I really reduced to modifying the core of OSG to add > uniforms and set their values whenever a relevant GL call is being > made? > > Thanks! > > Yefei > > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > -- Mike Weiblen -- Austin Texas USA -- http://mew.cx/ _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
