On Mon, 2007-11-12 at 19:41 +0000, Robert Osfield wrote: > Hi Jeremy, > > I wouldn't worry about users defined clip planes, or special texture > matrix set up. I suggest getting to grips with plain OpenGL modelview > and projection matrices and how they work, the OSG's Camera view and > projection matrices map directly to OpenGL's so docs on the web and > OpenGL books on the topic of cameras should help you. Once you grasp > this stuff hopefully things will become second nature and the > solutions will pop out of this better understanding. I'm no great > educator though, so I have to defer to other texts for this, but I do > know that the time you invest in understanding modelview and > projection matrices will repay you many time over throughout the rest > of your career.
:) Well, I wouldn't go so far as to say I don't have ANY understanding of those concepts--it's just that translating your recommendation into implementation isn't immediately obvious given both my understanding of GL in general and my familiarity with OSG. At any rate, introducing clipping may solve the issue of not rendering the undesirable portions of a piece of a geometry, but how does it affect picking? Is it possible to pick objects that are clipped (this seems to be the case from my small tests here, though I'm probably doing something wrong)... > Robert. > > On Nov 12, 2007 7:03 PM, Jeremy L. Moles <[EMAIL PROTECTED]> wrote: > > > > On Mon, 2007-11-12 at 18:17 +0000, Robert Osfield wrote: > > > The most flexible approach would be to use a Camera that moves over > > > the 2D subgraph using the view frustum to clip out what you don't need > > > to see on screen. The Camera could be a straight HUD camera and > > > render on top or a RTT Camera, the later would have the added > > > flexibility of rendering onto 3D objects, but this is really an > > > orthogonal issue, once you have a Camera for rendering you scrollable > > > view you are done. For the scrolling you could either update the view > > > matrix or the projection matrix, personally I'd update the view matrix > > > as one can then think of scolling as panning across a scene and even > > > use camera manipulators for it > > > > Well, I must admit that a lot of what you're saying here I'm familiar > > with in concept but not in implementation. For example, I've never > > worked directly with setting Clipping Planes in OpenGL, and I don't > > think interfacing with them is non-trivial. Hell, I wouldn't even know > > where to begin to find out how to calculate the necessary A, B, C, and D > > values for my 2D Orthographic projection, nor do I have any > > understanding of the complications with regards to how a clipping pane > > is affected by the current matrices and how they are affected by state > > (there are some previous posts on this in my archives). > > > > Looks like I may need to go back to formula and review some core > > concepts... > > > > > > > _______________________________________________ > > > osg-users mailing list > > > [email protected] > > > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > > > > > > > _______________________________________________ > > osg-users mailing list > > [email protected] > > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > > > _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
