On Nov 12, 2007 3:46 PM, Vladimir Shabanov <[EMAIL PROTECTED]> wrote: > 2007/11/12, Jeremy L. Moles <[EMAIL PROTECTED]>: > > 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)... > > As far as I understand no picking problems should appear when > osg::Camera's viewport is set correcly. > > You don't need to remember math for these A,B,C,D. Just use > osg::Plane( Vec3 normal, Vec3 point ) constructor. Something like > Plane( Vec3( 1,0,0 ), Vec3( x1,y1,0) ) > Plane( Vec3( 0,1,0 ), Vec3( x1,y1,0) ) > Plane( Vec3( -1,0,0 ), Vec3( x2,y2,0) ) > Plane( Vec3( 0,-1,0 ), Vec3( x2,y2,0) ) > > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
I used clip planes for a sort of 2D/3D scrolling window (a sort of spreadsheet with textures, text and some 3D models in cells). The problem I ran into was that once you have more than one scrolling window, you run into the limitation of OSG not supporting re-use of OpenGL clipping planes without setting up multiple render stages. I think there may have been a patch submitted to allow re-use of clip planes with multiple render bins, but I'm not sure of the status of that. Leif Delgass _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
