Hi If you need to get same result as opengl FFP, you should add following line in your vertex shader: gl_ClipVertex = gl_ModelViewMatrix * gl_Vertex; IIRC you need #version 120 to use this. Then all clip planes enabled via glEnable would work with shaders
07.12.2011, 22:36, "Dave Jones" <[email protected]>: > Hi, > > I have some code that uses osg::ClipPlane to clip a hierarchy of meshes. All > I do is create some plane equations relative to the root node's transform and > set the planes as attributes that affect the entire tree. > > This works pretty well. When I look at the output in gDEBugger, I can see > that the clip equations are invoked after glLoadMatrix is called on the root > transform. glEnable is called on the clip planes before any of the geometry > in the hierarchy is drawn. > > Currently, I need to port this functionality to a vertex shader for a > project. Clipping in a shader is pretty straightforward, but I'm getting a > little tripped up on what transformation space the clip planes should be in > and how to transfer that to the vertex shader. > > According to the glClipPlane docs, the plane equations are transformed to > view space. In my shader, I'm passing the plane equations in as uniforms. For > this to work on all vertices, I need to ensure that the clip plane equations > have been transformed by the inverse transpose of the model view matrix. The > only way that I can think of doing that is creating a uniform update callback > which always updates the plane equations based on the camera's current model > view matrix. > > This seems a little clunky to me, but I wasn't sure how else to do it. Is > there a simpler way that I'm overlooking? This fixed function pipeline model > was convenient since it did a lot of this work for me, but it seems like I > have to do on my own if I go the programmable pipeline route. Is this a > correct assessment? > > Thanks! And sorry if this is a bit long-winded. > > -Dave > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=44278#44278 > > _______________________________________________ > 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
