Hi Eron, The osgUtil::Tessellator is written with one off usage in mind, so the scheme you are using is something I haven't personally tested, it may or may not work. The glu tessellation code itself may or may not be a problem too. You'll need to dig deeper in the code to see if its making any assumptions that might trigger a bug.
Robert. On Nov 29, 2007 9:42 PM, Eron Steger <[EMAIL PROTECTED]> wrote: > I have a polygon managed by a osg::Geometry object that is interactively > modified by the user. Currently, only the point's positions are > modified, not the number of points or any other attributes. Each time a > point is modified, a call to retessellatePolygon is made on a > tessellator object. The same Tessellator object is used multiple times > for each modification. > > Normally, this appears to work as expected, that is, it tessellates the > object. However if I create a quad, and move one corner to the opposite > corner, collapsing it into a shape that looks like two lines, the > polygon is no longer drawn even after the shape is modified so it's no > longer collapsed. If you are using a fixed-point font, the following > ASCII diagram shows approximately how the shape is being modified: > > a b a,d b > +---+ +----+ > | | --> | > +---+ + > c d c > > I get this behavior both with tessellation types TESS_TYPE_GEOMETRY and > TESS_TYPE_DRAWABLE. TESS_TYPE_POLYGONS seems to improperly tessellate > the polygon after some modification. > > What I want is for the tessellator to tessellate based on the original > geometry plus the modified vertex positions. Looking at how the the > osgTessellator example uses the tessellator, I figured the way I was > using it would work, but perhaps my mental model of it is flawed. Do I > need to recreate the geometry every time before I call retessellate? > > - Eron > > _______________________________________________ > 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
