I'm trying to build the latest vtk from cvs and I get the following error in vtkgl.h: c:\...\vtkgl.h(10289) : error C2065: 'GL_COMPARE_R_TO_TEXTURE_ARB' : undeclared identifier I'm building with visual studio .net 2003 on windows 2000 with cmake 2.4.7. Has anyone else had this problem? Mark Richardson