I have a problem with the nurbs surface in OpenGL. I am not able to generate a surface with more than 24 Knot in u or V direction. This is my code for do the surface 24 X 24 that work correctly //initializa Knots knots : array[0..47]of GLfloat for i:=0 to 23 do knots:=0; for i:= 24 to 47 do knots:=1; //draw Surface gluBeginSurface(nurb); // Draw the surface using the given control points. gluNurbsSurface(nurb, 24*2, @knots[0], 24*2, @knots[0], 24*4, 4,@ctlpoints[0], 24,24, GL_MAP2_VERTEX_4); gluEndSurface(nurb); the same code for surface 26X26 don''t work: //initializa Knots knots : array[0..51]of GLfloat for i:=0 to 25 do knots:=0; for i:= 26 to 51 do knots:=1; //draw Surface gluBeginSurface(nurb); // Draw the surface using the given control points. gluNurbsSurface(nurb, 26*2, @knots[0], 26*2, @knots[0], 26*4, 4,@ctlpoints[0], 26,26, GL_MAP2_VERTEX_4); gluEndSurface(nurb); Plese Help Me to find my error Thanks Rossetti Roberto EMail: Logica.Sviluppo@arcanet.it </i>