gluNurbsCallback

gluNurbsCallback: man2/gluNurbsCallback.xml

gluNurbsCallback is used to define a callback to be used by a NURBS object. If the specified callback is already defined, then it is replaced. If CallBackFunc is null, then this callback will not get invoked and the related data, if any, will be lost. Except the error callback, these callbacks are used by NURBS tessellator (when GLU_NURBS_MODE is set to be GLU_NURBS_TESSELLATOR ) to return back the OpenGL polygon primitives resulting from the tessellation. Note that there are two versions of each callback: one with a user data pointer and one without. If both versions for a particular callback are specified then the callback with the user data pointer will be used. Note that `userData'' is a copy of the pointer that was specified at the last call to gluNurbsCallbackData. The error callback function is effective no matter which value that GLU_NURBS_MODE is set to. All other callback functions are effective only when GLU_NURBS_MODE is set to GLU_NURBS_TESSELLATOR. The legal callbacks are as follows:

gluNurbsCallback is available only if the GLU version is 1.2 or greater. GLU version 1.2 supports only the GLU_ERROR parameter for which. The GLU_ERROR value is deprecated in GLU version 1.3 in favor of GLU_NURBS_ERROR. All other accepted values for CallBackFunc are available only if the GLU version is 1.3 or greater.