PARAMETERS
       mode  Specifies  the  rasterization  mode.   Three  values are accepted:
             GL_RENDER, GL_SELECT,  and  GL_FEEDBACK.   The  initial  value  is
             GL_RENDER.

DESCRIPTION
       glRenderMode  sets the rasterization mode.  It takes one argument, mode,
       which can assume one of three predefined values:

       GL_RENDER       Render mode. Primitives are rasterized, producing  pixel
                       fragments,  which  are  written  into  the frame buffer.
                       This is the normal mode and also the default mode.

       GL_SELECT       Selection mode.  No pixel fragments are produced, and no
                       change to the frame buffer contents is made.  Instead, a
                       record of the names of primitives that would  have  been
                       drawn  if the render mode had been GL_RENDER is returned
                       in  a  select  buffer,  which  must  be   created   (see
                       glSelectBuffer) before selection mode is entered.

       GL_FEEDBACK     Feedback  mode.  No pixel fragments are produced, and no
                       change to the frame buffer contents is  made.   Instead,
                       the  coordinates  and  attributes of vertices that would
                       have been drawn if the render mode had been GL_RENDER is
                       returned  in  a  feedback  buffer, which must be created
                       (see glFeedbackBuffer) before feedback mode is entered.

       The return value of glRenderMode is determined by the render mode at the
       time  glRenderMode  is called, rather than by mode.  The values returned
       for the three render modes are as follows:

       GL_RENDER       0.

       GL_SELECT       The number of hit records transferred to the select buf‐
                       fer.

       GL_FEEDBACK     The  number  of values (not vertices) transferred to the
                       feedback buffer.

       See the glSelectBuffer and glFeedbackBuffer reference pages for more de‐
       tails concerning selection and feedback operation.

NOTES
       If  an error is generated, glRenderMode returns 0 regardless of the cur‐
       rent render mode.

ERRORS
       GL_INVALID_ENUM is generated if mode is not one of  the  three  accepted
       values.

       GL_INVALID_OPERATION  is generated if glSelectBuffer is called while the
       glFeedbackBuffer, glInitNames,  glLoadName,  glPassThrough,  glPushName,
       glSelectBuffer

                                                               GLRENDERMODE(3G)