NAME    [Toc]    [Back]

       glRenderMode - set rasterization mode

SYNOPSIS    [Toc]    [Back]

       GLint glRenderMode(
               GLenum mode );

PARAMETERS    [Toc]    [Back]

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

DESCRIPTION    [Toc]    [Back]

       glRenderMode()  sets  the rasterization mode. It takes one
       argument, mode, which can assume one of  three  predefined
       values:  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.  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.   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: 0.  The number of hit records transferred
  to  the  select buffer.  The number of values (not
       vertices) transferred to the feedback buffer.

       See the glSelectBuffer() and glFeedbackBuffer()  reference
       pages  for  more details concerning selection and feedback
       operation.

NOTES    [Toc]    [Back]

       If an error is generated, glRenderMode() returns 0 regardless
 of the current render mode.

ERRORS    [Toc]    [Back]

       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 render mode is GL_SELECT, or if glRenderMode()
 is called with argument GL_SELECT before  glSelectBuffer()
 is called at least once.

       GL_INVALID_OPERATION is generated if glFeedbackBuffer() is
       called while the render mode is GL_FEEDBACK, or if  glRenderMode()
  is  called  with  argument  GL_FEEDBACK  before
       glFeedbackBuffer() is called at least once.

       GL_INVALID_OPERATION is  generated  if  glRenderMode()  is
       executed  between  the  execution  of  glBegin()  and  the
       corresponding execution of glEnd().

ASSOCIATED GETS    [Toc]    [Back]

       glGet() with argument GL_RENDER_MODE

SEE ALSO    [Toc]    [Back]

       glFeedbackBuffer(3),    glInitNames(3)     ,glLoadName(3),
       glPassThrough(3), glPushName(3), glSelectBuffer(3)



                                                 glRenderMode(3G)