- set rasterization mode



C SPECIFICATION


PARAMETERS

       _param1  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, _param1, which can assume one  of  three  prede-
       fined values:

       GL_RENDER       Render  mode.  Primitives  are rasterized,
                       producing pixel fragments, which are writ-
                       ten  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 ren-
       der  mode  at the time glRenderMode is called, rather than
       by _param1.  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 buffer.

       GL_FEEDBACK     The number of values (not vertices) trans-
                       ferred to the feedback buffer.

       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 exe-
       cuted between the execution of glBegin and the correspond-
       ing execution of glEnd.


ASSOCIATED GETS

       glGet with argument GL_RENDER_MODE


SEE ALSO

       glFeedbackBuffer,  glInitNames, glLoadName, glPassThrough,
       glPushName, glSelectBuffer



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