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GLRENDERMODE(3G)                                                                            GLRENDERMODE(3G)



NAME
       glRenderMode - set rasterization mode


C SPECIFICATION
       GLint glRenderMode( GLenum mode )


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 buffer.

       GL_FEEDBACK     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
       If an error is generated, glRenderMode returns 0 regardless of the current 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 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
       glGet with argument GL_RENDER_MODE

SEE ALSO
       glFeedbackBuffer(3G), glInitNames(3G), glLoadName(3G), glPassThrough(3G), glPushName(3G), glSelectBuffer(3G)




                                                                                            GLRENDERMODE(3G)