glRenderMode

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 argu-
       ment 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)