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glRenderMode — set rasterization mode
GLint glRenderMode(GLenum mode);
mode
Specifies the rasterization mode.
Three values are accepted:
GL_RENDER,
GL_SELECT, and
GL_FEEDBACK.
The initial value is GL_RENDER.
glRenderMode sets the rasterization mode.
It takes one argument,
mode,
which can assume one of three predefined values:
GL_RENDERRender 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_RENDER0.
GL_SELECTThe number of hit records transferred to the select buffer.
GL_FEEDBACKThe 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.
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.
Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.