GLRENDERMODE() MachTen Programmer’s Manual GLRENDERMODE()

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 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 glSe-
lectBuffer) 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 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) trans-
ferred 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 regard-
less 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 glRender-
Mode is called with argument GL_SELECT before glSelect-
Buffer is called at least once.

GL_INVALID_OPERATION is generated if glFeedbackBuffer is
called while the render mode is GL_FEEDBACK, or if glRen-
derMode is called with argument GL_FEEDBACK before glFeed-
backBuffer 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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