glBeginConditionalRender man page on RedHat
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GLBEGINCONDITIONALRE(3G) OpenGL Manual GLBEGINCONDITIONALRE(3G)
NAME
glBeginConditionalRender - start conditional rendering
C SPECIFICATION
void glBeginConditionalRender(GLuint id, GLenum mode);
PARAMETERS
id
Specifies the name of an occlusion query object whose results are
used to determine if the rendering commands are discarded.
mode
Specifies how glBeginConditionalRender interprets the results of
the occlusion query.
C SPECIFICATION
void glEndConditionalRender(void);
DESCRIPTION
Conditional rendering is started using glBeginConditionalRender and
ended using glEndConditionalRender. During conditional rendering, all
vertex array commands, as well as glClear() and glClearBuffer() have no
effect if the (GL_SAMPLES_PASSED) result of the query object id is
zero, or if the (GL_ANY_SAMPLES_PASSED) result is GL_FALSE. The results
of commands setting the current vertex state, such as glVertexAttrib()
are undefined. If the (GL_SAMPLES_PASSED) result is non-zero or if the
(GL_ANY_SAMPLES_PASSED) result is GL_TRUE, such commands are not
discarded. The id parameter to glBeginConditionalRender must be the
name of a query object previously returned from a call to
glGenQueries(). mode specifies how the results of the query object are
to be interpreted. If mode is GL_QUERY_WAIT, the GL waits for the
results of the query to be available and then uses the results to
determine if subsequent rendering commands are discarded. If mode is
GL_QUERY_NO_WAIT, the GL may choose to unconditionally execute the
subsequent rendering commands without waiting for the query to
complete.
If mode is GL_QUERY_BY_REGION_WAIT, the GL will also wait for occlusion
query results and discard rendering commands if the result of the
occlusion query is zero. If the query result is non-zero, subsequent
rendering commands are executed, but the GL may discard the results of
the commands for any region of the framebuffer that did not contribute
to the sample count in the specified occlusion query. Any such
discarding is done in an implementation-dependent manner, but the
rendering command results may not be discarded for any samples that
contributed to the occlusion query sample count. If mode is
GL_QUERY_BY_REGION_NO_WAIT, the GL operates as in
GL_QUERY_BY_REGION_WAIT, but may choose to unconditionally execute the
subsequent rendering commands without waiting for the query to
complete.
NOTES
glBeginConditionalRender and glEndConditionalRender are available only
if the GL version is 3.0 or greater.
The GL_ANY_SAMPLES_PASSED query result is available only if the GL
version is 3.3 or greater.
ERRORS
GL_INVALID_VALUE is generated if id is not the name of an existing
query object.
GL_INVALID_ENUM is generated if mode is not one of the accepted tokens.
GL_INVALID_OPERATION is generated if glBeginConditionalRender is called
while conditional rendering is active, or if glEndConditionalRender is
called while conditional rendering is inactive.
GL_INVALID_OPERATION is generated if id is the name of a query object
with a target other than GL_SAMPLES_PASSED or GL_ANY_SAMPLES_PASSED.
GL_INVALID_OPERATION is generated if id is the name of a query
currently in progress.
SEE ALSO
glGenQueries(), glDeleteQueries(), glBeginQuery()
COPYRIGHT
Copyright © 2009 Khronos Group. This material may be distributed
subject to the terms and conditions set forth in the Open Publication
License, v 1.0, 8 June 1999. http://opencontent.org/openpub/.
AUTHORS
opengl.org
opengl.org 03/16/2013 GLBEGINCONDITIONALRE(3G)
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