2005
Sams Publishing
glGetQueryObject
3G
glGetQueryObject
return parameters of a query object
C Specification
void glGetQueryObjectiv
GLuint id
GLenum pname
GLint * params
void glGetQueryObjectuiv
GLuint id
GLenum pname
GLuint * params
void glGetQueryObjecti64v
GLuint id
GLenum pname
GLint64 * params
void glGetQueryObjectui64v
GLuint id
GLenum pname
GLuint64 * params
Parameters
id
Specifies the name of a query object.
pname
Specifies the symbolic name of a query object parameter.
Accepted values are GL_QUERY_RESULT or GL_QUERY_RESULT_AVAILABLE.
params
If a buffer is bound to the GL_QUERY_RESULT_BUFFER target, then params
is treated as an offset to a location within that buffer's data store to receive the result of the query. If
no buffer is bound to GL_QUERY_RESULT_BUFFER, then params is
treated as an address in client memory of a variable to receive the resulting data.
Description
glGetQueryObject returns in params a selected parameter of the query object
specified by id.
pname names a specific query object parameter. pname can be as follows:
GL_QUERY_RESULT
params returns the value of the query object's passed samples counter.
The initial value is 0.
GL_QUERY_RESULT_NO_WAIT
If the result of the query is available (that is, a query of GL_QUERY_RESULT_AVAILABLE would
return non-zero), then params returns the value of the query object's passed samples counter,
otherwise, the data referred to by params is not modified.
The initial value is 0.
GL_QUERY_RESULT_AVAILABLE
params returns whether the passed samples counter is immediately available.
If a delay would occur waiting for the query result, GL_FALSE is returned.
Otherwise, GL_TRUE is returned, which also indicates that the results of all
previous queries are available as well.
Notes
If an error is generated,
no change is made to the contents of params.
glGetQueryObject implicitly flushes the GL pipeline so that any incomplete rendering
delimited by the occlusion query completes in finite time.
If multiple queries are issued using the same query object id before calling
glGetQueryObject, the results of the most recent query will be returned. In this case,
when issuing a new query, the results of the previous query are discarded.
glGetQueryObjecti64v and glGetQueryObjectui64v are available only
if the GL version is 3.3 or greater.
GL_QUERY_RESULT_NO_WAIT is accepted for pname only if the
GL version is 4.4 or greater.
The GL_QUERY_RESULT_BUFFER target is available only if the GL version is 4.4 or higher.
On earlier versions of the GL, params is always an address in client memory.
Errors
GL_INVALID_ENUM is generated if pname is not an accepted value.
GL_INVALID_OPERATION is generated if id is not the name of a query object.
GL_INVALID_OPERATION is generated if id is the name of a currently active
query object.
GL_INVALID_OPERATION is generated if a buffer is currently bound to the
GL_QUERY_RESULT_BUFFER target and the command would cause data to be written beyond the bounds
of that buffer's data store.
See Also
glBeginQuery,
glEndQuery,
glGetQueryiv,
glIsQuery,
glQueryCounter
Copyright
Copyright 2005 Addison-Wesley.
Copyright 2010-2013 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/.