glBeginQuery — delimit the boundaries of a query object
void glBeginQuery(
|
GLenum target, |
GLuint id) ; |
void glEndQuery(
|
GLenum target) ; |
glBeginQuery
target
Specifies the target type of query object established between
glBeginQuery
and the subsequent glEndQuery
.
The symbolic constant must be one of GL_ANY_SAMPLES_PASSED
, GL_ANY_SAMPLES_PASSED_CONSERVATIVE
,
or GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN
.
id
Specifies the name of a query object.
glEndQuery
target
Specifies the target type of query object to be concluded.
The symbolic constant must be one of GL_ANY_SAMPLES_PASSED
, GL_ANY_SAMPLES_PASSED_CONSERVATIVE
,
or GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN
.
glBeginQuery
and glEndQuery delimit the
boundaries of a query object. query
must be a name previously returned from a call to
glGenQueries. If a query object with name id
does not yet exist it is created with the type determined by target
. target
must
be one of GL_ANY_SAMPLES_PASSED
, GL_ANY_SAMPLES_PASSED_CONSERVATIVE
,
or GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN
. The behavior of the query
object depends on its type and is as follows.
If target
is GL_ANY_SAMPLES_PASSED
, id
must be an unused name,
or the name of an existing boolean occlusion query object.
When glBeginQuery
is executed, the query object's samples-passed flag is reset to GL_FALSE
.
Subsequent rendering causes the flag to be set to GL_TRUE
if any sample passes the depth test. When
glEndQuery
is executed, the samples-passed flag is assigned to the query object's result value. This value can
be queried by calling glGetQueryObjectuiv with pname
GL_QUERY_RESULT
.
If target
is GL_ANY_SAMPLES_PASSED_CONSERVATIVE
, id
must be an unused name,
or the name of an existing boolean occlusion query object.
When glBeginQuery
is executed, the query object's samples-passed flag is reset to GL_FALSE
.
Subsequent rendering causes the flag to be set to GL_TRUE
if any sample passes the depth test. The implementation
may choose to use a less precision version of the test, which can additionally set the samples-passed flag to GL_TRUE
in some other implementation-dependent cases. When glEndQuery
is executed, the samples-passed flag is assigned to
the query object's result value. This value can be queried by calling glGetQueryObjectuiv
with pname
GL_QUERY_RESULT
.
If target
is GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN
, id
must be
an unused name, or the name of an existing primitive query object previously bound to the GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN
query binding. When glBeginQuery
is executed, the query object's primitives-written counter is reset to 0. Subsequent
rendering will increment the counter once for every vertex that is written into the bound transform feedback buffer(s). If transform feedback
mode is not activated between the call to glBeginQuery
and glEndQuery
, the counter will not be
incremented. When glEndQuery
is executed, the primitives-written counter is assigned to
the query object's result value. This value can be queried by calling glGetQueryObjectuiv with pname
GL_QUERY_RESULT
.
GL_INVALID_ENUM
is generated if target
is not one of the accepted tokens.
GL_INVALID_OPERATION
is generated if glBeginQuery
is executed while
a query object of the same target
is already active. Note: GL_ANY_SAMPLES_PASSED
and GL_ANY_SAMPLES_PASSED_CONSERVATIVE
alias to the same target for the purposes of this error.
GL_INVALID_OPERATION
is generated if glEndQuery
is executed when a query object of the same target
is not active.
GL_INVALID_OPERATION
is generated if id
is 0.
GL_INVALID_OPERATION
is generated if id
not a name returned from a previous call to
glGenQueries
, or if such a name has since been deleted with glDeleteQueries
.
GL_INVALID_OPERATION
is generated if id
is the name of an already active query object.
GL_INVALID_OPERATION
is generated if id
refers to an existing query object whose type
does not does not match target
.
OpenGL ES API Version | |||
---|---|---|---|
Function Name | 2.0 | 3.0 | 3.1 |
glBeginQuery
|
- | ✔ | ✔ |
glEndQuery
|
- | ✔ | ✔ |
glDeleteQueries, glGenQueries, glGetQueryiv, glGetQueryObjectuiv, glIsQuery
Copyright © 2005 Addison-Wesley. Copyright © 2010-2014 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. https://opencontent.org/openpub/.