Signature
Parameters
| Variables | Description |
|---|---|
| program |
Specifies the handle of the program object to be linked.
|
Description
glLinkProgram
links the program
object specified by
program
. If any
shader objects of type
GL_VERTEX_SHADER
are
attached to
program
, they will be used to
create an executable that will run on the programmable vertex
processor. If any shader objects of type
GL_GEOMETRY_SHADER
are attached to
program
, they will be used to create
an executable that will run on the programmable geometry processor.
If any shader objects of type
GL_FRAGMENT_SHADER
are attached to
program
, they will be used to create an
executable that will run on the programmable fragment
processor.
The status of the link operation will be stored as part of
the program object's state. This value will be set to
GL_TRUE
if the program object was linked
without errors and is ready for use, and
GL_FALSE
otherwise. It can be queried by
calling
glGetProgram
with arguments
program
and
GL_LINK_STATUS
.
As a result of a successful link operation, all active
user-defined uniform variables belonging to
program
will be initialized to 0, and
each of the program object's active uniform variables will be
assigned a location that can be queried by calling
glGetUniformLocation
.
Also, any active user-defined attribute variables that have not
been bound to a generic vertex attribute index will be bound to
one at this time.
Linking of a program object can fail for a number of
reasons as specified in the
OpenGL Shading Language
Specification
. The following lists some of the
conditions that will cause a link error.
The number of active attribute variables supported
by the implementation has been exceeded.
The storage limit for uniform variables has been
exceeded.
The number of active uniform variables supported
by the implementation has been exceeded.
The
main
function is missing
for the vertex, geometry or fragment shader.
A varying variable actually used in the fragment
shader is not declared in the same way (or is not
declared at all) in the vertex shader, or geometry shader if present.
A reference to a function or variable name is
unresolved.
A shared global is declared with two different
types or two different initial values.
One or more of the attached shader objects has not
been successfully compiled.
Binding a generic attribute matrix caused some
rows of the matrix to fall outside the allowed maximum
of
GL_MAX_VERTEX_ATTRIBS
.
Not enough contiguous vertex attribute slots could
be found to bind attribute matrices.
The program object contains objects to form a fragment shader but
does not contain objects to form a vertex shader.
The program object contains objects to form a geometry shader
but does not contain objects to form a vertex shader.
The program object contains objects to form a geometry shader
and the input primitive type, output primitive type, or maximum output
vertex count is not specified in any compiled geometry shader
object.
The program object contains objects to form a geometry shader
and the input primitive type, output primitive type, or maximum output
vertex count is specified differently in multiple geometry shader
objects.
The number of active outputs in the fragment shader is greater
than the value of
GL_MAX_DRAW_BUFFERS
.
The program has an active output assigned to a location greater
than or equal to the value of
GL_MAX_DUAL_SOURCE_DRAW_BUFFERS
and has an active output assigned an index greater than or equal to one.
More than one varying out variable is bound to the same number and index.
The explicit binding assigments do not leave enough space for the linker
to automatically assign a location for a varying out array, which requires
multiple contiguous locations.
The
count
specified by
glTransformFeedbackVaryings
is non-zero, but the program object has no vertex or geometry shader.
Any variable name specified to
glTransformFeedbackVaryings
in the
varyings
array is not declared as an output in the vertex shader (or the geometry shader, if active).
Any two entries in the
varyings
array given
glTransformFeedbackVaryings
specify the same varying variable.
The total number of components to capture in any transform feedback varying variable
is greater than the constant
GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_COMPONENTS
and the buffer mode is
GL_SEPARATE_ATTRIBS
.
When a program object has been successfully linked, the
program object can be made part of current state by calling
glUseProgram
.
Whether or not the link operation was successful, the program
object's information log will be overwritten. The information
log can be retrieved by calling
glGetProgramInfoLog
.
glLinkProgram
will also install the
generated executables as part of the current rendering state if
the link operation was successful and the specified program
object is already currently in use as a result of a previous
call to
glUseProgram
.
If the program object currently in use is relinked
unsuccessfully, its link status will be set to
GL_FALSE
, but the executables and
associated state will remain part of the current state until a
subsequent call to
glUseProgram
removes it
from use. After it is removed from use, it cannot be made part
of current state until it has been successfully relinked.
If
program
contains shader objects
of type
GL_VERTEX_SHADER
, and optionally of type
GL_GEOMETRY_SHADER
,
but does not contain shader objects of type
GL_FRAGMENT_SHADER
, the vertex shader executable will
be installed on the programmable vertex processor, the geometry shader executable, if present,
will be installed on the programmable geometry processor, but no executable will
be installed on the fragment processor. The results of
rasterizing primitives with such a program will be undefined.
The program object's information log is updated and the
program is generated at the time of the link operation. After
the link operation, applications are free to modify attached
shader objects, compile attached shader objects, detach shader
objects, delete shader objects, and attach additional shader
objects. None of these operations affects the information log or
the program that is part of the program object.
Notes
If the link operation is unsuccessful, any information about a previous link operation on
program
is lost (i.e., a failed link does not restore the old state of
program
). Certain information can still be retrieved from
program
even after an unsuccessful link operation. See for instance
glGetActiveAttrib
and
glGetActiveUniform
.
Errors
GL_INVALID_VALUE
is generated if
program
is not a value generated by OpenGL.
GL_INVALID_OPERATION
is generated if
program
is not a program object.
GL_INVALID_OPERATION
is generated if
program
is the currently active program
object and transform feedback mode is active.
Associated Gets
glGet
with the argument
GL_CURRENT_PROGRAM
glGetActiveAttrib
with argument
program
and the index of an active attribute variable
glGetAttachedShaders
with argument
program
glGetAttribLocation
with argument
program
and an attribute variable name
glGetProgramInfoLog
with argument
program
glGetUniform
with argument
program
and a uniform variable location
glGetUniformLocation
with argument
program
and a uniform variable name
Version Support
| glLinkProgram |
See Also
Copyright
Copyright
2003-2005 3Dlabs Inc. Ltd.
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.
http://opencontent.org/openpub/
.
Sample Code References
The following code samples have been found which appear to reference the functions described here. Take care that the code may be old, broken or not even use PyOpenGL.
glLinkProgram