GLGETPROGRAMINTERFAC(3G)					   OpenGL Manual					  GLGETPROGRAMINTERFAC(3G)

NAME

       glGetProgramInterface - query a property of an interface in a program

C SPECIFICATION

       void glGetProgramInterfaceiv(GLuint program, GLenum programInterface, GLenum pname, GLint * params);

PARAMETERS

       program
	   The name of a program object whose interface to query.

       programInterface
	   A token identifying the interface within program to query.

       pname
	   The name of the parameter within programInterface to query.

       params
	   The address of a variable to retrieve the value of pname for the program interface.

DESCRIPTION

       glGetProgramInterfaceiv queries the property of the interface identifed by programInterface in program, the property name of which is given
       by pname.

       program must be the name of an existing program object.	programInterface is the name of the interface within program to query and must be
       one of the following values:

       GL_UNIFORM
	   The query is targeted at the set of active uniforms within program.

       GL_UNIFORM_BLOCK
	   The query is targeted at the set of active uniform blocks within program.

       GL_ATOMIC_COUNTER_BUFFER
	   The query is targeted at the set of active atomic counter buffer binding points within program.

       GL_PROGRAM_INPUT
	   The query is targeted at the set of active input variables used by the first shader stage of program. If program contains multiple
	   shader stages then input variables from any stage other than the first will not be enumerated.

       GL_PROGRAM_OUTPUT
	   The query is targeted at the set of active output variables produced by the last shader stage of program. If program contains multiple
	   shader stages then output variables from any stage other than the last will not be enumerated.

       GL_VERTEX_SUBROUTINE, GL_TESS_CONTROL_SUBROUTINE, GL_TESS_EVALUATION_SUBROUTINE, GL_GEOMETRY_SUBROUTINE, GL_FRAGMENT_SUBROUTINE,
       GL_COMPUTE_SUBROUTINE
	   ,
			   ,
			   ,
			   ,
			   ,
			   The query is targeted at the set of active subroutines for the vertex, tessellation control, tessellation evaluation,
	   geometry, fragment and compute shader stages of program, respectively.

       GL_VERTEX_SUBROUTINE_UNIFORM, GL_TESS_CONTROL_SUBROUTINE_UNIFORM, GL_TESS_EVALUATION_SUBROUTINE_UNIFORM, GL_GEOMETRY_SUBROUTINE_UNIFORM,
       GL_FRAGMENT_SUBROUTINE_UNIFORM, GL_COMPUTE_SUBROUTINE_UNIFORM
	   ,
			   ,
			   ,
			   ,
			   ,
			   The query is targeted at the set of active subroutine uniform variables used by the vertex, tessellation control,
	   tessellation evaluation, geometry, fragment and compute shader stages of program, respectively.

       GL_TRANSFORM_FEEDBACK_VARYING
	   The query is targeted at the set of output variables from the last non-fragment stage of program that would be captured if transform
	   feedback were active.

       GL_BUFFER_VARIABLE
	   The query is targeted at the set of active buffer variables used by program.

       GL_SHADER_STORAGE_BLOCK
	   The query is targeted at the set of active shader storage blocks used by program.

       pname identifies the property of programInterface to return in params.

       If pname is GL_ACTIVE_RESOURCES, the value returned is the number of resources in the active resource list for programInterface. If the
       list of active resources for programInterface is empty, zero is returned.

       If pname is GL_MAX_NAME_LENGTH, the value returned is the length of the longest active name string for an active resource in
       programInterface. This length includes an extra character for the null terminator. If the list of active resources for programInterface is
       empty, zero is returned. It is an error to specify GL_MAX_NAME_LENGTH when programInterface is GL_ATOMIC_COUNTER_BUFFER, as active atomic
       counter buffer resources are not assigned name strings.

       If pname is GL_MAX_NUM_ACTIVE_VARIABLES, the value returned is the number of active variables belonging to the interface block or atomic
       counter buffer resource in programInterface with the most active variables. If the list of active resources for programInterface is empty,
       zero is returned. When pname is GL_MAX_NUM_ACTIVE_VARIABLES, programInterface must be GL_UNIFORM_BLOCK, GL_ATOMIC_COUNTER_BUFFER, or
       GL_SHADER_STORAGE_BLOCK.

       If pname is GL_MAX_NUM_COMPATIBLE_SUBROUTINES, the value returned is the number of compatible subroutines belonging to the active
       subroutine uniform in programInterface with the most compatible subroutines. If the list of active resources for programInterface is empty,
       zero is returned. When pname is GL_MAX_NUM_COMPATIBLE_SUBROUTINES, programInterface must be one of GL_VERTEX_SUBROUTINE_UNIFORM,
       GL_TESS_CONTROL_SUBROUTINE_UNIFORM, GL_TESS_EVALUATION_SUBROUTINE_UNIFORM, GL_GEOMETRY_SUBROUTINE_UNIFORM, GL_FRAGMENT_SUBROUTINE_UNIFORM,
       or GL_COMPUTE_SUBROUTINE_UNIFORM.

ERRORS

       GL_INVALID_ENUM is generated if identifier is not one of the accepted object types.

       GL_INVALID_VALUE is generated if program is not the name of an existing sync object.

       GL_INVALID_VALUE is generated if bufSize is zero.

       If not NULL, length and label should be addresses to which the client has write access, otherwise undefined behavior, including process
       termination may occur.

ASSOCIATED GETS

       glGet() with argument GL_MAX_LABEL_LENGTH.

SEE ALSO

       glPushDebugGroup(), glPopDebugGroup(), glObjectLabel(), glGetObjectLabel().

COPYRIGHT

       Copyright (C) 2012 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							    06/10/2014						  GLGETPROGRAMINTERFAC(3G)