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.

       GL_TRANSFORM_FEEDBACK_BUFFER
           The query is targeted at the set of active buffer binding points to which output
           variables in the GL_TRANSFORM_FEEDBACK_VARYING interface are written.

       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.

       GL_INVALID_OPERATION is generated if pname is GL_MAX_NAME_LENGTH and programInterface is
       GL_ATOMIC_COUNTER_BUFFER or GL_TRANSFORM_FEEDBACK_BUFFER, since active atomic counter and
       transform feedback buffer resources are not assigned name strings.

       GL_INVALID_OPERATION error is generated if pname is GL_MAX_NUM_ACTIVE_VARIABLES and
       programInterface is not GL_UNIFORM_BLOCK, GL_SHADER_STORAGE_BLOCK,
       GL_ATOMIC_COUNTER_BUFFER, or GL_TRANSFORM_FEEDBACK_BUFFER.

       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 © 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