2010 Khronos Group.
glGetActiveSubroutineUniform 3G
glGetActiveSubroutineUniform query a property of an active shader subroutine uniform

## C Specification

void `glGetActiveSubroutineUniformiv` GLuint program GLenum shadertype GLuint index GLenum pname GLint *values

## Parameters

program

  Specifies the name of the program containing the subroutine.

shadertype

  Specifies the shader stage from which to query for the subroutine parameter. shadertype must be one of `GL_VERTEX_SHADER`, `GL_TESS_CONTROL_SHADER`, `GL_TESS_EVALUATION_SHADER`, `GL_GEOMETRY_SHADER` or `GL_FRAGMENT_SHADER`.

index

  Specifies the index of the shader subroutine uniform.

pname

  Specifies the parameter of the shader subroutine uniform to query. pname must be `GL_NUM_COMPATIBLE_SUBROUTINES`, `GL_COMPATIBLE_SUBROUTINES`, `GL_UNIFORM_SIZE` or `GL_UNIFORM_NAME_LENGTH`.

values

  Specifies the address of a into which the queried value or values will be placed.

## Description

`glGetActiveSubroutineUniform` queries a parameter of an active shader subroutine uniform. program contains the name of the program containing the uniform. shadertype specifies the stage which which the uniform location, given by index, is valid. index must be between zero and the value of `GL_ACTIVE_SUBROUTINE_UNIFORMS` minus one for the shader stage.

If pname is `GL_NUM_COMPATIBLE_SUBROUTINES`, a single integer indicating the number of subroutines that can be assigned to the uniform is returned in values.

If pname is `GL_COMPATIBLE_SUBROUTINES`, an array of integers is returned in values, with each integer specifying the index of an active subroutine that can be assigned to the selected subroutine uniform. The number of integers returned is the same as the value returned for `GL_NUM_COMPATIBLE_SUBROUTINES`.

If pname is `GL_UNIFORM_SIZE`, a single integer is returned in values. If the selected subroutine uniform is an array, the declared size of the array is returned; otherwise, one is returned.

If pname is `GL_UNIFORM_NAME_LENGTH`, a single integer specifying the length of the subroutine uniform name (including the terminating null character) is returned in values.

## Errors

`GL_INVALID_ENUM` is generated if shadertype or pname is not one of the accepted values.

`GL_INVALID_VALUE` is generated if index is greater than or equal to the value of `GL_ACTIVE_SUBROUTINES`.

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

## Associated Gets

glGetProgramStage with argument `GL_ACTIVE_SUBROUTINE_UNIFORMS`

## See Also

glGetSubroutineIndex, glGetActiveSubroutineUniformName, glGetProgramStage

## Copyright

Copyright 2010 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/.