glAttachShader 3G
glAttachShader attach a shader object to a program object

## C Specification

void `glAttachShader` GLuint program GLuint shader

## Parameters

program

  Specifies the program object to which a shader object will be attached.

shader

  Specifies the shader object that is to be attached.

## Description

In order to create an executable, there must be a way to specify the list of things that will be linked together. Program objects provide this mechanism. Shaders that are to be linked together in a program object must first be attached to that program object. `glAttachShader` attaches the shader object specified by shader to the program object specified by program. This indicates that shader will be included in link operations that will be performed on program.

All operations that can be performed on a shader object are valid whether or not the shader object is attached to a program object. It is permissible to attach a shader object to a program object before source code has been loaded into the shader object or before the shader object has been compiled. Multiple shader objects of the same type may not be attached to a single program object. However, a single shader object may be attached to more than one program object. If a shader object is deleted while it is attached to a program object, it will be flagged for deletion, and deletion will not occur until glDetachShader is called to detach it from all program objects to which it is attached.

## Errors

`GL_INVALID_VALUE` is generated if either program or shader 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 shader is not a shader object.

`GL_INVALID_OPERATION` is generated if shader is already attached to program, or if another shader object of the same type as shader is already attached to program.

## Associated Gets

glGetAttachedShaders with the handle of a valid program object

glIsProgram

glIsShader

## See Also

glCompileShader, glDetachShader, glLinkProgram, glShaderSource, glShaderBinary

## Copyright

Copyright 2003-2005 3Dlabs Inc. Ltd. 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/.