glUseProgram
3G

# glUseProgram

install a program object as part of current rendering state

## C Specification

    		void glUseProgram
    		GLuint program

## Parameters

`program`

  Specifies the handle of the program object whose executables are to be used as part of current rendering state.

## Description

`glUseProgram` installs the program object specified by `program` as part of current rendering state. One or more executables are created in a program object by successfully attaching shader objects to it with glAttachShader, successfully compiling the shader objects with glCompileShader, and successfully linking the program object with glLinkProgram.

A program object will contain executables that will run on the vertex and fragment processors if it contains one or more shader objects of type `GL_VERTEX_SHADER` and one or more shader objects of type `GL_FRAGMENT_SHADER` that have all been successfully compiled and linked.

While a program object is in use, applications are free to modify attached shader objects, compile attached shader objects, attach additional shader objects, and detach or delete shader objects. None of these operations will affect the executables that are part of the current state. However, relinking the program object that is currently in use will install the program object as part of the current rendering state if the link operation was successful (see glLinkProgram ). 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` is 0, then the current rendering state refers to an invalid program object, and the results of vertex and fragment shader execution due to any glDrawArrays or glDrawElements commands are undefined.

## Notes

Like texture objects and buffer objects, the name space for program objects may be shared across a set of contexts, as long as the server sides of the contexts share the same address space. If the name space is shared across contexts, any attached objects and the data associated with those attached objects are shared as well.

Applications are responsible for providing the synchronization across API calls when objects are accessed from different execution threads.

## Errors

`GL_INVALID_VALUE` is generated if `program` is neither 0 nor a value generated by OpenGL.

`GL_INVALID_OPERATION` is generated if `program` is not a program object.

`GL_INVALID_OPERATION` is generated if `program` could not be made part of current state.

## Associated Gets

glGet with the argument `GL_CURRENT_PROGRAM`

glGetActiveAttrib with a valid program object and the index of an active attribute variable

glGetActiveUniform with a valid program object and the index of an active uniform variable

glGetAttachedShaders with a valid program object

glGetAttribLocation with a valid program object and the name of an attribute variable

glGetProgramiv with a valid program object and the parameter to be queried

glGetProgramInfoLog with a valid program object

glGetUniform with a valid program object and the location of a uniform variable

glGetUniformLocation with a valid program object and the name of a uniform variable

glIsProgram

## See Also

glAttachShader, glBindAttribLocation, glCompileShader, glCreateProgram, glDeleteProgram, glDetachShader, glLinkProgram, glUniform, glValidateProgram, glVertexAttrib

## 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/.