NAME

       glUseProgram - Installs 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 an executable that will run on the vertex processor if it
       contains one or more shader objects of type GL_VERTEX_SHADER that have been successfully
       compiled and linked. A program object will contain an executable that will run on the
       geometry processor if it contains one or more shader objects of type GL_GEOMETRY_SHADER
       that have been successfully compiled and linked. Similarly, a program object will contain
       an executable that will run on the fragment processor if it contains one or more shader
       objects of type GL_FRAGMENT_SHADER that have 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 zero, then the current rendering state refers to an invalid program object
       and the results of shader execution are undefined. However, this is not an error.

       If program does not contain shader objects of type GL_FRAGMENT_SHADER, an executable will
       be installed on the vertex, and possibly geometry processors, but the results of fragment
       shader execution will be undefined.

NOTES

       Like buffer and texture 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.

       GL_INVALID_OPERATION is generated if transform feedback mode is active.

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

       glGetProgram() 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/.

AUTHORS

       opengl.org