glUseProgram — Installs a program object as part of current rendering state
void glUseProgram( | GLuint program); |
programSpecifies the handle of the program object whose executables are to be used as part of current rendering state.
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.
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.
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.
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
glAttachShader, glBindAttribLocation, glCompileShader, glCreateProgram, glDeleteProgram, glDetachShader, glLinkProgram, glUniform, glValidateProgram, glVertexAttrib
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/.