glUseProgram — Installs a program object as part of current rendering state
| ||GLuint program |
Specifies 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 a shader object of type
GL_VERTEX_SHADER that has been successfully compiled and linked. Similarly, a program object will contain an executable that will run on the fragment processor if it contains a shader object of type
GL_FRAGMENT_SHADER that has 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.
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.
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 and not paused.
glGet with the argument
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
|OpenGL ES API Version|
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