Specifies which texture unit to make active. The number
of texture units is implementation dependent, but must be at least
two. texture must be one of GL_TEXTURE$i$_ARB, where
0 < $ i $ < GL_MAX_TEXTURE_UNITS_ARB, which is an
implementation-dependent value. The initial value is GL_TEXTURE0_ARB.
DESCRIPTION
glActiveTextureARB selects which texture unit subsequent texture state calls will
affect. The number of texture units an implementation supports is
implementation dependent, but must be at least 2.
Vertex arrays are client-side GL resources, which are selected by the
glClientActiveTextureARB routine.
NOTES
glActiveTextureARB is only supported if GL_ARB_multitexture is included in the
string returned by glGetString when called with the argument
GL_EXTENSIONS.
ERRORS
GL_INVALID_ENUM is generated if texture is not one of
GL_TEXTURE$i$_ARB,
where 0 < $ i $ < GL_MAX_TEXTURE_UNITS_ARB.
