Of course, uniform variables can be any valid GLSL type, including complex types such as arrays or structures. OpenGL provides a glUniform function with the usual suffixes, appropriate for each type. For example, to assign to a variable of the vec3 type, one would use glUniform3f or glUniform3fv.

For arrays, one can use the functions ending in v to initialize multiple values within the array. Note that if it is desired, one can query for the location of a particular element of the uniform array using the [] operator. For example, to query for the location of the second element of MyArray:

GLuint location = 
   glGetUniformLocation( programHandle, "MyArray[1]" );

For structures, the members of the structure must be initialized individually. As with arrays, one can query for the location of a member of a structure using something like the following:

GLuint location = 
   glGetUniformLocation( programHandle, "MyMatrices.Rotation" );

Where the structure variable is MyMatrices and the member of the structure is Rotation.