Macro processing::create_uniforms

macro_rules! create_uniforms {
    ($screen:ident) => { ... };
    ($screen:ident, $($uniformName:ident: $value:expr),+) => { ... };
}

This macro rolls your custom uniforms for your custom shader into the uniform format expected by glium. It makes things more convienent, because it will add the current MVP transformation matrix that is shared across all shaders for consistent rendering to the screen. If your shader will be rendering 2-dimensional or 3-dimensional shapes to the screen, you will probably want to make use of this matrix, which will be available as uniform mat4 MVP in your custom shader.