precision mediump float;

out vec2 uv;

void main()
{
    float x = float(((uint(gl_VertexID) + 2u) / 3u)%2u);
    float y = float(((uint(gl_VertexID) + 1u) / 3u)%2u);

    gl_Position = vec4(-1.0f + x*2.0f, -1.0f+y*2.0f, 0.0f, 1.0f);
    uv = vec2(x, y);
}