pub fn preset_xy_to_clip(x: f64, y: f64) -> [f32; 2]
Convert MD2 preset-space (x, y) (origin top-left, range [0, 1]) into clip-space (x', y') (origin centre, range [-1, 1], Y-up).
(x, y)
[0, 1]
(x', y')
[-1, 1]