fn preset_xy_to_clip(x: f32, y: f32) -> [f32; 2]Expand description
MD2 preset-space → clip-space, identical to the helpers in
custom_wave / custom_shape. Origin moves from top-left at
(0, 0) to centre at (0, 0), range [0, 1] becomes [-1, 1],
and y is flipped.