Function solium_effect_grid 

#[unsafe(no_mangle)]
pub extern "C" fn solium_effect_grid(
    index: u32,
    axis: u32,
    progress: f64,
    spread: f64,
    from_x: f64,
    from_y: f64,
    from_w: f64,
    from_h: f64,
    to_x: f64,
    to_y: f64,
    to_w: f64,
    to_h: f64,
) -> u32

Deform a window into a target and write the whole grid out.

Returns how many points were written. They are in row-major order – columns + 1 across, rows + 1 down – which is the order warp::mesh_part walks, so a page drawing quads out of this is drawing the compositor’s own cells.