Bresenham's line algorithm in rust


Yesterday, I implemented Bresenham’s line algorithm for the n-th time.

It’s for my molecule viewer, working title: laurel. Here’s some progress posts.

Image of a protein rendered with my program. Black background, colorful rainbow dots indicate atoms, and grey lines between the atoms represent bonds. This protein (pdb id: 4jhw) is an RSV glycoprotein or something.

Here, you can see a protein model (pdb id: 4hjw) where the bonds are rendered using this line algorithm. (post)

To keep myself from reinventing the correct and nice way to implement this algorithm, I make this note here.

For quick reference, here is my way of doing it as of the date of publishing.

fn line(screen: &mut Screen, x0: u32, y0: u32, x1: u32, y1: u32, px: [u8; 4]) {
    let dx = i32::abs(x1 as i32 - x0 as i32);
    let dy = i32::abs(y1 as i32 - y0 as i32);
    let sx = if x0 < x1 { 1 } else { -1 };
    let sy = if y0 < y1 { 1 } else { -1 };

    let mut error = if dx > dy { dx } else { -dy } / 2;
    let mut x = x0 as i32;
    let mut y = y0 as i32;
    loop {
        screen.set_pixel(x as u32, y as u32, px);

        if x == x1 as i32 && y == y1 as i32 {

        let e = error;
        if e > -dx {
            error -= dy;
            x += sx;
        if e < dy {
            error += dx;
            y += sy;