raster.rs

// MIT
#[inline(always)]
pub fn line(
    &mut self,
    x0: f32,
    y0: f32,
    x1: f32,
    y1: f32,
) {
    let dy = y1 - y0;
    let dx = x1 - x0;
    let sy = (1f32).copysign(dy);
    let sx = (1f32).copysign(dx);
    let mut y = y0.floor();
    let mut x = x0.floor();
    if dy >= 0.0 {
        y += 1.0
    }
    if dx >= 0.0 {
        x += 1.0
    }
    let tdy = 1.0 / dy;
    let tdx = if dx == 0.0 {
        1048576.0
    } else {
        1.0 / dx
    };
    let mut tmy = tdy * (y - y0);
    let mut tmx = tdx * (x - x0);
    let tdy = tdy.abs();
    let tdx = tdx.abs();

    let mut x_prev = x0;
    let mut y_prev = y0;
    let mut x_next: f32;
    let mut y_next: f32;

    while tmx < 1.0 || tmy < 1.0 {
        if tmx < tmy {
            y_next = tmx * dy + y0;
            x_next = x;
            tmx += tdx;
            x += sx;
        } else {
            y_next = y;
            x_next = tmy * dx + x0;
            tmy += tdy;
            y += sy;
        }
        let coverage = Raster::coverage(x_prev, y_prev, x_next, y_next);
        self.add(x_prev + x_next, y_prev + y_next, coverage);
        x_prev = x_next;
        y_prev = y_next;
    }
    let coverage = Raster::coverage(x_prev, y_prev, x1, y1);
    self.add(x_prev + x1, y_prev + y1, coverage);
}