115 lines
2.7 KiB
Rust
115 lines
2.7 KiB
Rust
mod common;
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use ccvl::filter::*;
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use ccvl::hough;
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use ccvl::image::*;
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const LINE: SRGBA = SRGBA {
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r: 1.0,
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g: 0.0,
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b: 0.0,
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a: 1.0,
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};
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fn main() -> std::process::ExitCode {
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common::process_image(|mut img| {
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let greyscale = img.map(|p| Luminance::from(p));
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let edges = canny(greyscale);
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for line in hough::lines(10.0, edges) {
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draw(line, &mut img);
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}
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img
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})
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}
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fn in_bounds(q: &(f32, f32), lim: Extent) -> bool {
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let x_in = 0.0 <= q.0 && q.0 < lim.x as f32;
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let y_in = 0.0 <= q.1 && q.1 < lim.y as f32;
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x_in && y_in
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}
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fn endpoints(
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l: hough::Line,
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lim: Extent,
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) -> ((usize, usize), (usize, usize)) {
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let w = lim.x as f32 - 1e-3;
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let h = lim.y as f32 - 1e-3;
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let ros = l.rho / l.theta.sin();
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let roc = l.rho / l.theta.cos();
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let t = l.theta.tan();
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let candidates: [(f32, f32); 4] =
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[(roc - h * t, h), (0.0, ros), (roc, 0.0), (w, ros - w / t)];
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let res = candidates
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.into_iter()
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.filter(|p| in_bounds(p, lim))
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.map(|(x, y)| (x as usize, y as usize))
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.collect::<Vec<_>>();
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if res.len() != 2 {
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panic!("Unexpected number of endpoints for {:?}", l);
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}
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(res[0], res[1])
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}
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fn draw(l: hough::Line, img: &mut Image<SRGBA>) {
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if l.theta.abs() < 1e-3 {
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// vertical line
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let x = l.rho as usize;
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for y in 0..img.extent.y {
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if x >= img.extent.x || y >= img.extent.y {
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return;
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}
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*img.at_mut(x, y) = LINE;
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}
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} else if (l.theta - std::f32::consts::PI / 2.0) < 1e-3 {
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// horizontal line
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let y = l.rho as usize;
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for x in 0..img.extent.x {
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if x >= img.extent.x || y >= img.extent.y {
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return;
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}
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*img.at_mut(x, y) = LINE;
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}
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} else {
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bresenham(endpoints(l, img.extent), img);
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}
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}
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fn bresenham(qs: ((usize, usize), (usize, usize)), img: &mut Image<SRGBA>) {
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let ((x0, y0), (x1, y1)) = qs;
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let dx = x0.abs_diff(x1) as isize;
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let dy = -(y0.abs_diff(y1) as isize);
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let sx = if x0 < x1 { 1 } else { -1 };
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let sy = if y0 < y1 { 1 } else { -1 };
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let mut x = x0;
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let mut y = y0;
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let mut error = dx + dy;
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loop {
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if x >= img.extent.x || y >= img.extent.y {
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return;
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}
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*img.at_mut(x, y) = LINE;
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let e2 = 2 * error;
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if e2 >= dy {
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if x == x1 {
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break;
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}
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error += dy;
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x = (x as isize + sx) as usize;
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}
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if e2 <= dx {
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if y == y1 {
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break;
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}
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error += dx;
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y = (y as isize + sy) as usize;
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}
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}
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}
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