rust/integral-geometry/src/lib.rs
author unc0rr
Wed, 17 Oct 2018 22:45:33 +0200
changeset 13956 75eaf7c71789
child 13958 7f1c178506bb
permissions -rw-r--r--
Introduce integral-geometry crate, implement LinePoints iterator
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use std::cmp;
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pub struct LinePoints {
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    e_x: i32,
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    e_y: i32,
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    d_x: i32,
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    d_y: i32,
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    s_x: i32,
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    s_y: i32,
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    x: i32,
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    y: i32,
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    d: i32,
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    i: i32,
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}
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impl LinePoints {
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    pub fn new(x1: i32, y1: i32, x2: i32, y2: i32) -> Self {
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        let mut d_x: i32 = x2 - x1;
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        let mut d_y: i32 = y2 - y1;
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        let s_x: i32;
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        let s_y: i32;
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        if d_x > 0 {
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            s_x = 1;
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        } else if d_x < 0 {
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            s_x = -1;
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            d_x = -d_x;
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        } else {
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            s_x = d_x;
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        }
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        if d_y > 0 {
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            s_y = 1;
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        } else if d_y < 0 {
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            s_y = -1;
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            d_y = -d_y;
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        } else {
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            s_y = d_y;
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        }
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        Self {
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            e_x: 0,
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            e_y: 0,
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            d_x,
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            d_y,
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            s_x,
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            s_y,
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            x: x1,
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            y: y1,
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            d: cmp::max(d_x, d_y),
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            i: 0,
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        }
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    }
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}
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impl Iterator for LinePoints {
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    type Item = (i32, i32);
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    fn next(&mut self) -> Option<Self::Item> {
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        if self.i <= self.d {
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            self.e_x += self.d_x;
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            self.e_y += self.d_y;
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            if self.e_x > self.d {
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                self.e_x -= self.d;
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                self.x += self.s_x;
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            }
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            if self.e_y > self.d {
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                self.e_y -= self.d;
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                self.y += self.s_y;
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            }
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            self.i += 1;
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            Some((self.x, self.y))
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        } else {
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            None
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        }
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    }
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}
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#[cfg(test)]
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mod tests {
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    use super::*;
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    #[test]
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    fn basic() {
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        let v = vec![(0, 0), (1, 1), (2, 2), (3, 3)];
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        for (&a, b) in v.iter().zip(LinePoints::new(0, 0, 3, 3)) {
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            assert_eq!(a, b);
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        }
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    }
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}