# HG changeset patch
# User unc0rr
# Date 1539551867 -7200
# Node ID a83ba9ba1566c26b0b06217657fa2038a7ebc965
# Parent  cd437d76978afcb8ed7187c58f90b0f3fdc6f317
Start land2d library implementation: draw_line() method

diff -r cd437d76978a -r a83ba9ba1566 rust/land2d/Cargo.toml
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rust/land2d/Cargo.toml	Sun Oct 14 23:17:47 2018 +0200
@@ -0,0 +1,7 @@
+[package]
+name = "land2d"
+version = "0.1.0"
+authors = ["Andrey Korotaev <a.korotaev@hedgewars.org>"]
+
+[dependencies]
+vec2d = { path = "../vec2d" }
diff -r cd437d76978a -r a83ba9ba1566 rust/land2d/src/lib.rs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rust/land2d/src/lib.rs	Sun Oct 14 23:17:47 2018 +0200
@@ -0,0 +1,101 @@
+extern crate vec2d;
+
+use std::cmp;
+
+pub struct Land2D<T> {
+    pixels: vec2d::Vec2D<T>,
+    width_mask: usize,
+    height_mask: usize,
+}
+
+impl<T: Default + Copy> Land2D<T> {
+    pub fn new(width: usize, height: usize) -> Self {
+        assert!(width.is_power_of_two());
+        assert!(height.is_power_of_two());
+
+        Self {
+            pixels: vec2d::Vec2D::new(width, height, T::default()),
+            width_mask: !(width - 1),
+            height_mask: !(height - 1),
+        }
+    }
+
+    #[inline]
+    fn is_valid_coordinate(&self, x: i32, y: i32) -> bool {
+        (x as usize & self.width_mask) == 0 && (y as usize & self.height_mask) == 0
+    }
+
+    #[inline]
+    pub fn map<U, F: FnOnce(&mut T) -> U>(&mut self, y: i32, x: i32, f: F) {
+        if self.is_valid_coordinate(x, y) {
+            self.pixels.get_mut(y as usize, x as usize).map(f);
+        }
+    }
+
+    pub fn draw_line(&mut self, x1: i32, y1: i32, x2: i32, y2: i32, value: T) {
+        let mut e_x: i32 = 0;
+        let mut e_y: i32 = 0;
+        let mut d_x: i32 = x2 - x1;
+        let mut d_y: i32 = y2 - y1;
+
+        let s_x: i32;
+        let s_y: i32;
+
+        if d_x > 0 {
+            s_x = 1;
+        } else if d_x < 0 {
+            s_x = -1;
+            d_x = -d_x;
+        } else {
+            s_x = d_x;
+        }
+
+        if d_y > 0 {
+            s_y = 1;
+        } else if d_y < 0 {
+            s_y = -1;
+            d_y = -d_y;
+        } else {
+            s_y = d_y;
+        }
+
+        let d = cmp::max(d_x, d_y);
+
+        let mut x = x1;
+        let mut y = y1;
+
+        for _i in 0..=d {
+            e_x += d_x;
+            e_y += d_y;
+
+            if e_x > d {
+                e_x -= d;
+                x += s_x;
+            }
+            if e_y > d {
+                e_y -= d;
+                y += s_y;
+            }
+
+            self.map(y, x, |p| *p = value);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn basics() {
+        let  l:Land2D<u8> = Land2D::new(32, 64);
+
+        assert!(l.is_valid_coordinate(0, 0));
+        assert!(!l.is_valid_coordinate(-1, -1));
+
+        assert!(l.is_valid_coordinate(31, 63));
+        assert!(!l.is_valid_coordinate(32, 63));
+        assert!(!l.is_valid_coordinate(31, 64));
+    }
+
+}