X-Git-Url: http://www.dolda2000.com/gitweb/?a=blobdiff_plain;f=src%2Fcommon%2Fgeometry.rs;h=455e600040998e685d04fbd1962a81807195fcf9;hb=60058b918569190f437fe996dfc79daf5a431b91;hp=5a03ffb79da30bf2b36007fe0c920bf88989bd18;hpb=1f42d724d84ed1c014ff40ccc91058472391be0c;p=kaka%2Frust-sdl-test.git

diff --git a/src/common/geometry.rs b/src/common/geometry.rs
index 5a03ffb..455e600 100644
--- a/src/common/geometry.rs
+++ b/src/common/geometry.rs
@@ -1,5 +1,7 @@
 use std::ops::{Add, AddAssign, Sub, SubAssign, Mul, MulAssign, Div, DivAssign, Neg};
 
+////////// POINT ///////////////////////////////////////////////////////////////
+
 #[macro_export]
 macro_rules! point {
     ( $x:expr, $y:expr ) => {
@@ -181,6 +183,36 @@ impl Radians {
     }
 }
 
+////////// INTERSECTION ////////////////////////////////////////////////////////
+
+#[derive(Debug)]
+pub enum Intersection {
+    Point(Point<f64>),
+    //Line(Point<f64>, Point<f64>), // TODO: overlapping collinear
+    None,
+}
+
+impl Intersection {
+    pub fn lines(p1: Point<f64>, p2: Point<f64>, p3: Point<f64>, p4: Point<f64>) -> Intersection {
+	let s1 = p2 - p1;
+	let s2 = p4 - p3;
+
+	let denomimator = -s2.x * s1.y + s1.x * s2.y;
+	if denomimator != 0.0 {
+	    let s = (-s1.y * (p1.x - p3.x) + s1.x * (p1.y - p3.y)) / denomimator;
+	    let t = ( s2.x * (p1.y - p3.y) - s2.y * (p1.x - p3.x)) / denomimator;
+
+	    if s >= 0.0 && s <= 1.0 && t >= 0.0 && t <= 1.0 {
+		return Intersection::Point(p1 + (s1 * t))
+	    }
+	}
+
+	Intersection::None
+    }
+}
+
+////////// DIMENSION ///////////////////////////////////////////////////////////
+
 #[macro_export]
 macro_rules! dimen {
     ( $w:expr, $h:expr ) => {
@@ -210,16 +242,7 @@ impl<T> From<(T, T)> for Dimension<T> {
     }
 }
 
-#[macro_export]
-macro_rules! hashmap {
-    ($($k:expr => $v:expr),*) => {
-	{
-	    let mut map = std::collections::HashMap::new();
-	    $(map.insert($k, $v);)*
-	    map
-	}
-    }
-}
+////////// TESTS ///////////////////////////////////////////////////////////////
 
 #[cfg(test)]
 mod tests {
@@ -296,4 +319,18 @@ mod tests {
         assert_eq!(r.area(), 30 * 20);
         // let a = Dimension::from(("a".to_string(), "b".to_string())).area(); // this doesn't work, because area() is not implemented for String
     }
+
+    #[test]
+    fn intersection_of_lines() {
+        let p1 = point!(0.0, 0.0);
+        let p2 = point!(2.0, 2.0);
+        let p3 = point!(0.0, 2.0);
+        let p4 = point!(2.0, 0.0);
+	let r = Intersection::lines(p1, p2, p3, p4);
+	if let Intersection::Point(p) = r {
+            assert_eq!(p, point!(1.0, 1.0));
+	} else {
+	    panic!();
+	}
+    }
 }