Switch to the Robust crate for predicate checks

urschrei · Aug 21, 2020 · 0c3c191 · 0c3c191
1 parent f6a5b0a
commit 0c3c191
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Showing 2 changed files with 16 additions and 2 deletions.
diff --git a/geo-types/Cargo.toml b/geo-types/Cargo.toml
@@ -15,6 +15,7 @@ approx = "0.3"
 num-traits = "0.2"
 serde = { version = "1", optional = true, features = ["derive"] }
 rstar = { version = "0.8", optional = true }
+robust = "0.2.2"
 
 [dev-dependencies]
 approx = "0.3"
diff --git a/geo-types/src/point.rs b/geo-types/src/point.rs
@@ -1,5 +1,7 @@
 use crate::{Coordinate, CoordinateType};
+use num_traits::NumCast;
 use num_traits::Float;
+use robust::{orient2d, Coord};
 use std::ops::Add;
 use std::ops::Neg;
 use std::ops::Sub;
@@ -242,8 +244,19 @@ where
     /// assert_eq!(cross, 2.0)
     /// ```
     pub fn cross_prod(self, point_b: Point<T>, point_c: Point<T>) -> T {
-        (point_b.x() - self.x()) * (point_c.y() - self.y())
-            - (point_b.y() - self.y()) * (point_c.x() - self.x())
+        let pa: Coord<f64> = Coord {
+            x: NumCast::from(self.x()).unwrap(),
+            y: NumCast::from(self.y()).unwrap(),
+        };
+        let pb: Coord<f64> = Coord {
+            x: NumCast::from(point_b.x()).unwrap(),
+            y: NumCast::from(point_b.y()).unwrap(),
+        };
+        let pc: Coord<f64> = Coord {
+            x: NumCast::from(point_c.x()).unwrap(),
+            y: NumCast::from(point_c.y()).unwrap(),
+        };
+        T::from(orient2d(pa, pb, pc)).unwrap()
     }
 }