Add Vec4::xyz()

src/math/vec4.rs

@@ -1,4 +1,4 @@
-use super::Float;
+use super::{Float, Vec3};
 
 use itertools::izip;
 
@@ -32,6 +32,12 @@ impl<T: Float> Vec4<T> {
         self.coords[3]
     }
 
+    pub fn xyz(&self) -> Vec3<T> {
+        let mut coords = [T::zero(); 3];
+        coords.copy_from_slice(&self.coords[0..3]);
+        Vec3 { coords }
+    }
+
     pub fn dot(&self, rhs: &Vec4<T>) -> T {
         self.coords
             .iter()
@@ -138,6 +144,14 @@ mod tests {
         assert!(target.w() == 4.0);
     }
 
+    #[test]
+    fn xyz_returns_expected_value() {
+        let target = Vec4::new(1.0, 2.0, 3.0, 4.0).xyz();
+        assert!(target.x() == 1.0);
+        assert!(target.y() == 2.0);
+        assert!(target.z() == 3.0);
+    }
+
     #[test]
     fn dot_product_returns_correct_result() {
         let a = Vec4::new(1.0, 2.0, 3.0, 4.0);