feature(polygon-math::Vector2): add Vector2 type and other utilities

- Add Vector2 type to polygon-math.
-

lib/polygon_math/src/lib.rs

@@ -11,8 +11,8 @@ pub mod quaternion;
 mod test;
 
 pub use self::point::Point;
-pub use self::vector::Vector3;
-pub use self::matrix::{Matrix4, Matrix3};
+pub use self::vector::{Vector2, Vector3};
+pub use self::matrix::{Matrix3, Matrix4};
 pub use self::color::Color;
 pub use self::quaternion::Quaternion;
 

lib/polygon_math/src/point.rs

@@ -91,6 +91,16 @@ impl Point {
             slice::from_raw_parts(data, len * 4)
         }
     }
+
+    pub fn slice_as_f32_slice(raw: &[f32]) -> &[Point] {
+        assert!(raw.len() % 4 == 0, "To convert a slice of f32 to a slice of Point it must have a length that is a multiple of 4");
+
+        unsafe {
+            slice::from_raw_parts(
+                raw.as_ptr() as *const Point,
+                raw.len() / 4)
+        }
+    }
 }
 
 impl Sub for Point {

lib/polygon_math/src/vector.rs

@@ -99,6 +99,16 @@ impl Vector3 {
         self.x * self.x + self.y * self.y + self.z * self.z
     }
 
+    // Safely reinterprets a slice of Vector3s to a slice of f32s. This is a cheap operation and
+    // does not copy any data.
+    pub fn as_ref(vectors: &[Vector3]) -> &[f32] {
+        unsafe {
+            ::std::slice::from_raw_parts(
+                vectors.as_ptr() as *const f32,
+                vectors.len() * 3)
+        }
+    }
+
     // pub fn cross(&self, rhs: Vector3) -> Vector3 {
     //     Vector3::new(
     //         self.y * rhs.z - self.z * rhs.y,
@@ -280,3 +290,18 @@ impl IndexMut<usize> for Vector3 {
         }
     }
 }
+
+#[derive(Debug, Copy, Clone, PartialEq, PartialOrd)]
+pub struct Vector2 {
+    pub x: f32,
+    pub y: f32,
+}
+
+impl Vector2 {
+    pub fn new(x: f32, y: f32) -> Vector2 {
+        Vector2 {
+            x: x,
+            y: y,
+        }
+    }
+}