Start an `angle` module in `pathfinder_geometry`

geometry/src/angle.rs

@@ -0,0 +1,19 @@
+// pathfinder/geometry/src/angle.rs
+//
+// Copyright © 2020 The Pathfinder Project Developers.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Angle utilities.
+
+use std::f32::consts::PI;
+
+#[inline]
+pub fn angle_from_degrees(degrees: f32) -> f32 {
+    const SCALE: f32 = 2.0 * PI / 360.0;
+    degrees * SCALE
+}

geometry/src/lib.rs

@@ -10,6 +10,7 @@
 
 //! Basic geometry and linear algebra primitives, optimized with SIMD.
 
+pub mod angle;
 pub mod line_segment;
 pub mod rect;
 pub mod transform2d;