From 259505e93f88a7a013ba26ef6ac468f0cda8e26c Mon Sep 17 00:00:00 2001
From: Matthew Gordon <matthew.scott.gordon@gmail.com>
Date: Thu, 6 Feb 2020 17:36:36 -0500
Subject: [PATCH] Add RealFieldNormalizer

---
 src/util/mod.rs        |  4 +-
 src/util/normalizer.rs | 97 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 99 insertions(+), 2 deletions(-)
 create mode 100644 src/util/normalizer.rs

diff --git a/src/util/mod.rs b/src/util/mod.rs
index a260f84..d3e5cf6 100644
--- a/src/util/mod.rs
+++ b/src/util/mod.rs
@@ -1,5 +1,5 @@
 mod interval;
+pub use interval::Interval;
 
 pub mod axis_aligned_bounding_box;
-
-pub use interval::Interval;
+pub mod normalizer;
diff --git a/src/util/normalizer.rs b/src/util/normalizer.rs
new file mode 100644
index 0000000..550745e
--- /dev/null
+++ b/src/util/normalizer.rs
@@ -0,0 +1,97 @@
+use super::Interval;
+
+use nalgebra::{clamp, RealField};
+
+pub struct RealFieldNormalizer<T: RealField> {
+    min: T,
+    range: T,
+}
+
+impl<T: RealField> RealFieldNormalizer<T> {
+    pub fn new(interval: Interval<T>) -> Self {
+        let min = interval.get_min();
+        let range = interval.get_max() - min;
+        Self { min, range }
+    }
+
+    pub fn normalize(&self, value: T) -> T {
+        (value - self.min) / self.range
+    }
+
+    pub fn normalize_and_clamp(&self, value: T) -> T {
+        clamp((value - self.min) / self.range, T::zero(), T::one())
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    use quickcheck_macros::quickcheck;
+
+    #[quickcheck]
+    fn normalize_zero_to_one_yields_input(value: f64) -> bool {
+        let target = RealFieldNormalizer::new(Interval::new(0.0, 1.0));
+        target.normalize(value) == value
+    }
+
+    #[quickcheck]
+    fn normalize_two_to_three_yields_input_minus_two(value: f64) -> bool {
+        let target = RealFieldNormalizer::new(Interval::new(2.0, 3.0));
+        target.normalize(value) == value - 2.0
+    }
+
+    #[quickcheck]
+    fn normalize_negative_three_to_negative_two_yields_input_plus_three(value: f64) -> bool {
+        let target = RealFieldNormalizer::new(Interval::new(-3.0, -2.0));
+        target.normalize(value) == value + 3.0
+    }
+
+    #[quickcheck]
+    fn normalize_zero_to_two_yields_input_divided_by_two(value: f64) -> bool {
+        let target = RealFieldNormalizer::new(Interval::new(0.0, 2.0));
+        target.normalize(value) == value / 2.0
+    }
+
+    #[test]
+    fn normalize_two_to_four_yields_zero_when_input_is_two() {
+        let target = RealFieldNormalizer::new(Interval::new(2.0, 4.0));
+        assert!(target.normalize(2.0) == 0.0)
+    }
+
+    #[test]
+    fn normalize_two_to_four_yields_one_when_input_is_four() {
+        let target = RealFieldNormalizer::new(Interval::new(2.0, 4.0));
+        assert!(target.normalize(4.0) == 1.0)
+    }
+
+    #[quickcheck]
+    fn normalize_two_to_four_yields_input_divided_by_two_minus_one(value: f64) -> bool {
+        let target = RealFieldNormalizer::new(Interval::new(2.0, 4.0));
+        target.normalize(value) == (value - 2.0) / 2.0
+    }
+
+    #[quickcheck]
+    fn normalize_and_clamp_two_to_four_yields_zero_when_input_less_than_or_equal_two(
+        value: f64,
+    ) -> bool {
+        let target = RealFieldNormalizer::new(Interval::new(2.0, 4.0));
+        target.normalize_and_clamp(value) == 0.0 || value > 2.0
+    }
+
+    #[quickcheck]
+    fn normalize_and_clamp_two_to_four_yields_one_when_input_greater_than_or_equal_four(
+        value: f64,
+    ) -> bool {
+        let target = RealFieldNormalizer::new(Interval::new(2.0, 4.0));
+        target.normalize_and_clamp(value) == 1.0 || value < 4.0
+    }
+
+    #[quickcheck]
+    fn normalize_and_clamp_two_to_four_yields_same_value_as_normalize_when_in_range(
+        value: f64,
+    ) -> bool {
+        let target = RealFieldNormalizer::new(Interval::new(2.0, 4.0));
+        target.normalize_and_clamp(value) == target.normalize(value) || value < 2.0 || value > 4.0
+    }
+}