From cc0a9580ab4602da7c186cbd6590fb7e45a113f6 Mon Sep 17 00:00:00 2001
From: Dimitri Sabadie <dimitri.sabadie@gmail.com>
Date: Thu, 17 Oct 2019 15:31:05 +0200
Subject: [PATCH] Add Interpolation::StrokeBezier.

---
 .github/workflows/ci.yaml |  6 +++++-
 CHANGELOG.md              | 12 ++++++++++++
 Cargo.toml                |  2 +-
 src/interpolation.rs      | 12 ++++++++++++
 src/spline.rs             |  9 ++++++++-
 5 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 43b7110..e080a33 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -26,14 +26,18 @@ jobs:
           cargo test --verbose --all-features
 
   build-macosx:
-    runs-on: macosx-latest
+    runs-on: macOS-latest
     steps:
       - uses: actions/checkout@v1
+      - name: Rust requirements
+        run: curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile=minimal
       - name: Build
         run: |
+          . ~/.cargo/env
           cargo build --verbose --all-features
       - name: Test
         run: |
+          . ~/.cargo/env
           cargo test --verbose --all-features
 
   check-readme:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6ba7647..358802f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,15 @@
+# 2.2.0
+
+> Mon Oct 17th 2019
+
+- Add `Interpolation::StrokeBezier`.
+
+# 2.1.1
+
+> Mon Oct 17th 2019
+
+- Licensing support in the crate.
+
 # 2.1
 
 > Mon Sep 30th 2019
diff --git a/Cargo.toml b/Cargo.toml
index c6f4366..471fbea 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "splines"
-version = "2.1.1"
+version = "2.2.0"
 license = "BSD-3-Clause"
 authors = ["Dimitri Sabadie <dimitri.sabadie@gmail.com>"]
 description = "Spline interpolation made easy"
diff --git a/src/interpolation.rs b/src/interpolation.rs
index 52a40cc..7d30586 100644
--- a/src/interpolation.rs
+++ b/src/interpolation.rs
@@ -40,6 +40,18 @@ pub enum Interpolation<T, V> {
   ///   point and the current control point’s associated point. This is called _quadratic Bézer
   ///   interpolation_ and it kicks ass too, but a bit less than cubic.
   Bezier(V),
+  /// A special Bézier interpolation using an _input tangent_ and an _output tangent_.
+  ///
+  /// With this kind of interpolation, a control point has an input tangent, which has the same role
+  /// as the one defined by [`Interpolation::Bezier`], and an output tangent, which has the same
+  /// role defined by the next key’s [`Interpolation::Bezier`] if present, normally.
+  ///
+  /// What it means is that instead of setting the output tangent as the next key’s Bézier tangent,
+  /// this interpolation mode allows you to manually set the output tangent. That will yield more
+  /// control on the tangents but might generate discontinuities. Use with care.
+  ///
+  /// Stroke Bézier interpolation is always a cubic Bézier interpolation by default.
+  StrokeBezier(V, V),
   #[doc(hidden)]
   __NonExhaustive
 }
diff --git a/src/spline.rs b/src/spline.rs
index 819c4da..2051dea 100644
--- a/src/spline.rs
+++ b/src/spline.rs
@@ -84,7 +84,6 @@ impl<T, V> Spline<T, V> {
   /// sampling impossible. For instance, [`Interpolation::CatmullRom`] requires *four* keys. If
   /// you’re near the beginning of the spline or its end, ensure you have enough keys around to make
   /// the sampling.
-  ///
   pub fn sample_with_key(&self, t: T) -> Option<(V, &Key<T, V>, Option<&Key<T, V>>)>
   where T: Additive + One + Trigo + Mul<T, Output = T> + Div<T, Output = T> + PartialOrd,
         V: Interpolate<T> {
@@ -150,6 +149,14 @@ impl<T, V> Spline<T, V> {
         Some((value, cp0, Some(cp1)))
       }
 
+      Interpolation::StrokeBezier(input, output) => {
+        let cp1 = &keys[i + 1];
+        let nt = normalize_time(t, cp0, cp1);
+        let value = Interpolate::cubic_bezier(cp0.value, input, output, cp1.value, nt);
+
+        Some((value, cp0, Some(cp1)))
+      }
+
       Interpolation::__NonExhaustive => unreachable!(),
     }
   }