From 8c81561f9eb2922e16e4ce2b81a2b25b2e51ac0f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Manuel=20Tom=C3=A1s?= <jtomas1815@gmail.com>
Date: Sat, 30 Jan 2021 20:22:50 -0300
Subject: Remove intermediate Lerp object

Now polynomials can be created directly from bezier components.
---
 src/lerp.rs | 87 -------------------------------------------------------------
 src/lib.rs  | 33 ++++++++++++++++++-----
 2 files changed, 27 insertions(+), 93 deletions(-)
 delete mode 100644 src/lerp.rs

diff --git a/src/lerp.rs b/src/lerp.rs
deleted file mode 100644
index b5b771d..0000000
--- a/src/lerp.rs
+++ /dev/null
@@ -1,87 +0,0 @@
-use crate::poly::Poly;
-use std::rc::Rc;
-
-#[derive(PartialEq, Debug)]
-pub enum Lerp {
-    Node(Rc<Lerp>, Rc<Lerp>),
-    Leaf(f32, f32),
-    Just(f32),
-}
-
-impl Lerp {
-    pub fn new(v: &Vec<f32>) -> Rc<Lerp> {
-        match v.len() {
-            0 => Rc::new(Lerp::Just(0.0)),
-            1 => Rc::new(Lerp::Just(v[0])),
-            2 => Rc::new(Lerp::Leaf(v[0], v[1])),
-            _ => {
-                let mut lv = Vec::new();
-                for i in 0..v.len() - 1 {
-                    lv.push(Rc::new(Lerp::Leaf(v[i], v[i + 1])));
-                }
-                while lv.len() > 1 {
-                    let mut nlv = Vec::new();
-                    for i in 0..lv.len() - 1 {
-                        nlv.push(Rc::new(Lerp::Node(lv[i].clone(), lv[i + 1].clone())));
-                    }
-                    lv = nlv;
-                }
-                lv[0].clone()
-            }
-        }
-    }
-
-    pub fn to_poly(&self) -> Poly {
-        match self {
-            Lerp::Just(a) => Poly::new(vec![*a]),
-            Lerp::Leaf(a, b) => Poly::new(vec![*a, *b - *a]),
-            Lerp::Node(a, b) => {
-                let a = a.to_poly();
-                let b = b.to_poly();
-                let c = &b - &a;
-                &a + &c.shift()
-            }
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn new2_test() {
-        let a = Lerp::new(&vec![1.0, 2.0]);
-        assert_eq!(a, Rc::new(Lerp::Leaf(1.0, 2.0)));
-    }
-
-    #[test]
-    fn new3_test() {
-        let a = Lerp::new(&vec![1.0, 2.0, 3.0]);
-        assert_eq!(
-            a,
-            Rc::new(Lerp::Node(
-                Rc::new(Lerp::Leaf(1.0, 2.0)),
-                Rc::new(Lerp::Leaf(2.0, 3.0))
-            ))
-        );
-    }
-
-    #[test]
-    fn new4_test() {
-        let a = Lerp::new(&vec![1.0, 2.0, 3.0, 4.0]);
-        assert_eq!(
-            a,
-            Rc::new(Lerp::Node(
-                Rc::new(Lerp::Node(
-                    Rc::new(Lerp::Leaf(1.0, 2.0)),
-                    Rc::new(Lerp::Leaf(2.0, 3.0))
-                )),
-                Rc::new(Lerp::Node(
-                    Rc::new(Lerp::Leaf(2.0, 3.0)),
-                    Rc::new(Lerp::Leaf(3.0, 4.0))
-                ))
-            ))
-        );
-    }
-}
diff --git a/src/lib.rs b/src/lib.rs
index db5d42f..218d5b4 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,7 +1,5 @@
-mod lerp;
 mod poly;
 
-use lerp::Lerp;
 use poly::Poly;
 
 use std::ffi::{CStr, CString};
@@ -18,6 +16,29 @@ pub struct Bezier {
     pub dpy: Poly,
 }
 
+pub fn to_poly(v: &Vec<f32>) -> Poly {
+    match v.len() {
+        0 => Poly::new(vec![0.0]),
+        1 => Poly::new(vec![v[0]]),
+        2 => Poly::new(vec![v[0], v[1] - v[0]]),
+        _ => {
+            let mut pv = Vec::new();
+            for i in 0..v.len() - 1 {
+                pv.push(Poly::new(vec![v[i], v[i + 1] - v[i]]));
+            }
+            while pv.len() > 1 {
+                let mut npv = Vec::new();
+                for i in 0..pv.len() - 1 {
+                    let c = &pv[i + 1] - &pv[i];
+                    npv.push(&pv[i] + &c.shift());
+                }
+                pv = npv;
+            }
+            pv[0].clone()
+        }
+    }
+}
+
 impl Bezier {
     pub fn new() -> Bezier {
         Bezier {
@@ -34,8 +55,8 @@ impl Bezier {
     pub fn push(&mut self, x: i32, y: i32) {
         self.vx.push(x as f32);
         self.vy.push(y as f32);
-        self.px = Lerp::new(&self.vx).to_poly();
-        self.py = Lerp::new(&self.vy).to_poly();
+        self.px = to_poly(&self.vx);
+        self.py = to_poly(&self.vy);
         self.dpx = self.px.deriv();
         self.dpy = self.py.deriv();
         self.degree += 1;
@@ -44,8 +65,8 @@ impl Bezier {
     pub fn remove(&mut self, index: usize) {
         self.vx.remove(index);
         self.vy.remove(index);
-        self.px = Lerp::new(&self.vx).to_poly();
-        self.py = Lerp::new(&self.vy).to_poly();
+        self.px = to_poly(&self.vx);
+        self.py = to_poly(&self.vy);
         self.dpx = self.px.deriv();
         self.dpy = self.py.deriv();
         self.degree -= 1;
-- 
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