From 9724f0d0fe318615e4ed79b1600dd4557a2378eb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Manuel=20Tom=C3=A1s?= <jtomas1815@gmail.com>
Date: Thu, 7 Jan 2021 20:14:15 -0300
Subject: Visualize polynomials using sdl

---
 src/main.rs | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 61 insertions(+), 3 deletions(-)

(limited to 'src/main.rs')

diff --git a/src/main.rs b/src/main.rs
index 1e4f704..13f13da 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,63 @@
+use poly::Poly;
+use poly::Number;
+use poly::Lerp;
+
+use sdl2::pixels::Color;
+use sdl2::event::Event;
+use sdl2::keyboard::Keycode;
+use sdl2::rect::Rect;
+
+use std::thread;
+use std::time::Duration;
+
+fn eval_poly(p: &Poly, t: Number) -> Number {
+    let mut r = 0.0;
+    for i in 0..p.len() {
+        r += p[i] * t.powi(i as i32);
+    }
+    r
+}
+
 fn main() {
-    let a = poly::Lerp::new(vec![1.0, 5.0, 8.0, 3.0, 10.0]);
-    println!("{:?}", a);
-    println!("{:?}", poly::lp(a));
+    let a = Lerp::new(vec![100.0, 200.0, 300.0, 500.0]);
+    let b = Lerp::new(vec![400.0, 140.0, 500.0, 300.0]);
+    let pa = poly::lp(a);
+    let pb = poly::lp(b);
+
+    let sdl_context = sdl2::init().unwrap();
+    let video_subsystem = sdl_context.video().unwrap();
+
+    let window = video_subsystem.window("rust-sdl2 demo", 800, 600)
+        .position_centered()
+        .build()
+        .unwrap();
+
+    let mut canvas = window.into_canvas().build().unwrap();
+
+    let mut event_pump = sdl_context.event_pump().unwrap();
+    'running: loop {
+        canvas.set_draw_color(Color::RGB(20, 20, 20));
+        canvas.clear();
+        for event in event_pump.poll_iter() {
+            match event {
+                Event::Quit {..} |
+                    Event::KeyDown { keycode: Some(Keycode::Escape), .. } => {
+                        break 'running
+                    },
+                _ => {}
+            }
+        }
+
+        for t in 0..800 {
+            let x = eval_poly(&pa, t as Number / 800.0);
+            let y = eval_poly(&pb, t as Number / 800.0);
+            canvas.set_draw_color(Color::RGB(180, 20, 20));
+            canvas.fill_rect(Rect::new(t, x as i32, 5, 5)).unwrap();
+            canvas.set_draw_color(Color::RGB(20, 180, 20));
+            canvas.fill_rect(Rect::new(t, y as i32, 5, 5)).unwrap();
+        }
+
+        canvas.present();
+        thread::sleep(Duration::new(0, 1_000_000_000u32 / 60));
+    }
 }
-- 
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