From 21ac03acfb1a62538655fdd81f8850b872535e0e Mon Sep 17 00:00:00 2001
From: Bill Thiede <git@xinu.tv>
Date: Thu, 24 Jun 2021 15:35:58 -0700
Subject: [PATCH] Implement end of chapter 1 exercises.

---
 rtchallenge/examples/eoc1.rs | 39 ++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 rtchallenge/examples/eoc1.rs

diff --git a/rtchallenge/examples/eoc1.rs b/rtchallenge/examples/eoc1.rs
new file mode 100644
index 0000000..c8f0110
--- /dev/null
+++ b/rtchallenge/examples/eoc1.rs
@@ -0,0 +1,39 @@
+use rtchallenge::tuples::{point, vector, Tuple};
+
+#[derive(Debug)]
+struct Environment {
+    gravity: Tuple,
+    wind: Tuple,
+}
+#[derive(Debug)]
+struct Projectile {
+    position: Tuple,
+    velocity: Tuple,
+}
+
+fn tick(env: &Environment, proj: &Projectile) -> Projectile {
+    let position = proj.position + proj.velocity;
+    let velocity = proj.velocity + env.gravity + env.wind;
+    Projectile { position, velocity }
+}
+fn main() {
+    let mut p = Projectile {
+        position: point(0., 1., 0.),
+        velocity: 4. * vector(1., 1., 0.).normalize(),
+    };
+    let e = Environment {
+        gravity: vector(0., -0.1, 0.).normalize(),
+        wind: vector(-0.01, 0., 0.),
+    };
+
+    let mut i = 0;
+    while p.position.y > 0. {
+        p = tick(&e, &p);
+        println!("tick {}: position {:?}", i, p.position);
+        i += 1;
+        if i > 100 {
+            eprintln!("too many iterations");
+            return;
+        }
+    }
+}