eoc2: update with initial values from the book.

rtchallenge/examples/eoc2.rs

@@ -35,14 +35,12 @@ fn draw_dot(c: &mut Canvas, x: usize, y: usize) {
     c.set(x + 1, y + 1, red);
 }
 fn main() -> Result<()> {
-    let mut p = Projectile {
-        position: point(0., 1., 0.),
-        velocity: 10. * vector(1., 2., 0.).normalize(),
-    };
-    let e = Environment {
-        gravity: vector(0., -0.1, 0.),
-        wind: vector(-0.01, 0., 0.),
-    };
+    let position = point(0., 1., 0.);
+    let velocity = vector(1., 1.8, 0.).normalize() * 11.25;
+    let mut p = Projectile { position, velocity };
+    let gravity = vector(0., -0.1, 0.);
+    let wind = vector(-0.01, 0., 0.);
+    let e = Environment { gravity, wind };
 
     let w = 800;
     let h = 600;