Minor changes for speed up

src/render.rs

@@ -122,9 +122,12 @@ impl Camera {
 	for t in  threads {
 	    for c in t {
 		let ((x,y),rgb) = c;
-		let px = self.img.get_pixel(x,y).unwrap();
+		if let Some(px) = self.img.get_pixel(x,y){
 		    let (r,g,b)= rgb;
 		    px.set_color(r,g,b);
+		} else {
+		    eprintln!("Invalid pixel: ({} {})",x,y);
+		}
 	    }
 	}
 	self.img.save("./foo.ppm").unwrap();

src/vec3.rs

@@ -1,5 +1,6 @@
 use std::ops::{Add, Div, Mul, Sub};
 
+#[repr(align(32))]
 #[derive(Clone, Copy)]
 pub struct Vec3 {
     x: f64,
@@ -7,6 +8,7 @@ pub struct Vec3 {
     z: f64,
 }
 
+#[repr(align(32))]
 #[derive(Clone, Copy)]
 pub struct Point3 {
     x: f64,
@@ -132,6 +134,7 @@ impl Vec3 {
             z: self.z,
         }
     }
+
     pub fn dot(self, other: Vec3) -> f64 {
         self.x * other.x + self.y * other.y + self.z * other.z
     }
@@ -149,10 +152,11 @@ impl Vec3 {
     }
 
     pub fn cross(self, other: Vec3) -> Vec3 {
-        let x = self.y * other.z - self.z * other.y;
-        let y = self.z * other.x - self.x * other.z;
-        let z = self.x * other.y - self.y * other.x;
-        Vec3 { x, y, z }
+	Vec3{
+            x: self.y * other.z - self.z * other.y,
+            y: self.z * other.x - self.x * other.z,
+            z: self.x * other.y - self.y * other.x,
+	}
     }
 
     pub fn length_squared(self) -> f64 {