From b7ec69dc7f5ce23f2874260a69024d92b0f3b1a7 Mon Sep 17 00:00:00 2001
From: Robert Garrett <robertgarrett404@gmail.com>
Date: Tue, 6 Jun 2023 18:37:26 -0500
Subject: [PATCH] Feat: Camera positioning

The camera can now be fully described in 3D space. Close of Chapter 11.
---
 src/camera.rs | 25 ++++++++++++----------
 src/main.rs   | 58 +++++++++++++++++++++++++++++++++++++++++----------
 2 files changed, 61 insertions(+), 22 deletions(-)

diff --git a/src/camera.rs b/src/camera.rs
index 376e432..a7ed241 100644
--- a/src/camera.rs
+++ b/src/camera.rs
@@ -22,31 +22,34 @@ pub struct Camera {
 }
 
 impl Camera {
-    pub fn new(vfov: f32, aspect_ratio: f32) -> Camera {
+    pub fn new(lookfrom: Vec3, lookat: Vec3, vup: Vec3, vfov: f32, aspect_ratio: f32) -> Camera {
         let theta = degrees_to_radians(vfov);
         let h = (theta / 2.0).tan();
         let vp_height = 2.0 * h;
         let vp_width = aspect_ratio * vp_height;
 
-        let focal_length = 1.0;
+        let w = Vec3::as_unit(lookfrom - lookat);
+        let u = Vec3::as_unit(Vec3::cross(vup, w));
+        let v = Vec3::cross(w, u);
 
-        let horiz = Vec3::new(vp_width, 0.0, 0.0);
-        let verti = Vec3::new(0.0, vp_height, 0.0);
-        let orig = Vec3::zero();
+        let orig = lookfrom;
+        let horiz = u * vp_width;
+        let verti = v * vp_height;
+        let lower_left_corner = orig - horiz / 2.0 - verti / 2.0 - w;
 
         Camera{
             origin: orig,
-            lower_left_corner: orig - horiz/2.0 - verti/2.0 - Vec3::new(0.0, 0.0, focal_length),
+            lower_left_corner,
             horizontal: horiz,
             vertical: verti,
         }
     }
 
-    pub fn get_ray(&self, u: f32, v: f32) -> Ray {
-        let dir =   self.lower_left_corner
-                    + self.horizontal * u
-                    + self.vertical * v 
-                    - self.origin;
+    pub fn get_ray(&self, s: f32, t: f32) -> Ray {
+        let dir = self.lower_left_corner
+                + self.horizontal * s
+                + self.vertical * t 
+                - self.origin;
         Ray{
             orig: self.origin,
             dir,
diff --git a/src/main.rs b/src/main.rs
index 2b8db30..222162a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -32,18 +32,38 @@ fn main() {
     let max_depth = 50;
     
     // world
-
-    let R = std::f32::consts::FRAC_PI_4.cos();
-
-    let mat_left   = Material::Lambertian { albedo: Vec3::new(0.0, 0.0, 1.0) };
-    let mat_right  = Material::Lambertian { albedo: Vec3::new(1.0, 0.0, 0.0) };
+    
+    let mat_ground = Material::Lambertian { albedo: Vec3::new(0.8, 0.8, 0.0) };
+    let mat_center = Material::Lambertian { albedo: Vec3::new(0.1, 0.2, 0.5) };
+    let mat_left   = Material::Dielectric { index_refraction: 1.5 }; 
+    let mat_right  = Material::Metal { albedo: Vec3::new(0.8, 0.6, 0.2), fuzz: 0.0 };
 
     let mut world = HittableList::new();
     world.add(
         Box::new(
             Sphere {
-                center: Vec3::new( -R, 0.0, -1.0),
-                radius: R,
+                center: Vec3::new(0.0, -100.5, -1.0),
+                radius: 100.0,
+                material: Some(mat_ground),
+            }
+        )
+    );
+
+    world.add(
+        Box::new(
+            Sphere {
+                center: Vec3::new(0.0, 0.0, -1.0),
+                radius: 0.5,
+                material: Some(mat_center),
+            }
+        )
+    );
+
+    world.add(
+        Box::new(
+            Sphere {
+                center: Vec3::new(-1.0, 0.0, -1.0),
+                radius: 0.5,
                 material: Some(mat_left),
             }
         )
@@ -52,17 +72,33 @@ fn main() {
     world.add(
         Box::new(
             Sphere {
-                center: Vec3::new( R, 0.0, -1.0),
-                radius: R,
+                center: Vec3::new(-1.0, 0.0, -1.0),
+                radius: -0.45,
+                material: Some(mat_left),
+            }
+        )
+    );
+
+    world.add(
+        Box::new(
+            Sphere {
+                center: Vec3::new(1.0, 0.0, -1.0),
+                radius: 0.5,
                 material: Some(mat_right),
             }
         )
     );
 
-    
+
     // camera
 
-    let cam = Camera::new(90.0, aspect_ratio);
+    let cam = Camera::new(
+        Vec3::new(-2.0, 2.0, 1.0),
+        Vec3::new(0.0, 0.0, -1.0),
+        Vec3::new(0.0, 1.0, 0.0),
+        20.0,
+        aspect_ratio
+    );
 
     // render
     let mut small_rng = SmallRng::from_entropy();