From b68462f1f76569db699d43eaa7923a0186ebfc0c Mon Sep 17 00:00:00 2001
From: Alan Jian <alanjian85@outlook.com>
Date: Wed, 17 Jul 2024 15:01:13 +0800
Subject: [PATCH] feat: add Camera struct

---
 src/camera.rs | 38 ++++++++++++++++++++++++++++++++++++++
 src/main.rs   | 19 +++++--------------
 2 files changed, 43 insertions(+), 14 deletions(-)
 create mode 100644 src/camera.rs

diff --git a/src/camera.rs b/src/camera.rs
new file mode 100644
index 0000000..fba21b4
--- /dev/null
+++ b/src/camera.rs
@@ -0,0 +1,38 @@
+use crate::Ray;
+use nalgebra::{Point2, Point3, Vector3};
+
+pub struct Camera {
+    pos: Point3<f64>,
+    pix_orig: Point3<f64>,
+    pix_delta_x: Vector3<f64>,
+    pix_delta_y: Vector3<f64>,
+}
+
+impl Camera {
+    pub fn new(pos: Point3<f64>, width: u32, height: u32, focal_len: f64) -> Self {
+        let aspect_ratio = width as f64 / height as f64;
+        let viewport_height = 2.0;
+        let viewport_width = viewport_height * aspect_ratio;
+
+        let pix_delta_x = Vector3::new(viewport_width, 0.0, 0.0) / width as f64;
+        let pix_delta_y = Vector3::new(0.0, -viewport_height, 0.0) / height as f64;
+        let pix_orig = pos +
+            Vector3::new(0.0, 0.0, -focal_len) -
+            width as f64 / 2.0 * pix_delta_x -
+            height as f64 / 2.0 * pix_delta_y;
+
+        Camera {
+            pos,
+            pix_orig,
+            pix_delta_x,
+            pix_delta_y,
+        }
+    }
+
+    pub fn generate_ray(&self, p: Point2<u32>) -> Ray {
+        let pix_pos = self.pix_orig + p.x as f64 * self.pix_delta_x + p.y as f64 * self.pix_delta_y;
+        let dir = pix_pos - self.pos;
+
+        Ray::new(self.pos, dir)
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index 8786874..7021153 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,13 +1,15 @@
 mod cli;
 mod core;
+mod camera;
 
 use clap::Parser;
 use cli::{Cli, Size};
 use core::Ray;
 use image::{Rgb, RgbImage};
 use indicatif::ProgressBar;
-use nalgebra::{Point3, Vector3};
+use nalgebra::{Point2, Point3, Vector3};
 use palette::{LinSrgb, Srgb};
+use camera::Camera;
 
 fn hit_sphere(center: Point3<f64>, radius: f64, ray: &Ray) -> Option<f64> {
     let a = ray.dir.magnitude_squared();
@@ -40,22 +42,11 @@ fn main() {
     let mut image = RgbImage::new(width, height);
     let progress_bar = ProgressBar::new(height as u64);
 
-    let camera_pos = Point3::new(0.0, 0.0, 0.0);
-    let camera_focal_len = 1.0;
-
-    let viewport_height = 2.0;
-    let viewport_width = viewport_height * (width as f64 / height as f64);
-
-    let pixel_delta_x = Vector3::new(viewport_width, 0.0, 0.0) / width as f64;
-    let pixel_delta_y = Vector3::new(0.0, -viewport_height, 0.0) / height as f64;
-    let pixel_pos_orig = camera_pos + Vector3::new(0.0, 0.0, -camera_focal_len)
-        - width as f64 / 2.0 * pixel_delta_x
-        - height as f64 / 2.0 * pixel_delta_y;
+    let camera = Camera::new(Point3::new(0.0, 0.0, 0.0), width, height, 1.0);
 
     for y in 0..height {
         for x in 0..width {
-            let pixel_pos = pixel_pos_orig + x as f64 * pixel_delta_x + y as f64 * pixel_delta_y;
-            let ray = Ray::new(camera_pos, pixel_pos - camera_pos);
+            let ray = camera.generate_ray(Point2::new(x, y));
             let color: Srgb<f64> = Srgb::from_linear(ray_color(&ray));
 
             let r = (255.999 * color.red) as u8;