From 5fb34460b02b2b151dd775e43675bd4f09d2633a Mon Sep 17 00:00:00 2001
From: Rosyid Haryadi <rosyid_haryadi@protonmail.com>
Date: Sat, 1 Mar 2025 23:07:43 +0700
Subject: refactor camera

---
 src/camera.rs | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 src/camera.rs

(limited to 'src/camera.rs')

diff --git a/src/camera.rs b/src/camera.rs
new file mode 100644
index 0000000..587a312
--- /dev/null
+++ b/src/camera.rs
@@ -0,0 +1,91 @@
+use crate::calculus::calculus::{Point3, Ray, Vec3};
+use crate::global::{get_image_height, Color, DisplayBuffer, Pixel, ASPECT_RATIO, CAMERA_CENTER, FOCAL_LENGTH, IMG_WIDTH, VIEWPORT_HEIGHT};
+use crate::interval::Interval;
+use crate::object::{HitRecord, Hittable, HittableList, Sphere};
+
+pub struct Camera {
+    pub aspect_ratio: f32,
+    pub image_width: usize,
+    image_height: usize,
+    center: Point3,
+    pixel_upper_left: Point3,
+    delta_pixel_u: Vec3,
+    delta_pixel_v: Vec3,
+}
+
+impl Camera {
+    pub fn new() -> Self {
+        let aspect_ratio = ASPECT_RATIO;
+
+        let image_width = IMG_WIDTH;
+        let image_height = get_image_height(image_width, aspect_ratio);
+
+        let center = CAMERA_CENTER;
+        let focal_length = FOCAL_LENGTH;
+
+        let viewport_height = VIEWPORT_HEIGHT;
+        let viewport_width = viewport_height * (image_width as f32 / image_height as f32);
+
+        let viewport_hor_vector = Vec3{ x: viewport_width, y: 0.0, z: 0.0 };
+        let viewport_ver_vector = Vec3 { x: 0.0, y: -1f32 * viewport_height, z: 0.0 };
+
+        let delta_pixel_u = viewport_hor_vector.scalar_mul(1.0 / image_width as f32);
+        let delta_pixel_v = viewport_ver_vector.scalar_mul(1.0 / image_height as f32);
+
+        let viewport_upper_left = center
+            .sub(&Vec3 { x: 0f32, y: 0f32, z: focal_length})
+            .sub(&viewport_hor_vector.scalar_mul(0.5))
+            .sub(&viewport_ver_vector.scalar_mul(0.5));
+        let pixel_upper_left = viewport_upper_left.add(
+            &delta_pixel_u.add(&delta_pixel_u).scalar_mul(0.5)
+        );
+
+        Self {
+            aspect_ratio,
+            image_width,
+            image_height,
+            center,
+            pixel_upper_left,
+            delta_pixel_u,
+            delta_pixel_v,
+        }
+    }
+
+    fn ray_color(&self, ray: &Ray, world: &HittableList) -> Color {
+        let mut rec = HitRecord::default();
+        let ray_t = Interval::new(0.0, f32::INFINITY);
+        if world.hit(ray, ray_t, &mut rec) {
+            let color = Color::new(1.0, 1.0, 1.0)
+                .add(&Color::new(
+                    rec.normal.x,
+                    rec.normal.y,
+                    rec.normal.z)
+                )
+                .mul_scalar(0.5);
+            return color;
+        }
+
+        let unit_direction = ray.direction.unit();
+        let a = 0.5 * (unit_direction.y + 1.0);
+        let color1 = Color::new(1.0, 1.0, 1.0).mul_scalar(1.0 - a);
+        let color2 = Color::new(0.5, 0.7, 1.0).mul_scalar(a);
+        color1.add(&color2)
+    }
+
+    pub fn render(&self, display_buffer: &mut DisplayBuffer, world: &HittableList) {
+        (0..self.image_height).for_each(|j| {
+            (0..self.image_width).for_each(|i| {
+                let pixel_center = self.pixel_upper_left
+                    .add(&self.delta_pixel_u.scalar_mul(i as f32))
+                    .add(&self.delta_pixel_v.scalar_mul(j as f32));
+                let ray_direction = pixel_center.sub(&self.center);
+                let ray = Ray {
+                    origin: &self.center,
+                    direction: &ray_direction,
+                };
+                let color = self.ray_color(&ray, &world);
+                display_buffer[j][i] = Pixel::from_color(&color);
+            })
+        })
+    }
+}
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