upd: diffuse material

3 files changed, 53 insertions, 11 deletions

diff --git a/src/calculus.rs b/src/calculus.rs
index a39c8a5..8865154 100644
--- a/src/calculus.rs
+++ b/src/calculus.rs
@@ -16,6 +16,43 @@ pub mod calculus {
             Self { x, y, z }
         }
 
+        fn random() -> Self {
+            let mut rng = rand::rng();
+            Self::new(
+                rng.random(),
+                rng.random(),
+                rng.random(),
+            )
+        }
+
+        fn random_range(min: f32, max: f32) -> Self {
+            let mut rng = rand::rng();
+            Self::new(
+                rng.random_range(min..max),
+                rng.random_range(min..max),
+                rng.random_range(min..max),
+            )
+        }
+
+        fn random_unit() -> Vec3 {
+            loop {
+                let p = Self::random_range(-1.0, 1.0);
+                let lensq = p.mag_sqr();
+                if f32::EPSILON < lensq && lensq <= 1.0 {
+                    return p.scalar_mul(1.0 / lensq.sqrt())
+                }
+            }
+        }
+
+        pub fn random_on_hemisphere(normal: &Vec3) -> Vec3 {
+            let on_unit_sphere = Self::random_unit();
+            if on_unit_sphere.dot_prod(normal) > 0.0 {
+                on_unit_sphere
+            } else {
+                on_unit_sphere.scalar_mul(-1.0)
+            }
+        }
+
         pub fn add(&self, other: &Self) -> Self {
             Self {
                 x: self.x + other.x,
diff --git a/src/camera.rs b/src/camera.rs
index 8e9cf68..ec37c70 100644
--- a/src/camera.rs
+++ b/src/camera.rs
@@ -13,6 +13,7 @@ pub struct Camera {
     delta_pixel_u: Vec3,
     delta_pixel_v: Vec3,
     pixel_samples_scale: f32,
+    max_depth: usize,
 }
 
 impl Camera {
@@ -45,6 +46,8 @@ impl Camera {
             &delta_pixel_u.add(&delta_pixel_u).scalar_mul(0.5)
         );
 
+        let max_depth = 50;
+
         Self {
             aspect_ratio,
             image_width,
@@ -55,6 +58,7 @@ impl Camera {
             delta_pixel_v,
             samples_per_pixel,
             pixel_samples_scale,
+            max_depth
         }
     }
 
@@ -73,18 +77,18 @@ impl Camera {
         }
     }
 
-    fn ray_color(&self, ray: &Ray, world: &HittableList) -> Color {
+    fn ray_color(&self, ray: &Ray, world: &HittableList, depth: usize) -> Color {
+        if depth <= 0 {
+            return Color::new(0.0, 0.0, 0.0);
+        }
+
         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 direction = Vec3::random_on_hemisphere(&rec.normal);
+            let origin = rec.position.clone();
+            let r = Ray { origin, direction };
+            return self.ray_color(&r, world, depth - 1).mul_scalar(0.5);
         }
 
         let unit_direction = ray.direction.unit();
@@ -97,10 +101,11 @@ impl Camera {
     pub fn render(&self, display_buffer: &mut DisplayBuffer, world: &HittableList) {
         (0..self.image_height).for_each(|j| {
             (0..self.image_width).for_each(|i| {
+                println!("Processing line {} col {}", j, i);
                 let mut pixel_color = Color::new(0.0, 0.0, 0.0);
                 (0..self.samples_per_pixel).for_each(|_| {
                     let r = self.get_ray(i, j);
-                    let ray_color = self.ray_color(&r, world);
+                    let ray_color = self.ray_color(&r, world, self.max_depth);
                     pixel_color = pixel_color.add(&ray_color);
                 });
                 pixel_color = pixel_color.mul_scalar(self.pixel_samples_scale);
diff --git a/src/global.rs b/src/global.rs
index 3f74ba1..3975609 100644
--- a/src/global.rs
+++ b/src/global.rs
@@ -3,7 +3,7 @@ use crate::interval::Interval;
 
 // "Ideal" aspect ratio, allowing fraction
 pub const ASPECT_RATIO: f32 = 16.0f32 / 9.0f32;
-pub const IMG_WIDTH: usize = 1000;
+pub const IMG_WIDTH: usize = 400;
 pub const IMG_HEIGHT: usize = get_image_height(IMG_WIDTH, ASPECT_RATIO);
 
 pub const VIEWPORT_HEIGHT: f32 = 2.0;