Initial

src/hittable.rs

@@ -0,0 +1,64 @@
+use crate::{Point3, Ray, Vec3};
+use crate::material::{Material};
+
+#[derive(Debug, Clone, Copy)]
+pub struct HitRecord<'material> {
+    pub point: Point3,
+    pub normal: Vec3,
+    pub t: f64,
+    pub front_face: bool,
+    pub material: &'material Material
+}
+
+pub trait Hittable {
+    fn hit(&self, ray: &Ray, t_min: f64, t_max: f64) -> Option<HitRecord>;
+}
+pub struct Sphere {
+    pub center: Point3,
+    pub radius: f64,
+    pub material: Material
+}
+impl Sphere {
+    pub fn new(center: Point3, radius: f64, material: Material) -> Sphere {
+        Sphere { center, radius, material }
+    }
+}
+impl Default for Sphere {
+    fn default() -> Self {
+        Sphere {
+            center: Point3::default(),
+            radius: 0.0,
+            material: Material::default()
+        }
+    }
+}
+
+impl Hittable for Sphere {
+    fn hit(&self, ray: &Ray, t_min: f64, t_max: f64) -> Option<HitRecord> {
+        let oc = &ray.origin() - &self.center;
+        let a = ray.direction().length_squared();
+        let half_b = oc.dot(&ray.direction());
+        let c = oc.length_squared() - &self.radius * &self.radius;
+        let discriminant = half_b * half_b - a * c;
+        if discriminant < 0.0 { return None; }
+
+        let sqrtd = f64::sqrt(discriminant);
+        let root = (-half_b - sqrtd) / a;
+        if root < t_min || t_max < root {
+            let root = (-half_b + sqrtd) / a;
+            if root < t_min || t_max < root { return None; }
+        }
+
+        let point = ray.at(root);
+        let normal = (point - self.center) / self.radius;
+        let front_face = ray.direction().dot(&normal) < 0.0;
+        let normal = if front_face { normal } else { -normal };
+        Some(HitRecord {
+            point,
+            normal,
+            t: root,
+            front_face,
+            material: &self.material
+        })
+    }
+}