rtiow: break project into multiple workspaces.

rtiow/renderer/src/sphere.rs

@@ -0,0 +1,89 @@
+use std::f32::consts::PI;
+
+use crate::aabb::AABB;
+use crate::hitable::Hit;
+use crate::hitable::HitRecord;
+use crate::material::Material;
+use crate::ray::Ray;
+use crate::vec3::dot;
+use crate::vec3::Vec3;
+
+pub struct Sphere<M>
+where
+    M: Material,
+{
+    center: Vec3,
+    radius: f32,
+    material: M,
+}
+
+pub fn get_sphere_uv(p: Vec3) -> (f32, f32) {
+    let phi = p.z.atan2(p.x);
+    let theta = p.y.asin();
+    let u = 1. - (phi + PI) / (2. * PI);
+    let v = (theta + PI / 2.) / PI;
+    (u, v)
+}
+
+impl<M> Sphere<M>
+where
+    M: Material,
+{
+    pub fn new<V>(center: V, radius: f32, material: M) -> Sphere<M>
+    where
+        V: Into<Vec3>,
+    {
+        Sphere {
+            center: center.into(),
+            radius,
+            material,
+        }
+    }
+}
+
+impl<M> Hit for Sphere<M>
+where
+    M: Material,
+{
+    fn hit(&self, r: Ray, t_min: f32, t_max: f32) -> Option<HitRecord> {
+        let oc = r.origin - self.center;
+        let a = dot(r.direction, r.direction);
+        let b = dot(oc, r.direction);
+        let c = dot(oc, oc) - self.radius * self.radius;
+        let discriminant = b * b - a * c;
+        if discriminant > 0. {
+            let temp = (-b - (b * b - a * c).sqrt()) / a;
+            if temp < t_max && temp > t_min {
+                let point = r.point_at_parameter(temp);
+                let uv = get_sphere_uv((point - self.center) / self.radius);
+                return Some(HitRecord {
+                    t: temp,
+                    uv,
+                    p: point,
+                    normal: (point - self.center) / self.radius,
+                    material: &self.material,
+                });
+            }
+            let temp = (-b + (b * b - a * c).sqrt()) / a;
+            if temp < t_max && temp > t_min {
+                let point = r.point_at_parameter(temp);
+                let uv = get_sphere_uv((point - self.center) / self.radius);
+                return Some(HitRecord {
+                    t: temp,
+                    uv,
+                    p: point,
+                    normal: (point - self.center) / self.radius,
+                    material: &self.material,
+                });
+            }
+        }
+        None
+    }
+
+    fn bounding_box(&self, _t_min: f32, _t_max: f32) -> Option<AABB> {
+        Some(AABB::new(
+            self.center - Vec3::new(self.radius, self.radius, self.radius),
+            self.center + Vec3::new(self.radius, self.radius, self.radius),
+        ))
+    }
+}