From c6b0fb59ae432876b0ad4014750479c855ddd277 Mon Sep 17 00:00:00 2001
From: "max.nuding" <max.nuding@uni-konstanz.de>
Date: Mon, 11 Jul 2022 07:33:25 +0200
Subject: [PATCH] Add rotate

---
 src/rotate_y.rs | 86 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 src/rotate_y.rs

diff --git a/src/rotate_y.rs b/src/rotate_y.rs
new file mode 100644
index 0000000..b922717
--- /dev/null
+++ b/src/rotate_y.rs
@@ -0,0 +1,86 @@
+use crate::hittable::{HitRecord, Hittable};
+use crate::{Aabb, Point3, Ray, Vec3};
+
+pub struct RotateY<H: Hittable> {
+    hittable: H,
+    sin_theta: f64,
+    cos_theta: f64,
+    bounding_box: Option<Aabb>
+}
+
+impl<H: Hittable> RotateY<H> {
+    pub fn new(hittable: H, degrees: f64) -> Self {
+        let radians = degrees.to_radians();
+        let sin_theta = radians.sin();
+        let cos_theta = radians.cos();
+        let mut bounding_box = hittable.bounding_box(0.0, 1.0);
+
+        if let Some(bbox) = bounding_box {
+            let mut min = Point3::new(f64::INFINITY, f64::INFINITY, f64::INFINITY);
+            let mut max = Point3::new(f64::NEG_INFINITY, f64::NEG_INFINITY, f64::NEG_INFINITY);
+            for i in 0..2 {
+                for j in 0..2 {
+                    for k in 0..2 {
+                        let x = (i as f64)*bbox.maximum.x() + ((1 - i) as f64)*bbox.minimum.x();
+                        let y = (i as f64)*bbox.maximum.y() + ((1 - j) as f64)*bbox.minimum.y();
+                        let z = (i as f64)*bbox.maximum.z() + ((1 - k) as f64)*bbox.minimum.z();
+
+                        let x = cos_theta * x + sin_theta * z;
+                        let z = -sin_theta * x + cos_theta * z;
+
+                        let tester = Vec3::new(x, y, z);
+                        for c in 0..3 {
+                            min[c] = min[c].min(tester[c]);
+                            max[c] = max[c].max(tester[c]);
+                        }
+                    }
+                }
+            }
+            bounding_box = Some(Aabb {
+                minimum: min,
+                maximum: max
+            });
+        }
+        Self { hittable, sin_theta, cos_theta, bounding_box }
+    }
+}
+impl<H: Hittable> Hittable for RotateY<H> {
+    fn hit(&self, ray: &Ray, t_min: f64, t_max: f64) -> Option<HitRecord> {
+        let mut origin = ray.origin();
+        let mut direction = ray.direction();
+
+        origin[0] = self.cos_theta * ray.origin()[0] - self.sin_theta*ray.origin()[2];
+        origin[2] = self.sin_theta * ray.origin()[0] + self.cos_theta*ray.origin()[2];
+
+        direction[0] = self.cos_theta * ray.direction()[0] - self.sin_theta*ray.direction()[2];
+        direction[2] = self.sin_theta * ray.direction()[0] + self.cos_theta*ray.direction()[2];
+        let rotated = Ray::new(origin, direction, ray.time());
+        match self.hittable.hit(&rotated, t_min, t_max) {
+            Some(rec) => {
+                let mut p = rec.point;
+                let mut normal = rec.normal;
+                p[0] = self.cos_theta*rec.point[0] + self.sin_theta * rec.point[2];
+                p[2] = -self.sin_theta*rec.point[0] + self.cos_theta * rec.point[2];
+
+                normal[0] = self.cos_theta*rec.normal[0] + self.sin_theta * rec.normal[2];
+                normal[2] = -self.sin_theta*rec.normal[0] + self.cos_theta * rec.normal[2];
+                let mut new_rec = HitRecord {
+                    point: p,
+                    normal,
+                    t: rec.t,
+                    u: rec.u,
+                    v: rec.v,
+                    front_face: rec.front_face,
+                    material: rec.material,
+                };
+                new_rec.normalized(&rotated);
+                Some(new_rec)
+            },
+            _ =>  None
+        }
+    }
+
+    fn bounding_box(&self, _time0: f64, _time1: f64) -> Option<Aabb> {
+        self.bounding_box
+    }
+}