From 14b5b2b12577fd15e50192c42878237373bb39ef Mon Sep 17 00:00:00 2001
From: "max.nuding" <max.nuding@uni-konstanz.de>
Date: Fri, 8 Jul 2022 08:13:42 +0200
Subject: [PATCH] Add XY aligned rects

---
 src/main.rs    | 56 +++++++++++++++++++++++++++++++++++++++++++++++++-
 src/xy_rect.rs | 48 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 103 insertions(+), 1 deletion(-)
 create mode 100644 src/xy_rect.rs

diff --git a/src/main.rs b/src/main.rs
index 8b5b7e7..635fe97 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -15,6 +15,7 @@ use crate::image_texture::ImageTexture;
 use crate::noise::NoiseTexture;
 use crate::perlin::Perlin;
 use crate::texture::CheckerTexture;
+use crate::xy_rect::XyRect;
 
 mod vec3;
 mod ray;
@@ -28,6 +29,7 @@ mod texture;
 mod perlin;
 mod noise;
 mod image_texture;
+mod xy_rect;
 
 // Image
 const ASPECT_RATIO: f64 = 3.0 / 2.0;
@@ -42,6 +44,57 @@ struct Scene {
     pub background: Color
 }
 
+fn simple_light() -> Scene {
+    let mut world:HittableList = Vec::new();
+
+    let noise = NoiseTexture { noise: Perlin::new(), scale: 4.0 };
+    let noise_material = Arc::new(Material::Lambertian(Lambertian::textured(Arc::new(noise))));
+    world.push(Arc::new(Sphere {
+        center: Point3::new(0.0, -1000.0, 0.0),
+        radius: 1000.0,
+        material: Arc::clone(&noise_material)
+    }));
+    world.push(Arc::new(Sphere {
+        center: Point3::new(0.0, 2.0, 0.0),
+        radius: 2.0,
+        material: noise_material
+    }));
+
+
+    let difflight = Material::DiffuseLight(
+        // Brighter than 1.0/1.0/1.0 so it can light things
+        DiffuseLight::from(Color::new(4.0, 4.0, 4.0)));
+    world.push(Arc::new(XyRect {
+        x0: 3.0,
+        x1: 5.0,
+        y0: 1.0,
+        y1: 3.0,
+        k: -2.0,
+        material: Arc::new(difflight)
+    }));
+
+    let look_from = Point3::new(26.0, 3.0, 6.0);
+    let look_at = Point3::new(0.0, 2.0, 0.0);
+    let focus_dist = 2.0;
+
+    let cam = Camera::new(
+        look_from,
+        look_at,
+        Vec3::new(0.0, 1.0, 0.0),
+        ASPECT_RATIO,
+        20.0,
+        0.0,
+        focus_dist,
+        0.0,
+        1.0);
+
+    Scene {
+        world,
+        cam,
+        background: Color::default()
+    }
+}
+
 fn sun() -> Scene {
     let mut world:HittableList = Vec::new();
     let earth_material = Arc::new(
@@ -283,12 +336,13 @@ fn random_scene() -> Scene {
 
 fn main() {
     // World
-    let scene: u8 = 3;
+    let scene: u8 = 4;
     let scene_setup = match scene {
         0 => two_spheres(),
         1 => two_perlin_spheres(),
         2 => earth(),
         3 => sun(),
+        4 => simple_light(),
         _ => random_scene(),
     };
 
diff --git a/src/xy_rect.rs b/src/xy_rect.rs
new file mode 100644
index 0000000..4c5564f
--- /dev/null
+++ b/src/xy_rect.rs
@@ -0,0 +1,48 @@
+use std::sync::Arc;
+use crate::hittable::{HitRecord, Hittable};
+use crate::{Aabb, Material, Point3, Ray, Vec3};
+
+pub struct XyRect {
+    pub x0: f64,
+    pub x1: f64,
+    pub y0: f64,
+    pub y1: f64,
+    pub k: f64,
+    pub material: Arc<Material>
+}
+
+impl Hittable for XyRect {
+    fn hit(&self, ray: &Ray, t_min: f64, t_max: f64) -> Option<HitRecord> {
+        let t = (self.k - ray.origin().z()) / ray.direction().z();
+        if t < t_min || t > t_max {
+            return None;
+        }
+        let x = ray.origin().x() + t * ray.direction().x();
+        let y = ray.origin().y() + t * ray.direction().y();
+        if x < self.x0 || x > self.x1 || y < self.y0 || y > self.y1 {
+            return None;
+        }
+        let normal = Vec3::new(0.0, 0.0, 1.0);
+        let dot = ray.direction().dot(&normal);
+        let front_face = dot < 0.0;
+        let normal = if front_face { normal } else { -normal };
+        Some(HitRecord {
+            point: ray.at(t),
+            normal,
+            t,
+            u: (x-self.x0)/(self.x1-self.x0),
+            v: (y-self.y0)/(self.y1-self.y0),
+            front_face,
+            material: &self.material
+        })
+    }
+
+    fn bounding_box(&self, _time0: f64, _time1: f64) -> Option<Aabb> {
+        // The bounding box must have non-zero width in each dimension, so pad the Z
+        // dimension a small amount.
+        Some(Aabb {
+            minimum: Point3::new(self.x0, self.y0, self.k-0.0001),
+            maximum: Point3::new(self.x1, self.y1, self.k+0.0001),
+        })
+    }
+}