Add environment mapping for background.

rtiow/src/renderer.rs

@@ -19,6 +19,8 @@ use camera::Camera;
 use hitable::Hit;
 use ray::Ray;
 use scenes;
+use texture::EnvMap;
+use texture::Texture;
 use vec3::Vec3;
 
 #[derive(Debug)]
@@ -115,32 +117,47 @@ pub struct Scene {
     pub width: usize,
     pub height: usize,
     pub global_illumination: bool,
+    pub env_map: Option<EnvMap>,
 }
 
 // color will trace ray up to 50 bounces deep accumulating color as it goes.  If
 // global_illumination is true, a default light background color is assumed and will light the
 // world.  If false, it is expected the scene has emissive light sources.
-fn color(r: Ray, world: &Hit, depth: usize, global_illumination: bool) -> Vec3 {
+fn color(
+    r: Ray,
+    world: &Hit,
+    depth: usize,
+    global_illumination: bool,
+    env_map: &Option<EnvMap>,
+) -> Vec3 {
     if let Some(rec) = world.hit(r, 0.001, std::f32::MAX) {
         let (u, v) = rec.uv;
         let emitted = rec.material.emitted(u, v, rec.p);
         let scatter_response = rec.material.scatter(&r, &rec);
         if depth < 50 && scatter_response.reflected {
-            return emitted + scatter_response.attenutation * color(
-                scatter_response.scattered,
-                world,
-                depth + 1,
-                global_illumination,
-            );
+            return emitted
+                + scatter_response.attenutation
+                    * color(
+                        scatter_response.scattered,
+                        world,
+                        depth + 1,
+                        global_illumination,
+                        env_map,
+                    );
         } else {
             return emitted;
         }
     }
     if global_illumination {
-        // No hit, choose color from background.
-        let unit_direction = r.direction.unit_vector();
-        let t = 0.5 * (unit_direction.y + 1.);
-        return Vec3::new(1., 1., 1.) * (1. - t) + Vec3::new(0.5, 0.7, 1.) * t;
+        return match env_map {
+            Some(env_map) => env_map.color(r.direction.unit_vector()),
+            None => {
+                let unit_direction = r.direction.unit_vector();
+                // No hit, choose color from background.
+                let t = 0.5 * (unit_direction.y + 1.);
+                Vec3::new(1., 1., 1.) * (1. - t) + Vec3::new(0.5, 0.7, 1.) * t
+            }
+        };
     }
     // No global illumination, so background is black.
     Vec3::new(0., 0., 0.)
@@ -151,7 +168,13 @@ fn trace_pixel(x: usize, y: usize, scene: &Scene) -> Vec3 {
     let u = (rng.gen_range::<f32>(0., 1.) + x as f32) / scene.width as f32;
     let v = (rng.gen_range::<f32>(0., 1.) + y as f32) / scene.height as f32;
     let ray = scene.camera.get_ray(u, v);
-    color(ray, scene.world.as_ref(), 0, scene.global_illumination)
+    color(
+        ray,
+        scene.world.as_ref(),
+        0,
+        scene.global_illumination,
+        &scene.env_map,
+    )
 }
 
 fn render_worker(

rtiow/src/scenes/bench.rs

@@ -72,5 +72,6 @@ pub fn new(opt: &Opt) -> Scene {
         width: opt.width,
         height: opt.height,
         global_illumination: true,
+        env_map: None,
     }
 }

rtiow/src/scenes/book.rs

@@ -14,6 +14,7 @@ use renderer::Scene;
 use sphere::Sphere;
 use texture::CheckerTexture;
 use texture::ConstantTexture;
+use texture::EnvMap;
 use vec3::Vec3;
 
 pub fn new(opt: &Opt) -> Scene {
@@ -44,6 +45,8 @@ pub fn new(opt: &Opt) -> Scene {
     } else {
         Box::new(HitableList::new(random_scene(ground_color)))
     };
+    let skybox_bytes = include_bytes!("../../images/envmap.jpg");
+    let skybox = image::load_from_memory(skybox_bytes).unwrap().to_rgb();
     Scene {
         camera,
         world,
@@ -51,6 +54,7 @@ pub fn new(opt: &Opt) -> Scene {
         width: opt.width,
         height: opt.height,
         global_illumination: true,
+        env_map: Some(EnvMap::new(skybox)),
     }
 }
 

rtiow/src/scenes/bvh.rs

@@ -66,5 +66,6 @@ pub fn new(opt: &Opt) -> Scene {
         width: opt.width,
         height: opt.height,
         global_illumination: true,
+        env_map: None,
     }
 }

rtiow/src/scenes/cornell_box.rs

@@ -133,5 +133,6 @@ pub fn new(opt: &Opt) -> Scene {
         width: opt.width,
         height: opt.height,
         global_illumination: false,
+        env_map: None,
     }
 }

rtiow/src/scenes/cornell_smoke.rs

@@ -118,5 +118,6 @@ pub fn new(opt: &Opt) -> Scene {
         width: opt.width,
         height: opt.height,
         global_illumination: false,
+        env_map: None,
     }
 }

rtiow/src/scenes/final_scene.rs

@@ -169,5 +169,6 @@ pub fn new(opt: &Opt) -> Scene {
         width: opt.width,
         height: opt.height,
         global_illumination: false,
+        env_map: None,
     }
 }

rtiow/src/scenes/perlin_debug.rs

@@ -69,5 +69,6 @@ pub fn new(opt: &Opt) -> Scene {
         width: opt.width,
         height: opt.height,
         global_illumination: true,
+        env_map: None,
     }
 }

rtiow/src/scenes/test.rs

@@ -145,5 +145,6 @@ pub fn new(opt: &Opt) -> Scene {
         width: opt.width,
         height: opt.height,
         global_illumination: false,
+        env_map: None,
     }
 }

rtiow/src/scenes/tutorial.rs

@@ -73,5 +73,6 @@ pub fn new(opt: &Opt) -> Scene {
         width: opt.width,
         height: opt.height,
         global_illumination: true,
+        env_map: None,
     }
 }

rtiow/src/texture/envmap.rs

@@ -0,0 +1,27 @@
+use std::f32;
+
+use image::RgbImage;
+
+use texture::ImageTexture;
+use texture::Texture;
+use vec3::Vec3;
+
+#[derive(Debug)]
+pub struct EnvMap {
+    img_tex: ImageTexture,
+}
+
+impl EnvMap {
+    pub fn new(img: RgbImage) -> EnvMap {
+        EnvMap {
+            img_tex: ImageTexture::new(img),
+        }
+    }
+    pub fn color(&self, ray: Vec3) -> Vec3 {
+        let zero = Vec3::new(0., 0., 0.);
+        let u = ray.x.atan2(ray.z) / f32::consts::PI /2.0 + 0.5;
+        let v = ray.y / 2.0 + 0.5;
+        // TODO(wathiede): properly wrap sphere to lat/lon.
+        self.img_tex.value(u, v, zero)
+    }
+}

rtiow/src/texture/image.rs

@@ -3,6 +3,7 @@ use image::RgbImage;
 use texture::Texture;
 use vec3::Vec3;
 
+#[derive(Debug)]
 pub struct ImageTexture {
     img: RgbImage,
     width: f32,

rtiow/src/texture/mod.rs

@@ -2,8 +2,10 @@ mod checker;
 mod constant;
 mod image;
 mod noise;
+mod envmap;
 pub use texture::checker::CheckerTexture;
 pub use texture::constant::ConstantTexture;
+pub use texture::envmap::EnvMap;
 pub use texture::image::ImageTexture;
 pub use texture::noise::NoiseTexture;