Produce images

assignment-1/.gitignore

@@ -1 +1,2 @@
 /target
+*.ppm

assignment-1/Cargo.lock

@@ -14,7 +14,9 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "clap",
+ "itertools",
  "num",
+ "ordered-float",
 ]
 
 [[package]]
@@ -72,6 +74,12 @@ dependencies = [
  "os_str_bytes",
 ]
 
+[[package]]
+name = "either"
+version = "1.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7fcaabb2fef8c910e7f4c7ce9f67a1283a1715879a7c230ca9d6d1ae31f16d91"
+
 [[package]]
 name = "errno"
 version = "0.2.8"
@@ -130,6 +138,15 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "itertools"
+version = "0.10.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b0fd2260e829bddf4cb6ea802289de2f86d6a7a690192fbe91b3f46e0f2c8473"
+dependencies = [
+ "either",
+]
+
 [[package]]
 name = "libc"
 version = "0.2.139"
@@ -227,6 +244,15 @@ version = "1.17.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6f61fba1741ea2b3d6a1e3178721804bb716a68a6aeba1149b5d52e3d464ea66"
 
+[[package]]
+name = "ordered-float"
+version = "3.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d84eb1409416d254e4a9c8fa56cc24701755025b458f0fcd8e59e1f5f40c23bf"
+dependencies = [
+ "num-traits",
+]
+
 [[package]]
 name = "os_str_bytes"
 version = "6.4.1"

assignment-1/Cargo.toml

@@ -8,4 +8,6 @@ edition = "2021"
 [dependencies]
 anyhow = "1.0.68"
 clap = { version = "4.1.4", features = ["derive"] }
+itertools = "0.10.5"
 num = { version = "0.4.0", features = ["serde"] }
+ordered-float = "3.4.0"

assignment-1/src/image.rs

@@ -0,0 +1,35 @@
+use std::io::{Result, Write};
+
+/// A 24-bit pixel represented by a red, green, and blue value.
+#[derive(Clone, Copy, Default, Debug)]
+pub struct Pixel(pub u8, pub u8, pub u8);
+
+/// A representation of an image
+pub struct Image {
+  /// Width in pixels
+  pub(crate) width: usize,
+
+  /// Height in pixels
+  pub(crate) height: usize,
+
+  /// Pixel data in row-major form.
+  pub(crate) data: Vec<Pixel>,
+}
+
+impl Image {
+  /// Write the image in PPM format to a file.
+  pub fn write(&self, mut w: impl Write) -> Result<()> {
+    // Header
+    let header = format!("P3 {} {} 255\n", self.width, self.height);
+    w.write_all(header.as_bytes())?;
+
+    // Pixel data
+    for pixel in self.data.iter() {
+      let Pixel(red, green, blue) = pixel;
+      let pixel = format!("{red} {green} {blue}\n");
+      w.write_all(pixel.as_bytes())?;
+    }
+
+    Ok(())
+  }
+}

assignment-1/src/input_file.rs

@@ -54,11 +54,17 @@ pub fn parse_input_file(path: impl AsRef<Path>) -> Result<Scene> {
 
         "hfov" => scene.hfov = parts[0],
         "bkgcolor" => scene.bkg_color = read_vec3()?,
-        "mtlcolor" => material_color = Some(read_vec3()?),
+
+        "mtlcolor" => {
+          let idx = scene.material_colors.len();
+          material_color = Some(idx);
+          scene.material_colors.push(read_vec3()?);
+        },
 
         "sphere" => scene.objects.push(Object::Sphere(Sphere {
           center: read_vec3()?,
           radius: parts[3],
+          material: material_color.unwrap(),
         })),
         _ => bail!("Unknown keyword {keyword}"),
       }

assignment-1/src/main.rs

@@ -1,21 +1,30 @@
 #[macro_use]
 extern crate anyhow;
 
+mod image;
 mod input_file;
 mod ray;
 mod scene_data;
 mod vec3;
 mod view;
 
+use std::fs::File;
 use std::path::PathBuf;
 
 use anyhow::Result;
 use clap::Parser;
+use itertools::Itertools;
+use ordered_float::NotNan;
 
+use crate::image::{Image, Pixel};
 use crate::input_file::parse_input_file;
+use crate::ray::Ray;
+use crate::scene_data::Object;
 use crate::vec3::Vec3;
 use crate::view::Rect;
 
+const ARBITRARY_D: f64 = 2.0;
+
 /// Simple raycaster.
 #[derive(Parser)]
 #[clap(author, version, about, long_about = None)]
@@ -26,14 +35,20 @@ struct Opt {
   ///
   ///     imsize [width] [height]
   ///
-  /// Where `imsize' is a keyword, and `width' and `height' are integer values
-  /// denoting the desired size of the image to be generated.
+  /// Where `imsize' is a keyword, and `width' and `height' are integer values denoting the desired
+  /// size of the image to be generated.
   #[clap()]
   input_path: PathBuf,
+
+  #[clap()]
+  output_path: Option<PathBuf>,
 }
 
 fn main() -> Result<()> {
   let opt = Opt::parse();
+  let out_file = opt
+    .output_path
+    .unwrap_or_else(|| opt.input_path.with_extension("ppm"));
 
   let scene = parse_input_file(&opt.input_path)?;
   println!("Scene: {scene:?}");
@@ -42,20 +57,88 @@ fn main() -> Result<()> {
   let u = Vec3::cross(scene.view_dir, scene.up_dir).unit();
   let v = Vec3::cross(u, scene.view_dir).unit();
 
+  // Compute dimensions of viewing window based on field of view
+  let viewing_width = {
+    // Divide the angle in 2 since we are trying to use trig rules so we must get it from a right
+    // triangle
+    let half_hfov = scene.hfov / 2.0;
+
+    // tan(hfov / 2) = w / 2d
+    let w_over_2d = half_hfov.tan();
+
+    // To find the viewing width we must multiply by 2d now
+    w_over_2d * 2.0 * ARBITRARY_D
+  };
+  let aspect_ratio = scene.image_width as f64 / scene.image_height as f64;
+  let viewing_height = viewing_width / aspect_ratio;
+
   // Compute viewing window corners
   // TODO: See slide 101
-  // Also need to reverse calculation for d based on hfov
   let n = scene.view_dir.unit();
-  let d = 1.0;
+  #[rustfmt::skip] // Otherwise this line wraps over
   let view_window = Rect {
-    upper_left: scene.eye_pos + n * d, // + ...
-    upper_right: scene.eye_pos + n * d,
-    lower_left: scene.eye_pos + n * d,
-    lower_right: scene.eye_pos + n * d,
+    upper_left: scene.eye_pos + n * ARBITRARY_D - u * (viewing_width / 2.0) + v * (viewing_height / 2.0),
+    upper_right: scene.eye_pos + n * ARBITRARY_D + u * (viewing_width / 2.0) + v * (viewing_height / 2.0),
+    lower_left: scene.eye_pos + n * ARBITRARY_D - u * (viewing_width / 2.0) - v * (viewing_height / 2.0),
+    lower_right: scene.eye_pos + n * ARBITRARY_D + u * (viewing_width / 2.0) - v * (viewing_height / 2.0),
+  };
+
+  // Translate image pixels to real-world 3d coords
+  let pixel_translation = {
+    let dx = view_window.upper_right - view_window.upper_left;
+    let pixel_base_x = dx / scene.image_width as f64;
+
+    let dy = view_window.lower_left - view_window.upper_left;
+    let pixel_base_y = dy / scene.image_height as f64;
+
+    move |px: usize, py: usize| {
+      let x_component = view_window.upper_left + pixel_base_x * px as f64;
+      let y_component = view_window.upper_left + pixel_base_y * py as f64;
+      x_component + y_component
+    }
   };
 
   // Loop through every single pixel of the output file
-  for (px, py) in (0..scene.image_width).zip(0..scene.image_height) {}
+  let mut pixels =
+    vec![Pixel::default(); scene.image_width * scene.image_width];
+  for (px, py) in (0..scene.image_width).cartesian_product(0..scene.image_height) {
+    let pixel_in_space = pixel_translation(px, py);
+    let ray = Ray::from_endpoints(scene.eye_pos, pixel_in_space);
+
+    let earliest_intersection = scene
+      .objects
+      .iter()
+      .filter_map(|object| {
+        let sphere = match object {
+          Object::Sphere(v) => v,
+          _ => return None, // TODO: Handle other object types for intersection as well
+        };
+
+        ray.intersects_at(sphere).map(|t| (t, sphere))
+      })
+      .min_by_key(|(t, _)| NotNan::new(*t).unwrap());
+
+    let pixel_color = match earliest_intersection {
+      Some((_, sphere)) => scene.material_colors[sphere.material],
+      // There was no intersection, so this should default to the background color
+      None => scene.bkg_color,
+    };
+
+    // println!("({px}, {py}): {intersection:?}\t{ray:?} {sphere:?}");
+
+    pixels[py * scene.image_height + px] = pixel_color.to_pixel();
+  }
+
+  let image = Image {
+    width: scene.image_width,
+    height: scene.image_height,
+    data: pixels,
+  };
+
+  {
+    let file = File::create(&out_file)?;
+    image.write(file)?;
+  }
 
   Ok(())
 }

assignment-1/src/ray.rs

@@ -5,31 +5,41 @@ use crate::vec3::Vec3;
 ///
 /// That means at any time t: f64, the point represented by origin + direction * time occurs on the
 /// ray.
+#[derive(Debug)]
 pub struct Ray {
   origin: Vec3,
   direction: Vec3,
 }
 
 impl Ray {
+  /// Construct a ray from endpoints
+  pub fn from_endpoints(start: Vec3, end: Vec3) -> Self {
+    let delta = (end - start).unit();
+    Ray {
+      origin: start,
+      direction: delta,
+    }
+  }
+
   /// Evaluate the ray at a certain point in time, yielding a point
   pub fn eval(&self, time: f64) -> Vec3 {
     self.origin + self.direction * time
   }
-}
 
-/// Given a ray and a sphere, returns the first time at which this ray intersects the sphere.
-///
-/// If there is no intersection point, returns None.
-pub fn ray_intersection_time(ray: &Ray, sphere: &Sphere) -> Option<f64> {
-  let a =
-    ray.direction.x.powi(2) + ray.direction.y.powi(2) + ray.direction.z.powi(2);
+  /// Given a sphere, returns the first time at which this ray intersects the sphere.
+  ///
+  /// If there is no intersection point, returns None.
+  pub fn intersects_at(&self, sphere: &Sphere) -> Option<f64> {
+    let a = self.direction.x.powi(2)
+      + self.direction.y.powi(2)
+      + self.direction.z.powi(2);
     let b = 2.0
-    * (ray.direction.x * (ray.origin.x - sphere.center.x)
-      + ray.direction.y * (ray.origin.y - sphere.center.y)
-      + ray.direction.z * (ray.origin.z - sphere.center.z));
-  let c = (ray.origin.x - sphere.center.x).powi(2)
-    + (ray.origin.y - sphere.center.y).powi(2)
-    + (ray.origin.z - sphere.center.z).powi(2)
+      * (self.direction.x * (self.origin.x - sphere.center.x)
+        + self.direction.y * (self.origin.y - sphere.center.y)
+        + self.direction.z * (self.origin.z - sphere.center.z));
+    let c = (self.origin.x - sphere.center.x).powi(2)
+      + (self.origin.y - sphere.center.y).powi(2)
+      + (self.origin.z - sphere.center.z).powi(2)
       - sphere.radius.powi(2);
     let discriminant = b * b - 4.0 * a * c;
 
@@ -52,6 +62,7 @@ pub fn ray_intersection_time(ray: &Ray, sphere: &Sphere) -> Option<f64> {
       // Probably hit some NaN or Infinity value due to faulty inputs...
       _ => unreachable!("Invalid determinant value: {discriminant}"),
     }
+  }
 }
 
 #[cfg(test)]
@@ -59,7 +70,7 @@ mod tests {
   use crate::scene_data::Sphere;
   use crate::vec3::Vec3;
 
-  use super::{ray_intersection_time, Ray};
+  use super::Ray;
 
   #[test]
   fn practice_problem_slide_154() {
@@ -72,7 +83,7 @@ mod tests {
       radius: 4.0,
     };
 
-    let point = ray_intersection_time(&ray, &sphere).map(|t| ray.eval(t));
+    let point = ray.intersects_at(&sphere).map(|t| ray.eval(t));
 
     // the intersection point in this case is (0, 0, -6)
     assert_eq!(point, Some(Vec3::new(0.0, 0.0, -6.0)));
@@ -90,6 +101,6 @@ mod tests {
     };
 
     // oops! In this case, the ray does not intersect the sphere.
-    assert_eq!(ray_intersection_time(&ray, &sphere), None);
+    assert_eq!(ray.intersects_at(&sphere), None);
   }
 }

assignment-1/src/scene_data.rs

@@ -4,6 +4,9 @@ use crate::vec3::Vec3;
 pub struct Sphere {
   pub center: Vec3,
   pub radius: f64,
+
+  /// Index into the scene's material color list
+  pub material: usize,
 }
 
 #[derive(Debug)]
@@ -32,8 +35,6 @@ pub struct Scene {
   /// Background color
   pub bkg_color: Vec3,
 
-  /// Material color
-  pub mtl_color: Vec3,
-
+  pub material_colors: Vec<Vec3>,
   pub objects: Vec<Object>,
 }

assignment-1/src/vec3.rs

@@ -1,7 +1,9 @@
-use std::ops::{Add, Mul};
+use std::ops::{Add, Div, Mul, Sub};
 
 use num::Float;
 
+use crate::image::Pixel;
+
 #[derive(Copy, Clone, Default, Debug, PartialEq, Eq)]
 pub struct Vec3<T = f64> {
   pub x: T,
@@ -37,6 +39,16 @@ impl<T: Float> Vec3<T> {
   }
 }
 
+impl Vec3<f64> {
+  /// Convert into an RGB color
+  pub fn to_pixel(&self) -> Pixel {
+    let r = (self.x * 256.0) as u8;
+    let g = (self.y * 256.0) as u8;
+    let b = (self.z * 256.0) as u8;
+    Pixel(r, g, b)
+  }
+}
+
 /// Vector addition
 impl<T> Add<Vec3<T>> for Vec3<T>
 where
@@ -49,6 +61,18 @@ where
   }
 }
 
+/// Vector subtraction
+impl<T> Sub<Vec3<T>> for Vec3<T>
+where
+  T: Sub<T>,
+{
+  type Output = Vec3<T::Output>;
+
+  fn sub(self, rhs: Vec3<T>) -> Self::Output {
+    Vec3::new(self.x - rhs.x, self.y - rhs.y, self.z - rhs.z)
+  }
+}
+
 /// Scalar multiplication
 impl<T, U> Mul<U> for Vec3<T>
 where
@@ -62,6 +86,19 @@ where
   }
 }
 
+/// Scalar division
+impl<T, U> Div<U> for Vec3<T>
+where
+  T: Div<U, Output = U>,
+  U: Copy,
+{
+  type Output = Vec3<U>;
+
+  fn div(self, rhs: U) -> Self::Output {
+    Vec3::new(self.x / rhs, self.y / rhs, self.z / rhs)
+  }
+}
+
 #[cfg(test)]
 mod tests {
   use super::Vec3;

assignment-1/src/view.rs

@@ -8,6 +8,4 @@ pub struct Rect {
   pub lower_right: Vec3,
 }
 
-pub fn compute_viewing_rect() {
-
-}
+pub fn compute_viewing_rect() {}