Finish PPM conversions and plot the projectile

This helps out when I go to use the same data structure as the backing
for colors.

Cargo.lock

@@ -3331,6 +3331,10 @@ dependencies = [
  "rand_core 0.6.4",
 ]
 
+[[package]]
+name = "ray-tracer"
+version = "0.1.0"
+
 [[package]]
 name = "rayon"
 version = "1.8.0"

Cargo.toml

@@ -27,5 +27,5 @@ members = [
     "sgf",
     "timezone-testing",
     "tree",
-    "visions/server",
+    "visions/server", "ray-tracer",
 ]

ray-tracer/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "ray-tracer"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+
+[[bin]]
+name = "projectile"

ray-tracer/src/bin/projectile.rs

@@ -0,0 +1,53 @@
+use ray_tracer::{types::*, PPM};
+use std::{fs::File, io::Write};
+
+#[derive(Clone, Copy)]
+struct Projectile {
+    position: Point,
+    velocity: Vector,
+}
+
+struct Environment {
+    gravity: Vector,
+    wind: Vector,
+}
+
+fn tick(env: &Environment, proj: &Projectile) -> Projectile {
+    let position = proj.position + proj.velocity;
+    let velocity = proj.velocity + env.gravity + env.wind;
+    Projectile { position, velocity }
+}
+
+fn main() {
+    let mut canvas = Canvas::new(900, 550);
+
+    let start = Projectile {
+        position: Point::new(0., 1., 0.),
+        velocity: Vector::new(1., 5., 0.).normalize() * 5.,
+    };
+
+    let e = Environment {
+        gravity: Vector::new(0., -0.1, 0.),
+        wind: Vector::new(-0.01, 0., 0.),
+    };
+
+    let mut p = start;
+    while p.position.y() > 0. {
+        p = tick(&e, &p);
+
+        let x = p.position.x().round() as usize;
+        let y = p.position.y().round() as usize;
+        if x > 1 && x < 900 && y > 1 && y < 550 {
+            *canvas.pixel_mut(x, 550 - y - 1) = Color::new(1., 1., 0.);
+            *canvas.pixel_mut(x+1, 550 - y - 1) = Color::new(1., 1., 0.);
+            *canvas.pixel_mut(x-1, 550 - y - 1) = Color::new(1., 1., 0.);
+            *canvas.pixel_mut(x, 550 - y) = Color::new(1., 1., 0.);
+            *canvas.pixel_mut(x, 550 - y - 2) = Color::new(1., 1., 0.);
+        }
+    }
+
+    let ppm = PPM::from(canvas);
+
+    let mut file = File::create("projectile.ppm").unwrap();
+    file.write(ppm.as_bytes()).unwrap();
+}

ray-tracer/src/lib.rs

@@ -0,0 +1,5 @@
+mod ppm;
+
+pub mod types;
+
+pub use ppm::PPM;

ray-tracer/src/ppm.rs

@@ -0,0 +1,119 @@
+use crate::types::Canvas;
+
+fn color_float_to_int(val: f64) -> u8 {
+    (val * 256.).clamp(0., 255.) as u8
+}
+
+fn join_to_line_limit(data: impl IntoIterator<Item = String>) -> Vec<String> {
+    let mut lines = vec![];
+
+    let mut line = String::new();
+    let mut iter = data.into_iter();
+    while let Some(element) = iter.next() {
+        if line.is_empty() {
+            line = line + &element;
+        } else if line.len() + 1 + element.len() < 70 {
+            line = line + " " + &element;
+        } else {
+            lines.push(line);
+            line = element;
+        }
+    }
+
+    if !line.is_empty() {
+        lines.push(line);
+    }
+
+    lines
+}
+
+#[derive(Debug)]
+pub struct PPM(String);
+
+impl From<Canvas> for PPM {
+    fn from(c: Canvas) -> Self {
+        // let v = vec![0.; c.width() * c.height() * 3];
+        let header = format!("P3\n{} {}\n255\n", c.width(), c.height());
+
+        let mut data = vec![];
+        for y in 0..c.height() {
+            let mut row = vec![];
+            for x in 0..c.width() {
+                let pixel = c.pixel(x, y);
+                row.push(color_float_to_int(pixel.red()).to_string());
+                row.push(color_float_to_int(pixel.green()).to_string());
+                row.push(color_float_to_int(pixel.blue()).to_string());
+            }
+            let mut lines = join_to_line_limit(row);
+            data.append(&mut lines);
+        }
+
+        let data = data.join("\n");
+
+        Self(format!("{header}{data}\n"))
+    }
+}
+
+impl std::ops::Deref for PPM {
+    type Target = String;
+    fn deref(&self) -> &String {
+        &self.0
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::types::Color;
+
+    #[test]
+    fn construct_ppm_header() {
+        let c = Canvas::new(5, 3);
+        let ppm = PPM::from(c);
+
+        assert!(ppm.starts_with(
+            "P3\n\
+                5 3\n\
+                255\n"
+        ));
+    }
+
+    #[test]
+    fn construct_full_ppm_data() {
+        let mut c = Canvas::new(5, 3);
+        *c.pixel_mut(0, 0) = Color::new(1.5, 0., 0.);
+        *c.pixel_mut(2, 1) = Color::new(0., 0.5, 0.);
+        *c.pixel_mut(4, 2) = Color::new(-0.5, 0., 1.);
+
+        let expected = "P3\n\
+                        5 3\n\
+                        255\n\
+                        255 0 0 0 0 0 0 0 0 0 0 0 0 0 0\n\
+                        0 0 0 0 0 0 0 128 0 0 0 0 0 0 0\n\
+                        0 0 0 0 0 0 0 0 0 0 0 0 0 0 255\n";
+
+        let ppm = PPM::from(c);
+        assert_eq!(*ppm, expected);
+    }
+
+    #[test]
+    fn ppm_line_length_limit() {
+        let mut c = Canvas::new(10, 2);
+        for y in 0..2 {
+            for x in 0..10 {
+                *c.pixel_mut(x, y) = Color::new(1., 0.8, 0.6);
+            }
+        }
+
+        let expected = "P3\n\
+                        10 2\n\
+                        255\n\
+                        255 204 153 255 204 153 255 204 153 255 204 153 255 204 153 255 204\n\
+     	                153 255 204 153 255 204 153 255 204 153 255 204 153\n\
+     	                255 204 153 255 204 153 255 204 153 255 204 153 255 204 153 255 204\n\
+     	                153 255 204 153 255 204 153 255 204 153 255 204 153\n";
+
+        let ppm = PPM::from(c);
+        assert_eq!(*ppm, expected);
+    }
+}

ray-tracer/src/types/canvas.rs

@@ -0,0 +1,59 @@
+use crate::types::Color;
+
+pub struct Canvas {
+    width: usize,
+    height: usize,
+    pixels: Vec<Color>,
+}
+
+impl Canvas {
+    pub fn new(width: usize, height: usize) -> Self {
+        Self {
+            width,
+            height,
+            pixels: vec![Color::default(); width * height],
+        }
+    }
+
+    #[inline]
+    pub fn width(&self) -> usize {
+        self.width
+    }
+
+    #[inline]
+    pub fn height(&self) -> usize {
+        self.height
+    }
+
+    pub fn pixel(&self, x: usize, y: usize) -> &Color {
+        &self.pixels[self.addr(y, x)]
+    }
+
+    pub fn pixel_mut<'a>(&'a mut self, x: usize, y: usize) -> &'a mut Color {
+        let addr = self.addr(y, x);
+        &mut self.pixels[addr]
+    }
+
+    #[inline]
+    fn addr(&self, y: usize, x: usize) -> usize {
+        let val = y * self.width() + x;
+        if val >= self.pixels.len() {
+            eprintln!("[{val}] out of range: [{x}, {y}]");
+        }
+        val
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn addresses() {
+        let c = Canvas::new(5, 3);
+
+        assert_eq!(c.addr(0, 0), 0);
+        assert_eq!(c.addr(1, 0), 5);
+        assert_eq!(c.addr(2, 0), 10);
+    }
+}

ray-tracer/src/types/color.rs

@@ -0,0 +1,87 @@
+use crate::types::Tuple;
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Color(Tuple);
+
+impl Color {
+    pub fn new(red: f64, green: f64, blue: f64) -> Self {
+        Self(Tuple(red, green, blue, 0.))
+    }
+
+    #[inline]
+    pub fn red(&self) -> f64 {
+        self.0.0
+    }
+
+    #[inline]
+    pub fn green(&self) -> f64 {
+        self.0.1
+    }
+
+    #[inline]
+    pub fn blue(&self) -> f64 {
+        self.0.2
+    }
+
+}
+
+impl Default for Color {
+    fn default() -> Self {
+        Self::new(0., 0., 0.)
+    }
+}
+
+impl From<Tuple> for Color {
+    fn from(tuple: Tuple) -> Self {
+        assert_eq!(tuple.3, 0.0);
+        Self(tuple)
+    }
+}
+
+impl std::ops::Deref for Color {
+    type Target = Tuple;
+    fn deref(&self) -> &Tuple {
+        &self.0
+    }
+}
+
+impl std::ops::Add for Color {
+    type Output = Color;
+    fn add(self, r: Self) -> Self {
+        Color::from(self.0 + r.0)
+    }
+}
+
+impl std::ops::Sub for Color {
+    type Output = Color;
+    fn sub(self, r: Self) -> Self {
+        Color::from(self.0 - r.0)
+    }
+}
+
+impl std::ops::Neg for Color {
+    type Output = Color;
+    fn neg(self) -> Self::Output {
+        let mut t = -self.0;
+        t.0 = 0.;
+        Color::from(t)
+    }
+}
+
+impl std::ops::Mul for Color {
+    type Output = Color;
+    fn mul(self, r: Color) -> Self {
+        let red = self.red() * r.red();
+        let green = self.green() * r.green();
+        let blue = self.blue() * r.blue();
+        Self::new(red, green, blue)
+    }
+}
+
+impl std::ops::Mul<f64> for Color {
+    type Output = Color;
+    fn mul(self, r: f64) -> Self {
+        Color::from(self.0 * r)
+    }
+}
+

ray-tracer/src/types/mod.rs

@@ -0,0 +1,151 @@
+mod canvas;
+mod color;
+mod point;
+mod tuple;
+mod vector;
+
+pub use canvas::Canvas;
+pub use color::Color;
+pub use point::Point;
+pub use tuple::Tuple;
+pub use vector::Vector;
+
+const EPSILON: f64 = 0.00001;
+
+fn eq_f64(l: f64, r: f64) -> bool {
+    (l - r).abs() < EPSILON
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn eq_f64_compares_values() {
+        assert!(eq_f64(1.0, 1.0));
+        assert!(eq_f64(0.9994, 0.9994));
+        assert!(eq_f64(0.9999994, 0.9999995));
+        assert!(!eq_f64(0.9995, 0.9994));
+    }
+
+    #[test]
+    fn add_two_tuples() {
+        let a = Tuple(3., -2., 5., 1.);
+        let b = Tuple(-2., 3., 1., 0.);
+        assert_eq!(a + b, Tuple(1., 1., 6., 1.));
+    }
+
+    #[test]
+    fn subtracts_two_tuples() {
+        let a = Tuple(3., 2., 1., 1.);
+        let b = Tuple(5., 6., 7., 1.);
+        assert_eq!(a - b, Tuple(-2., -4., -6., 0.));
+    }
+
+    #[test]
+    fn adds_point_and_vector() {
+        let a = Point::new(3., -2., 5.);
+        let b = Vector::new(-2., 3., 1.);
+        assert_eq!(a + b, Point::new(1., 1., 6.,));
+    }
+
+    #[test]
+    fn subtracts_two_points() {
+        let a = Point::new(3., 2., 1.);
+        let b = Point::new(5., 6., 7.);
+        assert_eq!(a - b, Vector::new(-2., -4., -6.,));
+    }
+
+    #[test]
+    fn subtracts_vector_from_point() {
+        let a = Point::new(3., 2., 1.);
+        let b = Vector::new(5., 6., 7.);
+        assert_eq!(a - b, Point::new(-2., -4., -6.));
+    }
+
+    #[test]
+    fn subtracts_two_vectors() {
+        let a = Vector::new(3., 2., 1.);
+        let b = Vector::new(5., 6., 7.);
+        assert_eq!(a - b, Vector::new(-2., -4., -6.));
+    }
+
+    #[test]
+    fn it_negates_primitives() {
+        assert_eq!(-Tuple(1., 2., 3., 4.), Tuple(-1., -2., -3., -4.),);
+    }
+
+    #[test]
+    fn multiply_tuple_by_scalar() {
+        assert_eq!(Tuple(1., -2., 3., -4.) * 3.5, Tuple(3.5, -7., 10.5, -14.));
+    }
+
+    #[test]
+    fn divide_tuple_by_scalar() {
+        assert_eq!(Tuple(1., -2., 3., -4.) / 2., Tuple(0.5, -1., 1.5, -2.));
+    }
+
+    #[test]
+    fn magnitude_of_vector() {
+        assert_eq!(Vector::new(1., 0., 0.).magnitude(), 1.);
+        assert_eq!(Vector::new(0., 1., 0.).magnitude(), 1.);
+        assert_eq!(Vector::new(0., 0., 1.).magnitude(), 1.);
+        assert_eq!(Vector::new(1., 2., 3.).magnitude(), 14_f64.sqrt());
+        assert_eq!(Vector::new(-1., -2., -3.).magnitude(), 14_f64.sqrt());
+    }
+
+    #[test]
+    fn normalize_vector() {
+        assert_eq!(Vector::new(4., 0., 0.).normalize(), Vector::new(1., 0., 0.));
+        assert_eq!(
+            Vector::new(1., 2., 3.).normalize(),
+            Vector::new(0.26726, 0.53452, 0.80178)
+        );
+        assert_eq!(Vector::new(1., 2., 3.).normalize().magnitude(), 1.);
+    }
+
+    #[test]
+    fn dot_product() {
+        assert_eq!(Vector::new(1., 2., 3.).dot(&Vector::new(2., 3., 4.)), 20.);
+    }
+
+    #[test]
+    fn cross_product() {
+        assert_eq!(
+            Vector::new(1., 2., 3.).cross(&Vector::new(2., 3., 4.)),
+            Vector::new(-1., 2., -1.)
+        );
+        assert_eq!(
+            Vector::new(2., 3., 4.).cross(&Vector::new(1., 2., 3.)),
+            Vector::new(1., -2., 1.)
+        );
+    }
+
+    #[test]
+    fn multiply_colors() {
+        let c1 = Color::new(1., 0.2, 0.4);
+        let c2 = Color::new(0.9, 1., 0.1);
+
+        assert_eq!(c1 * c2, Color::new(0.9, 0.2, 0.04));
+    }
+
+    #[test]
+    fn it_creates_a_canvas() {
+        let c = Canvas::new(10, 20);
+        assert_eq!(c.width(), 10);
+        assert_eq!(c.height(), 20);
+        for row in 0..20 {
+            for col in 0..10 {
+                assert_eq!(*c.pixel(row, col), Color::default());
+            }
+        }
+    }
+
+    #[test]
+    fn it_can_write_pixel() {
+        let mut c = Canvas::new(10, 20);
+        let red = Color::new(1., 0., 0.);
+        *c.pixel_mut(2, 3) = red;
+        assert_eq!(*c.pixel(2, 3), red);
+    }
+}

ray-tracer/src/types/point.rs

@@ -0,0 +1,75 @@
+use crate::types::{Tuple, Vector};
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Point(Tuple);
+
+impl Point {
+    pub fn new(x: f64, y: f64, z: f64) -> Self {
+        Self(Tuple(x, y, z, 1.0))
+    }
+
+    #[inline]
+    pub fn x(&self) -> f64 {
+        self.0.0
+    }
+
+    #[inline]
+    pub fn y(&self) -> f64 {
+        self.0.1
+    }
+
+    #[inline]
+    pub fn z(&self) -> f64 {
+        self.0.2
+    }
+}
+
+impl Default for Point {
+    fn default() -> Self {
+        Self::new(0., 0., 0.)
+    }
+}
+
+impl From<Tuple> for Point {
+    fn from(tuple: Tuple) -> Self {
+        assert_eq!(tuple.3, 1.0);
+        Self(tuple)
+    }
+}
+
+impl std::ops::Deref for Point {
+    type Target = Tuple;
+    fn deref(&self) -> &Tuple {
+        &self.0
+    }
+}
+
+impl std::ops::Add<Vector> for Point {
+    type Output = Point;
+    fn add(self, r: Vector) -> Self::Output {
+        Point::from(self.0 + *r)
+    }
+}
+
+impl std::ops::Sub for Point {
+    type Output = Vector;
+    fn sub(self, r: Point) -> Self::Output {
+        Vector::from(self.0 - r.0)
+    }
+}
+
+impl std::ops::Sub<Vector> for Point {
+    type Output = Point;
+    fn sub(self, r: Vector) -> Self::Output {
+        Point::from(self.0 - *r)
+    }
+}
+
+impl std::ops::Neg for Point {
+    type Output = Point;
+    fn neg(self) -> Self::Output {
+        let mut t = -self.0;
+        t.3 = 1.;
+        Point::from(t)
+    }
+}

ray-tracer/src/types/tuple.rs

@@ -0,0 +1,72 @@
+use crate::types::eq_f64;
+
+#[derive(Debug, Clone, Copy)]
+pub struct Tuple(
+    pub f64, // x or red
+    pub f64, // y or green
+    pub f64, // z or blue
+    pub f64, // w, the flag which
+         // indicates point vs vec, or alpha
+);
+
+impl Tuple {
+    pub fn dot(&self, r: &Tuple) -> f64 {
+        self.0 * r.0 + self.1 * r.1 + self.2 * r.2 + self.3 * r.3
+    }
+}
+
+impl PartialEq for Tuple {
+    fn eq(&self, r: &Tuple) -> bool {
+        eq_f64(self.0, r.0) && eq_f64(self.1, r.1) && eq_f64(self.2, r.2) && eq_f64(self.3, r.3)
+    }
+}
+
+impl std::ops::Add for Tuple {
+    type Output = Tuple;
+    fn add(self, r: Tuple) -> Self::Output {
+        Tuple(self.0 + r.0, self.1 + r.1, self.2 + r.2, self.3 + r.3)
+    }
+}
+
+impl std::ops::Sub for Tuple {
+    type Output = Tuple;
+    fn sub(self, r: Tuple) -> Self::Output {
+        Tuple(self.0 - r.0, self.1 - r.1, self.2 - r.2, self.3 - r.3)
+    }
+}
+
+impl std::ops::Neg for Tuple {
+    type Output = Tuple;
+    fn neg(self) -> Self::Output {
+        return Self::Output {
+            0: -self.0,
+            1: -self.1,
+            2: -self.2,
+            3: -self.3,
+        };
+    }
+}
+
+impl std::ops::Mul<f64> for Tuple {
+    type Output = Tuple;
+    fn mul(self, scalar: f64) -> Self::Output {
+        Tuple(
+            self.0 * scalar,
+            self.1 * scalar,
+            self.2 * scalar,
+            self.3 * scalar,
+        )
+    }
+}
+
+impl std::ops::Div<f64> for Tuple {
+    type Output = Tuple;
+    fn div(self, scalar: f64) -> Self::Output {
+        Tuple(
+            self.0 / scalar,
+            self.1 / scalar,
+            self.2 / scalar,
+            self.3 / scalar,
+        )
+    }
+}

ray-tracer/src/types/vector.rs

@@ -0,0 +1,95 @@
+use crate::types::Tuple;
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Vector(Tuple);
+
+impl Vector {
+    pub fn new(x: f64, y: f64, z: f64) -> Self {
+        Self(Tuple(x, y, z, 0.0))
+    }
+
+    #[inline]
+    pub fn x(&self) -> f64 {
+        self.0.0
+    }
+
+    #[inline]
+    pub fn y(&self) -> f64 {
+        self.0.1
+    }
+
+    #[inline]
+    pub fn z(&self) -> f64 {
+        self.0.2
+    }
+
+    pub fn magnitude(&self) -> f64 {
+        (self.x() * self.x() + self.y() * self.y() + self.z() * self.z()).sqrt()
+    }
+
+    pub fn normalize(&self) -> Self {
+        let mag = self.magnitude();
+        Self::new(self.x() / mag, self.y() / mag, self.z() / mag)
+    }
+
+    pub fn dot(&self, r: &Vector) -> f64 {
+        self.0.dot(r)
+    }
+
+    pub fn cross(&self, r: &Vector) -> Self {
+        let x = self.y() * r.z() - self.z() * r.y();
+        let y = self.z() * r.x() - self.x() * r.z();
+        let z = self.x() * r.y() - self.y() * r.x();
+        Self::new(x, y, z)
+    }
+}
+
+impl Default for Vector {
+    fn default() -> Self {
+        Self::new(0., 0., 0.)
+    }
+}
+
+impl From<Tuple> for Vector {
+    fn from(tuple: Tuple) -> Self {
+        assert_eq!(tuple.3, 0.0);
+        Self(tuple)
+    }
+}
+
+impl std::ops::Deref for Vector {
+    type Target = Tuple;
+    fn deref(&self) -> &Tuple {
+        &self.0
+    }
+}
+
+impl std::ops::Add for Vector {
+    type Output = Vector;
+    fn add(self, r: Self) -> Self {
+        Vector::from(self.0 + r.0)
+    }
+}
+
+impl std::ops::Sub for Vector {
+    type Output = Vector;
+    fn sub(self, r: Self) -> Self {
+        Vector::from(self.0 - r.0)
+    }
+}
+
+impl std::ops::Neg for Vector {
+    type Output = Vector;
+    fn neg(self) -> Self::Output {
+        let mut t = -self.0;
+        t.0 = 0.;
+        Vector::from(t)
+    }
+}
+
+impl std::ops::Mul<f64> for Vector {
+    type Output = Vector;
+    fn mul(self, r: f64) -> Self {
+        Vector::from(self.0 * r)
+    }
+}