eoc2: print filename before saving.

rtchallenge/Cargo.lock

@@ -1,5 +1,160 @@
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 # It is not intended for manual editing.
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+
 [[package]]
 name = "rtchallenge"
 version = "0.1.0"
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+ "anyhow",
+ "float-cmp",
+ "png",
+ "thiserror",
+]
+
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rtchallenge/Cargo.toml

@@ -7,3 +7,7 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+anyhow = "1.0.41"
+float-cmp = "0.8.0"
+png = "0.16.8"
+thiserror = "1.0.25"

rtchallenge/examples/eoc1.rs

@@ -0,0 +1,39 @@
+use rtchallenge::tuples::{point, vector, Tuple};
+
+#[derive(Debug)]
+struct Environment {
+    gravity: Tuple,
+    wind: Tuple,
+}
+#[derive(Debug)]
+struct Projectile {
+    position: Tuple,
+    velocity: Tuple,
+}
+
+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 p = Projectile {
+        position: point(0., 1., 0.),
+        velocity: 4. * vector(1., 1., 0.).normalize(),
+    };
+    let e = Environment {
+        gravity: vector(0., -0.1, 0.).normalize(),
+        wind: vector(-0.01, 0., 0.),
+    };
+
+    let mut i = 0;
+    while p.position.y > 0. {
+        p = tick(&e, &p);
+        println!("tick {}: position {:?}", i, p.position);
+        i += 1;
+        if i > 100 {
+            eprintln!("too many iterations");
+            return;
+        }
+    }
+}

rtchallenge/examples/eoc2.rs

@@ -0,0 +1,71 @@
+use anyhow::{bail, Result};
+
+use rtchallenge::{
+    canvas::{canvas, Canvas},
+    tuples::{color, point, vector, Tuple},
+};
+
+#[derive(Debug)]
+struct Environment {
+    gravity: Tuple,
+    wind: Tuple,
+}
+#[derive(Debug)]
+struct Projectile {
+    position: Tuple,
+    velocity: Tuple,
+}
+
+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 draw_dot(c: &mut Canvas, x: usize, y: usize) {
+    let red = color(1., 0., 0.);
+    c.set(x.saturating_sub(1), y.saturating_sub(1), red);
+    c.set(x, y.saturating_sub(1), red);
+    c.set(x + 1, y.saturating_sub(1), red);
+    c.set(x.saturating_sub(1), y, red);
+    c.set(x, y, red);
+    c.set(x + 1, y, red);
+    c.set(x.saturating_sub(1), y + 1, red);
+    c.set(x, y + 1, red);
+    c.set(x + 1, y + 1, red);
+}
+fn main() -> Result<()> {
+    let position = point(0., 1., 0.);
+    let velocity = vector(1., 1.8, 0.).normalize() * 11.25;
+    let mut p = Projectile { position, velocity };
+    let gravity = vector(0., -0.1, 0.);
+    let wind = vector(-0.01, 0., 0.);
+    let e = Environment { gravity, wind };
+
+    let w = 800;
+    let h = 600;
+    let mut c = canvas(w, h);
+    let mut i = 0;
+    let w = w as f32;
+    let h = h as f32;
+    while p.position.y > 0. {
+        p = tick(&e, &p);
+        println!("tick {}: proj {:?}", i, p);
+        let x = p.position.x;
+        let y = p.position.y;
+        if x > 0. && x < w && y > 0. && y < h {
+            let x = x as usize;
+            let y = (h - y) as usize;
+            draw_dot(&mut c, x, y)
+        }
+        i += 1;
+        if i > 1000 {
+            bail!("too many iterations");
+        }
+    }
+
+    let path = "/tmp/output.png";
+    println!("saving output to {}", path);
+    c.write_to_file(path)?;
+    Ok(())
+}

rtchallenge/src/canvas.rs

@@ -0,0 +1,97 @@
+use std::fs::File;
+use std::io::BufWriter;
+use std::path::Path;
+
+use png;
+use thiserror::Error;
+
+use crate::tuples::{color, Color};
+
+#[derive(Error, Debug)]
+pub enum CanvasError {
+    #[error("faile to write canvas")]
+    IOError(#[from] std::io::Error),
+    #[error("faile to encode canvas to png")]
+    EncodingError(#[from] png::EncodingError),
+}
+pub struct Canvas {
+    pub height: usize,
+    pub width: usize,
+    pub pixels: Vec<Color>,
+}
+
+pub fn canvas(width: usize, height: usize) -> Canvas {
+    let pixels = vec![color(0., 0., 0.); width * height];
+    Canvas {
+        width,
+        height,
+        pixels,
+    }
+}
+
+impl Canvas {
+    pub fn set(&mut self, x: usize, y: usize, c: Color) {
+        if x > self.width {
+            return;
+        }
+        if y > self.height {
+            return;
+        }
+        self.pixels[x + y * self.width] = c;
+    }
+    pub fn get(&mut self, x: usize, y: usize) -> Color {
+        self.pixels[x + y * self.width]
+    }
+    pub fn write_to_file<P>(&self, path: P) -> Result<(), CanvasError>
+    where
+        P: AsRef<Path>,
+    {
+        let path = Path::new(path.as_ref());
+        let file = File::create(path)?;
+        let ref mut w = BufWriter::new(file);
+
+        let mut encoder = png::Encoder::new(w, self.width as u32, self.height as u32);
+        encoder.set_color(png::ColorType::RGB);
+        encoder.set_depth(png::BitDepth::Eight);
+        let mut writer = encoder.write_header()?;
+
+        let data: Vec<u8> = self
+            .pixels
+            .iter()
+            .flat_map(|p| {
+                vec![
+                    (p.red.clamp(0., 1.) * 255.) as u8,
+                    (p.green.clamp(0., 1.) * 255.) as u8,
+                    (p.blue.clamp(0., 1.) * 255.) as u8,
+                ]
+            })
+            .collect();
+        writer.write_image_data(&data)?;
+        Ok(())
+    }
+}
+#[cfg(test)]
+mod tests {
+    use super::canvas;
+
+    use crate::tuples::color;
+
+    #[test]
+    fn create_canvas() {
+        let c = canvas(10, 20);
+        assert_eq!(c.width, 10);
+        assert_eq!(c.height, 20);
+        let black = color(0., 0., 0.);
+        for (i, p) in c.pixels.iter().enumerate() {
+            assert_eq!(p, &black, "pixel {} not {:?}: {:?}", i, &black, p);
+        }
+    }
+
+    #[test]
+    fn write_to_canvas() {
+        let mut c = canvas(10, 20);
+        let red = color(1., 0., 0.);
+        c.set(2, 3, red);
+        assert_eq!(c.get(2, 3), red);
+    }
+}

rtchallenge/src/lib.rs

@@ -1 +1,2 @@
-mod tuples;
+pub mod canvas;
+pub mod tuples;

rtchallenge/src/tuples.rs

@@ -1,36 +1,218 @@
-#[derive(Debug, PartialEq)]
-struct Tuple {
-    x: f32,
-    y: f32,
-    z: f32,
-    w: f32,
+use std::ops::{Add, Div, Mul, Neg, Sub};
+#[derive(Debug, PartialEq, Copy, Clone)]
+pub struct Tuple {
+    pub x: f32,
+    pub y: f32,
+    pub z: f32,
+    pub w: f32,
 }
 
 impl Tuple {
-    fn is_point(&self) -> bool {
+    pub fn is_point(&self) -> bool {
         self.w == 1.0
     }
 
-    fn is_vector(&self) -> bool {
+    pub fn is_vector(&self) -> bool {
         self.w == 0.0
     }
+
+    pub fn magnitude(&self) -> f32 {
+        (self.x * self.x + self.y * self.y + self.z * self.z + self.w * self.w).sqrt()
+    }
+    pub fn normalize(&self) -> Tuple {
+        let m = self.magnitude();
+        Tuple {
+            x: self.x / m,
+            y: self.y / m,
+            z: self.z / m,
+            w: self.w / m,
+        }
+    }
 }
 
-fn point(x: f32, y: f32, z: f32) -> Tuple {
+impl Add for Tuple {
+    type Output = Self;
+    fn add(self, other: Self) -> Self {
+        Self {
+            x: self.x + other.x,
+            y: self.y + other.y,
+            z: self.z + other.z,
+            w: self.w + other.w,
+        }
+    }
+}
+
+impl Div<f32> for Tuple {
+    type Output = Self;
+    fn div(self, rhs: f32) -> Self::Output {
+        Self::Output {
+            x: self.x / rhs,
+            y: self.y / rhs,
+            z: self.z / rhs,
+            w: self.w / rhs,
+        }
+    }
+}
+
+impl Mul<f32> for Tuple {
+    type Output = Self;
+    fn mul(self, rhs: f32) -> Self::Output {
+        Self::Output {
+            x: self.x * rhs,
+            y: self.y * rhs,
+            z: self.z * rhs,
+            w: self.w * rhs,
+        }
+    }
+}
+
+impl Mul<Tuple> for f32 {
+    type Output = Tuple;
+    fn mul(self, rhs: Tuple) -> Self::Output {
+        Self::Output {
+            x: self * rhs.x,
+            y: self * rhs.y,
+            z: self * rhs.z,
+            w: self * rhs.w,
+        }
+    }
+}
+
+impl Neg for Tuple {
+    type Output = Self;
+    fn neg(self) -> Self::Output {
+        Self {
+            x: -self.x,
+            y: -self.y,
+            z: -self.z,
+            w: -self.w,
+        }
+    }
+}
+impl Sub for Tuple {
+    type Output = Self;
+    fn sub(self, other: Self) -> Self {
+        Self {
+            x: self.x - other.x,
+            y: self.y - other.y,
+            z: self.z - other.z,
+            w: self.w - other.w,
+        }
+    }
+}
+
+pub fn point(x: f32, y: f32, z: f32) -> Tuple {
     tuple(x, y, z, 1.0)
 }
 
-fn vector(x: f32, y: f32, z: f32) -> Tuple {
+pub fn vector(x: f32, y: f32, z: f32) -> Tuple {
     tuple(x, y, z, 0.0)
 }
 
-fn tuple(x: f32, y: f32, z: f32, w: f32) -> Tuple {
+pub fn tuple(x: f32, y: f32, z: f32, w: f32) -> Tuple {
     Tuple { x, y, z, w }
 }
 
+pub fn dot(a: Tuple, b: Tuple) -> f32 {
+    a.x * b.x + a.y * b.y + a.z * b.z + a.w * b.w
+}
+pub fn cross(a: Tuple, b: Tuple) -> Tuple {
+    vector(
+        a.y * b.z - a.z * b.y,
+        a.z * b.x - a.x * b.z,
+        a.x * b.y - a.y * b.x,
+    )
+}
+
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub struct Color {
+    pub red: f32,
+    pub green: f32,
+    pub blue: f32,
+}
+pub fn color(red: f32, green: f32, blue: f32) -> Color {
+    Color { red, green, blue }
+}
+impl Add for Color {
+    type Output = Self;
+    fn add(self, other: Self) -> Self {
+        Self {
+            red: self.red + other.red,
+            green: self.green + other.green,
+            blue: self.blue + other.blue,
+        }
+    }
+}
+
+impl Div<f32> for Color {
+    type Output = Self;
+    fn div(self, rhs: f32) -> Self::Output {
+        Self::Output {
+            red: self.red / rhs,
+            green: self.green / rhs,
+            blue: self.blue / rhs,
+        }
+    }
+}
+
+impl Mul<f32> for Color {
+    type Output = Self;
+    fn mul(self, rhs: f32) -> Self::Output {
+        Self::Output {
+            red: self.red * rhs,
+            green: self.green * rhs,
+            blue: self.blue * rhs,
+        }
+    }
+}
+
+impl Mul<Color> for f32 {
+    type Output = Color;
+    fn mul(self, rhs: Color) -> Self::Output {
+        Self::Output {
+            red: self * rhs.red,
+            green: self * rhs.green,
+            blue: self * rhs.blue,
+        }
+    }
+}
+impl Mul<Color> for Color {
+    type Output = Color;
+    fn mul(self, rhs: Color) -> Self::Output {
+        Self::Output {
+            red: self.red * rhs.red,
+            green: self.green * rhs.green,
+            blue: self.blue * rhs.blue,
+        }
+    }
+}
+
+impl Neg for Color {
+    type Output = Self;
+    fn neg(self) -> Self::Output {
+        Self {
+            red: -self.red,
+            green: -self.green,
+            blue: -self.blue,
+        }
+    }
+}
+impl Sub for Color {
+    type Output = Self;
+    fn sub(self, other: Self) -> Self {
+        Self {
+            red: self.red - other.red,
+            green: self.green - other.green,
+            blue: self.blue - other.blue,
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
-    use super::{point, tuple, vector};
+    use float_cmp::approx_eq;
+
+    use super::{color, cross, dot, point, tuple, vector};
     #[test]
     fn is_point() {
         // A tuple with w = 1 is a point
@@ -61,4 +243,126 @@ mod tests {
     fn vector_tuple() {
         assert_eq!(vector(4., -4., 3.), tuple(4., -4., 3., 0.))
     }
+    #[test]
+    fn add_two_tuples() {
+        let a1 = tuple(3., -2., 5., 1.);
+        let a2 = tuple(-2., 3., 1., 0.);
+        assert_eq!(a1 + a2, tuple(1., 1., 6., 1.));
+    }
+    #[test]
+    fn sub_two_points() {
+        let p1 = point(3., 2., 1.);
+        let p2 = point(5., 6., 7.);
+        assert_eq!(p1 - p2, vector(-2., -4., -6.));
+    }
+    #[test]
+    fn sub_vector_point() {
+        let p = point(3., 2., 1.);
+        let v = vector(5., 6., 7.);
+        assert_eq!(p - v, point(-2., -4., -6.));
+    }
+    #[test]
+    fn sub_two_vectors() {
+        let v1 = vector(3., 2., 1.);
+        let v2 = vector(5., 6., 7.);
+        assert_eq!(v1 - v2, vector(-2., -4., -6.));
+    }
+    #[test]
+    fn sub_zero_vector() {
+        let zero = vector(0., 0., 0.);
+        let v = vector(1., -2., 3.);
+        assert_eq!(zero - v, vector(-1., 2., -3.));
+    }
+    #[test]
+    fn negate_tuple() {
+        let a = tuple(1., -2., 3., -4.);
+        assert_eq!(-a, tuple(-1., 2., -3., 4.));
+    }
+    #[test]
+    fn mul_tuple_scalar() {
+        let a = tuple(1., -2., 3., -4.);
+        assert_eq!(a * 3.5, tuple(3.5, -7., 10.5, -14.));
+        assert_eq!(3.5 * a, tuple(3.5, -7., 10.5, -14.));
+    }
+    #[test]
+    fn mul_tuple_fraction() {
+        let a = tuple(1., -2., 3., -4.);
+        assert_eq!(a * 0.5, tuple(0.5, -1., 1.5, -2.));
+        assert_eq!(0.5 * a, tuple(0.5, -1., 1.5, -2.));
+    }
+    #[test]
+    fn div_tuple_scalar() {
+        let a = tuple(1., -2., 3., -4.);
+        assert_eq!(a / 2., tuple(0.5, -1., 1.5, -2.));
+    }
+    #[test]
+    fn vector_magnitude() {
+        assert_eq!(1., vector(1., 0., 0.).magnitude());
+        assert_eq!(1., vector(0., 1., 0.).magnitude());
+        assert_eq!(1., vector(0., 0., 1.).magnitude());
+        assert_eq!(14_f32.sqrt(), vector(1., 2., 3.).magnitude());
+        assert_eq!(14_f32.sqrt(), vector(-1., -2., -3.).magnitude());
+    }
+    #[test]
+    fn vector_normalize() {
+        assert_eq!(vector(1., 0., 0.), vector(4., 0., 0.).normalize());
+        assert_eq!(
+            vector(1. / 14_f32.sqrt(), 2. / 14_f32.sqrt(), 3. / 14_f32.sqrt()),
+            vector(1., 2., 3.).normalize()
+        );
+    }
+    #[test]
+    fn vector_normalize_magnitude() {
+        assert!(approx_eq!(
+            f32,
+            1.,
+            vector(1., 2., 3.).normalize().magnitude(),
+            ulps = 1
+        ));
+    }
+    #[test]
+    fn dot_two_tuples() {
+        let a = vector(1., 2., 3.);
+        let b = vector(2., 3., 4.);
+        assert_eq!(20., dot(a, b));
+    }
+    #[test]
+    fn cross_two_tuples() {
+        let a = vector(1., 2., 3.);
+        let b = vector(2., 3., 4.);
+        assert_eq!(vector(-1., 2., -1.), cross(a, b));
+        assert_eq!(vector(1., -2., 1.), cross(b, a));
+    }
+
+    #[test]
+    fn color_rgb() {
+        let c = color(-0.5, 0.4, 1.7);
+        assert_eq!(c.red, -0.5);
+        assert_eq!(c.green, 0.4);
+        assert_eq!(c.blue, 1.7);
+    }
+    #[test]
+    fn add_color() {
+        let c1 = color(0.9, 0.6, 0.75);
+        let c2 = color(0.7, 0.1, 0.25);
+        assert_eq!(c1 + c2, color(0.9 + 0.7, 0.6 + 0.1, 0.75 + 0.25));
+    }
+    #[test]
+    fn sub_color() {
+        let c1 = color(0.9, 0.6, 0.75);
+        let c2 = color(0.7, 0.1, 0.25);
+        assert_eq!(c1 - c2, color(0.9 - 0.7, 0.6 - 0.1, 0.75 - 0.25));
+    }
+    #[test]
+    fn mul_color_scalar() {
+        let c = color(0.2, 0.3, 0.4);
+        assert_eq!(c * 2., color(0.2 * 2., 0.3 * 2., 0.4 * 2.));
+        assert_eq!(2. * c, color(0.2 * 2., 0.3 * 2., 0.4 * 2.));
+    }
+    #[test]
+    fn mul_colors() {
+        let c1 = color(1., 0.2, 0.4);
+        let c2 = color(0.9, 1., 0.1);
+        assert_eq!(c1 * c2, color(1.0 * 0.9, 0.2 * 1., 0.4 * 0.1));
+    }
 }