Renderer 2, now with 100% less threading tools

I've rewritten the renderer to see if I can make a better model the
second time around. I was having a rough time untangling parts and
refactoring it piece-by-piece.

Next is to hook up the new rendering parts into a single-threaded
build. Once the parts work again, I can look into thread pooling
machinery.

src/main.rs

@@ -1,7 +1,7 @@
 
 mod primitives;
-mod renderer;
 mod scene;
+mod renderer;
 
 use crate::primitives::Vec3;
 use crate::scene::{
@@ -46,11 +46,11 @@ fn main() {
     // Iterate lines, submitting them as tasks to the thread.
 	println!("P3\n{} {}\n255", image.0, image.1);
     let context = renderer::RenderContext {
-        camera: cam,
+        camera: &scene.camera,
         image,
         max_depth,
         samples_per_pixel,
-        world,
+        world: scene.world,
     };
 
     thread::scope(|s| {

src/primitives.rs

@@ -17,6 +17,96 @@ use rand::Rng;
 use rand::rngs::SmallRng;
 use rand::distributions::Uniform;
 
+pub type Vec2i = Vec2<i32>;
+pub type Vec2f = Vec2<f32>;
+
+#[derive (Clone, Copy, PartialEq, PartialOrd, Debug)]
+pub struct Vec2<T>{
+    pub x: T,
+    pub y: T,
+}
+
+
+impl Vec2<f32> {
+    pub fn zero() -> Vec2<f32> {
+        Vec2{ x: 0.0, y: 0.0 }
+    }
+
+    pub fn ones() -> Vec2<f32> {
+        Vec2{ x: 1.0, y: 1.0 }
+    }
+
+    pub fn rand(srng: &mut SmallRng, distrib: Uniform<f32>) -> Vec2<f32> {
+        Vec2 { x: srng.sample(distrib), y: srng.sample(distrib) }
+    }
+
+}
+
+impl <T> Vec2<T> 
+where T: std::ops::Mul{
+    pub fn new(x: T, y: T) -> Vec2<T> {
+        Vec2{x, y}
+    }
+}
+
+impl <T> Add for Vec2 <T>
+where T: std::ops::Add<Output = T>{
+    type Output = Vec2<T>;
+    fn add(self, other: Vec2<T>) -> Vec2<T> {
+        Vec2 { x: self.x + other.x, y: self.y + other.y }
+    }
+}
+
+impl <T> Mul for Vec2<T> 
+where T: std::ops::Mul<Output = T>{
+    type Output = Vec2<T>;
+    fn mul(self, other: Vec2<T>) -> Vec2<T> {
+        Vec2 {
+            x: self.x * other.x,
+            y: self.y * other.y
+        }
+    }
+}
+
+impl Div<f32> for Vec2<f32>{
+    type Output = Vec2<f32>;
+    fn div(self, other: f32) -> Vec2<f32> {
+        Vec2 {
+            x: 1.0/other * self.x,
+            y: 1.0/other * self.y
+        }
+    }
+}
+
+impl Div<i32> for Vec2<i32>{
+    type Output = Vec2<i32>;
+    fn div(self, other: i32) -> Vec2<i32> {
+        Vec2 {
+            x: self.x / other,
+            y: self.y / other
+        }
+    }
+}
+
+impl <T> Div<Vec2<T>> for Vec2<T> 
+where T: std::ops::Div<Output = T>{
+    type Output = Vec2<T>;
+    fn div(self, other: Vec2<T>) -> Vec2<T> {
+        Vec2 {
+            x: self.x / other.x,
+            y: self.y / other.y
+        }
+    }
+}
+
+impl <T> Display for Vec2<T> 
+where T: Display { // nested type still needs to have Display
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let str = format!("{} {}", self.x, self.y);
+        fmt.write_str(&str)
+    }
+}
+
 #[derive(Copy, Clone, PartialEq, PartialOrd, Debug)]
 pub struct Vec3{
 	pub x: f32,
@@ -308,6 +398,22 @@ pub struct Rect {
     pub h: i32,
 }
 
+impl Rect{
+    pub fn pos(&self) -> Vec2i {
+        Vec2i {
+            x: self.x,
+            y: self.y, 
+        }
+    }
+
+    pub fn size(&self) -> Vec2i {
+        Vec2i {
+            x: self.w - self.x,
+            y: self.h - self.y,
+        }
+    }
+}
+
 #[cfg(test)]
 mod test{
     use super::*;

src/renderer.rs

@@ -1,270 +1,121 @@
 
-use crate::primitives::{Vec3, Ray, Rect};
+use crate::primitives::{
+    Vec2i,
+    Vec2f,
+    Vec3,
+    Ray,
+    Rect,
+};
 use crate::scene::{
-    Camera,
     Hittable,
+    Scene,
 };
 
-use core::cmp::Ordering;
-use std::thread;
-use std::sync::mpsc;
-use std::ops;
-use rand::Rng;
 use rand::rngs::SmallRng;
 use rand::distributions::Uniform;
-use itertools::Itertools;
 
-// =================
+const SKY_COLOR: Vec3 = Vec3 { x: 0.5, y: 0.7, z: 1.0};
-// Description parts
-// =================
 
-#[derive (Clone)]
+struct Distrs{
-pub struct RenderContext{
+    zero_one: Uniform<f32>,
-    pub image: (i32, i32),
+    one_one: Uniform<f32>,
-    pub samples_per_pixel: u32,
-    pub max_depth: u32,
-    pub world: Hittable,
-    pub camera: Camera,
 }
 
-pub struct DistributionContianer {
+struct RenderProperties {
-    pub distrib_zero_one: Uniform<f32>,
+    samples: u32, // samples are averaged results over a pixel
-    pub distrib_plusminus_one: Uniform<f32>,
+    bounces: u32, // bounces are how far the ray will travel (in hits not total distance)
 }
 
-impl DistributionContianer {
+fn to_uv(coord: Vec2i, img_size: Vec2i) -> Vec2f {
-    fn new() -> Self {
+    let u = (coord.x as f32) / ((img_size.x - 1) as f32);
-        DistributionContianer {
+    let v = (coord.y as f32) / ((img_size.y - 1) as f32);
-            distrib_zero_one: Uniform::new(0.0, 1.0),
+    Vec2f::new(u, v)
-            distrib_plusminus_one: Uniform::new(-1.0, 1.0),
-        }
-    }
 }
 
-// =============
+fn ray_color(
-// Drawing Parts
+    r: Ray, surface: &Hittable, depth: u32,
-// =============
+    rng: &mut SmallRng,
-
+    distr: &Distrs,
-fn render_line(y: i32, small_rng: &mut SmallRng, context: RenderContext, distr: &DistributionContianer) -> Vec<Vec3> {
+) -> Vec3 {
-    //TODO: Ensure that the compiler hoists the distribution's out as constants
+    // recursion guard
-    // else, do so manually
-   (0..context.image.0).map(|x| {
-       sample_pixel(x, y, small_rng, &context, distr)
-    }).collect()
-}
-
-fn ray_color(r: Ray, world: &Hittable, depth: u32, srng: &mut SmallRng, distrib: Uniform<f32> ) -> Vec3 {
-    // recursion depth guard
     if depth == 0 {
         return Vec3::zero();
     }
     
-    if let Some(rec) = world.hit(r, 0.001, f32::INFINITY){
+    // cast a ray, interrogate hit record
+    if let Some(record) = surface.hit(r, 0.001, f32::INFINITY){
         let mut scattered = Ray {
             orig: Vec3::zero(),
-            dir: Vec3::zero()
+            dir: Vec3::zero(),
         };
         let mut attenuation = Vec3::zero();
-        if rec.material.scatter(r, &rec, &mut attenuation, &mut scattered, srng) {
+        if record.material.scatter(
-            return attenuation * ray_color(scattered, world, depth-1, srng, distrib);
+            r,
-        };
+            &record,
-    }
+            &mut attenuation,
+            &mut scattered,
+            rng
+        ) {
+            return attenuation * ray_color(
+                scattered, surface, depth-1, rng, distr
+            );
+        }
+    } // TODO: explicit else block
+    // Rust gets angry about the inner if{} block because it evaluates to ()
+    // when the else path is taken. This is a problem for a function
+    // that returns Vec3 and not ().
 
-    let unitdir = Vec3::as_unit(r.dir);
+    { // when nothing is struck, return sky color
-    let t = 0.5 * (unitdir.y + 1.0);
+        let unitdir = Vec3::as_unit(r.dir);
-    return Vec3::ones() * (1.0 - t) + Vec3::new(0.5, 0.7, 1.0) * t
+        let t = 0.5 * (unitdir.y + 1.0);
+        return Vec3::ones() * (1.0 - t) + SKY_COLOR * t
+    }
 }
 
-fn sample_pixel(x: i32, y: i32, small_rng: &mut SmallRng, context: &RenderContext, distr: &DistributionContianer) -> Vec3{
+fn sample_pixel(
-    (0..context.samples_per_pixel).into_iter().fold(
+    coord: Vec2i, // location in image/screen space
+    scene: &Scene,  // scene we're drawing
+    render_props: &RenderProperties,
+    img_size: Vec2i,
+    // Supplied by the execution environment (the thread)
+    rng: &mut SmallRng,
+    dist: &Distrs,
+) -> Vec3{
+    (0..render_props.samples)
+    .fold(
         Vec3::zero(),
-        |color, _sample| {
+        |color, _sample| -> Vec3 {
-            let u = ((x as f32) + small_rng.sample(distr.distrib_zero_one)) / ((context.image.0 - 1) as f32);
+            let uv = to_uv(coord, img_size);
-            let v = ((y as f32) + small_rng.sample(distr.distrib_zero_one)) / ((context.image.1 - 1) as f32);
+            let ray = scene.camera.get_ray(uv.x, uv.y, rng);
-            let ray = context.camera.get_ray(u, v, small_rng);
+            color + ray_color(ray, &scene.world, render_props.bounces, rng, dist)
-            color + ray_color(ray, &context.world, context.max_depth, small_rng, distr.distrib_plusminus_one)
         }
     )
 }
 
-// ===============
-// Execution parts
-// ===============
-
-/* Iterable that produces pixels left-to-right, top-to-bottom.
- * `Tile`s represent the render space, not the finished image.
- * There is no internal pixel buffer
- */
-
-type TileCursorIter = itertools::Product<ops::Range<i32>, ops::Range<i32>>;
-
 struct Tile {
     bounds: Rect,
-    context: RenderContext,
+    pixels: Vec<Vec3>,
-    small_rng: SmallRng,
-    rand_distr: DistributionContianer,
-    cursor: TileCursorIter,
 }
 
-impl Tile{
+impl Tile {
-    fn new(
+    pub fn render_line(
-        bounds: Rect,
+        bounds: Rect, y: i32, // bounding rect and line
-        context: RenderContext,
+        scene: &Scene,
-        small_rng: SmallRng,
+        properties: &RenderProperties,
-        rand_distr: DistributionContianer
+        rng: &mut SmallRng, distr: &Distrs // rng utils
-    ) -> Self
+    ) -> Self {
-    {
+        let pixels = (0..bounds.w)
-        Tile { bounds, context, small_rng, rand_distr,
+        .map ( |x| -> Vec3{
-            cursor: (bounds.x..(bounds.x + bounds.w))
+            sample_pixel(
-                .cartesian_product(bounds.y..(bounds.y + bounds.h)
+                Vec2i{x, y},
+                scene,
+                properties,
+                bounds.size(),
+                rng,
+                distr
             )
-        }
+        })
-
+        .collect();
+        Self { bounds, pixels }
     }
 }
-
-impl Iterator for Tile {
-    type Item = Vec3;
-    fn next(&mut self) -> Option<Self::Item> {
-        if let Some((x, y)) = self.cursor.next(){
-            Some(sample_pixel(
-                x, y,
-                &mut self.small_rng,
-                &self.context,
-                &self.rand_distr,
-            ))
-        } else {
-            None
-        }
-    }
-}
-
-
-
-#[derive (Clone)]
-pub enum RenderCommand{
-    Stop,
-    Line { line_num: i32, context: RenderContext },
-}
-
-pub struct RenderResult {
-    pub line_num: i32,
-    pub line: Vec<Vec3>,
-}
-
-impl Ord for RenderResult {
-    fn cmp(&self, other: &Self) -> Ordering {
-        if self.line_num > other.line_num {
-            Ordering::Less
-        } else if self.line_num < other.line_num {
-            Ordering::Greater
-        } else {
-            Ordering::Equal
-        }
-    }
-}
-
-impl PartialOrd for RenderResult {
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl PartialEq for RenderResult {
-    fn eq(&self, other: &Self) -> bool {
-        self.line_num == other.line_num
-    }
-}
-
-impl Eq for RenderResult {}
-
-/*
- *  The dispatcher will hold a list of threads, and a list of command input channels to match.
- *  Helper functions exist to input jobs serially, and then dispatch them to an open thread.
- *
- *  Since receivers can be matched to several senders, the input end of the result channel will
- *  be cloned and given to each of the threads.
- *  TODO: Consider holding a copy of the render_tx end in case threads exit early and need to
- *  be restored.
- */
-pub struct Dispatcher{
-    handles: Vec<thread::JoinHandle<()>>,
-    command_transmitters: Vec<mpsc::SyncSender<RenderCommand>>, 
-    next_to_feed: usize, // gonna do a round-robin style dispatch, ig.
-}
-
-impl Dispatcher {
-    pub fn new(srng: &SmallRng, num_threads: usize) -> (Dispatcher, mpsc::Receiver<RenderResult> ) {
-        let mut handles = Vec::new();
-        let mut command_transmitters = Vec::<mpsc::SyncSender<RenderCommand>>::new();
-
-        let (render_tx, render_rx) = mpsc::sync_channel::<RenderResult>(1);
-
-        for _ in 0..num_threads {
-            // create new command tx/rx pairs. Store tx in the list, give rx to the thread.
-            let (command_tx, command_rx) = mpsc::sync_channel::<RenderCommand>(1);
-            // TODO: Pick appropriate command queue depth (or make it controllable, even)
-
-
-            let mut srng = srng.clone();
-            let threads_result_tx = render_tx.clone();
-            let distribs = DistributionContianer::new();
-            let thread_handle = thread::spawn(move || {
-                while let Ok(job) = command_rx.recv() {
-                    match job {
-                        RenderCommand::Stop => {
-                            break;
-                        }
-                        RenderCommand::Line { line_num, context } => {
-                            let line = render_line(line_num, &mut srng, context, &distribs);
-                            let result = RenderResult { line_num, line };
-                            threads_result_tx.send(result).unwrap();
-                        }
-                    }
-                }
-            });
-            handles.push(thread_handle);
-            command_transmitters.push(command_tx);
-        }
-        // finally, stash everything in the Dispatcher struct and return.
-        (
-            Dispatcher{
-                handles,
-                command_transmitters,
-                next_to_feed: 0,
-            },
-            render_rx
-        )
-    }
-
-    //TODO: Reconsider round-robin dispatch
-    // When passing the message to threads which are still busy, this function
-    // will block (it's a sync_channel). While blocked, other threads could
-    // become available and left idle.
-    pub fn submit_job(&mut self, command: RenderCommand) -> Result<(), mpsc::SendError<RenderCommand>> {
-        // Stop command is special. We'll broadcast it to all threads.
-        if let RenderCommand::Stop = command {
-            for channel in &self.command_transmitters {
-                return channel.send(command.clone());
-            }
-        }
-
-        // Check that `next_to_feed` is in-bounds, and then insert.
-        // index is post-incremented with this function call.
-
-        // wrap when at length (0-indexed so last valid index is len-1)
-        if self.next_to_feed == self.handles.len() {
-            self.next_to_feed = 0;
-        } else if self.next_to_feed > self.handles.len() {
-            panic!("How the hell did a +=1 skip past the maximum allowed size?");
-        }
-
-        match self.command_transmitters.get(self.next_to_feed){
-            Some(target) => target.send(command).unwrap(),
-            None => panic!("oh god oh fuck"),
-        }
-        self.next_to_feed += 1;
-        Ok(())
-    }
-}
-

src/scene.rs

@@ -169,7 +169,6 @@ pub fn degrees_to_radians(degrees: f32) -> f32 {
     degrees * std::f32::consts::PI / 180.0
 }
 
-#[derive (Clone, Copy)]
 pub struct Camera {
     origin: Vec3,
     lower_left_corner: Vec3,