From 14f7b47f2c2315d0de5e52d31c57fe07a15d08ad Mon Sep 17 00:00:00 2001
From: Julian T <julian@jtle.dk>
Date: Fri, 12 Feb 2021 23:33:50 +0100
Subject: Implement multithreaded compiling of tiles

---
 Cargo.lock                | 25 +++++++++++++++++++++++++
 Cargo.toml                |  1 +
 src/main.rs               | 12 ++++++------
 src/render/coordinator.rs | 14 +++++++++++++-
 src/sample/mod.rs         |  2 ++
 src/sample/uniform.rs     |  6 ++++++
 src/world/mod.rs          |  8 ++++----
 7 files changed, 57 insertions(+), 11 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index c9f49c0..370504f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -63,6 +63,20 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "crossbeam"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fd01a6eb3daaafa260f6fc94c3a6c36390abc2080e38e3e34ced87393fb77d80"
+dependencies = [
+ "cfg-if",
+ "crossbeam-channel",
+ "crossbeam-deque",
+ "crossbeam-epoch",
+ "crossbeam-queue",
+ "crossbeam-utils",
+]
+
 [[package]]
 name = "crossbeam-channel"
 version = "0.5.0"
@@ -98,6 +112,16 @@ dependencies = [
  "scopeguard",
 ]
 
+[[package]]
+name = "crossbeam-queue"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0f6cb3c7f5b8e51bc3ebb73a2327ad4abdbd119dc13223f14f961d2f38486756"
+dependencies = [
+ "cfg-if",
+ "crossbeam-utils",
+]
+
 [[package]]
 name = "crossbeam-utils"
 version = "0.8.1"
@@ -370,6 +394,7 @@ dependencies = [
 name = "rendering"
 version = "0.1.0"
 dependencies = [
+ "crossbeam",
  "image",
  "rand",
  "rand_pcg",
diff --git a/Cargo.toml b/Cargo.toml
index 09f2c2e..629e22f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,3 +10,4 @@ edition = "2018"
 image = "0.23.12"
 rand = "0.8.3"
 rand_pcg = "0.3.0"
+crossbeam = "0.8.0"
diff --git a/src/main.rs b/src/main.rs
index 215e0d4..0f6502e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -6,7 +6,7 @@ use rendering::render::{RenderContext, RenderCoord};
 use rendering::sample::UniformSampler;
 use rendering::material::{Reflectant, Lambertian};
 
-use std::rc::Rc;
+use std::sync::Arc;
 
 fn main() {
     let res = Vector2i::new_xy(500, 500);
@@ -21,9 +21,9 @@ fn main() {
         aperture: Some(20.0),
     });
 
-    let brown = Rc::new(Lambertian::new(Spectrum::new_rgb(0.5, 0.3, 0.0)));
-    let blue = Rc::new(Lambertian::new(Spectrum::new_rgb(0.0, 0.3, 0.7)));
-    let metal = Rc::new(Reflectant::new(Spectrum::new_rgb(0.75, 0.75, 0.75), None));
+    let brown = Arc::new(Lambertian::new(Spectrum::new_rgb(0.5, 0.3, 0.0)));
+    let blue = Arc::new(Lambertian::new(Spectrum::new_rgb(0.0, 0.3, 0.7)));
+    let metal = Arc::new(Reflectant::new(Spectrum::new_rgb(0.75, 0.75, 0.75), None));
 
     let mut scn = Scene::new();
     scn.add_objects(vec![
@@ -40,9 +40,9 @@ fn main() {
 
     let mut film = Film::new(res);
     {
-        let coord = RenderCoord::new(&mut film, Vector2i::new_xy(32, 32), 100);
+        let coord = RenderCoord::new(&mut film, Vector2i::new_xy(32, 32), 300);
 
-        coord.work(&ctx, &mut sampler);
+        coord.run_threaded(&ctx, &mut sampler, 8);
     }
 
     let image = film.finalize_image();
diff --git a/src/render/coordinator.rs b/src/render/coordinator.rs
index a9a7d06..a8d8afb 100644
--- a/src/render/coordinator.rs
+++ b/src/render/coordinator.rs
@@ -7,7 +7,8 @@ use crate::camera::Film;
 use crate::core::{Bound2i, Vector2i};
 use crate::sample::Sampler;
 
-use std::sync::Mutex;
+use std::sync::{Arc, Mutex};
+use std::thread;
 
 struct Tiler {
     tilesize: Vector2i,
@@ -112,4 +113,15 @@ impl<'a> RenderCoord<'a> {
             self.finish_task(&task);
         }
     }
+
+    pub fn run_threaded(&self, ctx: &RenderContext, sampler: &mut (dyn Sampler + Send), threads: u32) {
+        crossbeam::scope(|scope| {
+            for _ in 0..threads {
+                let mut sampler = sampler.clone_and_seed();
+                scope.spawn(move |_| {
+                    self.work(ctx, sampler.as_mut());
+                });
+            }
+        }).unwrap();
+    }
 }
diff --git a/src/sample/mod.rs b/src/sample/mod.rs
index 88e1aa9..1a53921 100644
--- a/src/sample/mod.rs
+++ b/src/sample/mod.rs
@@ -16,6 +16,8 @@ pub trait Sampler {
         Vector2f::new_xy(self.get_sample(), self.get_sample())
     }
 
+    fn clone_and_seed(&mut self) -> Box<dyn Sampler + Send>;
+
     fn get_unit_vector(&mut self) -> Vector3f {
         let s2d = self.get_sample_2d();
 
diff --git a/src/sample/uniform.rs b/src/sample/uniform.rs
index 2cd3156..c144f27 100644
--- a/src/sample/uniform.rs
+++ b/src/sample/uniform.rs
@@ -30,4 +30,10 @@ impl Sampler for UniformSampler {
     fn get_sample(&mut self) -> Float {
         self.d.sample(&mut self.r)
     }
+
+    fn clone_and_seed(&mut self) -> Box<dyn Sampler + Send> {
+        let mut n = self.clone();
+        n.r = Pcg32::seed_from_u64(self.r.next_u64());
+        Box::new(n)
+    }
 }
diff --git a/src/world/mod.rs b/src/world/mod.rs
index ef239db..f0ba8d2 100644
--- a/src/world/mod.rs
+++ b/src/world/mod.rs
@@ -4,17 +4,17 @@ pub mod shapes;
 mod scene;
 pub use scene::*;
 
-use std::rc::Rc;
+use std::sync::Arc;
 use crate::core::Hittable;
 use crate::material::Material;
 
 pub struct Object {
-    pub shape: Box<dyn Hittable>,
-    pub mat: Rc<dyn Material>,
+    pub shape: Box<dyn Hittable + Sync>,
+    pub mat: Arc<dyn Material + Sync + Send>,
 }
 
 impl Object {
-    pub fn new(mat: Rc<dyn Material>, shape: Box<dyn Hittable>) -> Self {
+    pub fn new(mat: Arc<dyn Material + Sync + Send>, shape: Box<dyn Hittable + Sync>) -> Self {
         Object {
             mat,
             shape,
-- 
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