From 3a144c8c1fc83150fc06d792082db5cc4bce3cc5 Mon Sep 17 00:00:00 2001
From: Julian T <julian@jtle.dk>
Date: Tue, 9 Feb 2021 20:00:52 +0100
Subject: Add tiling for rendering

---
 src/render/coordinator.rs | 115 ++++++++++++++++++++++++++++++++++++++++++++++
 src/render/mod.rs         |   5 ++
 src/render/task.rs        |  49 ++++++++++++++++++++
 3 files changed, 169 insertions(+)
 create mode 100644 src/render/coordinator.rs
 create mode 100644 src/render/mod.rs
 create mode 100644 src/render/task.rs

(limited to 'src/render')

diff --git a/src/render/coordinator.rs b/src/render/coordinator.rs
new file mode 100644
index 0000000..a9a7d06
--- /dev/null
+++ b/src/render/coordinator.rs
@@ -0,0 +1,115 @@
+//! Split a image into small tiles
+//!
+//! This enables multithreaded rendering.
+
+use super::{RenderTask, RenderContext};
+use crate::camera::Film;
+use crate::core::{Bound2i, Vector2i};
+use crate::sample::Sampler;
+
+use std::sync::Mutex;
+
+struct Tiler {
+    tilesize: Vector2i,
+
+    fullbound: Bound2i,
+    tilemap_size: Vector2i,
+    tilemap_area: i32,
+
+    next_tile: i32,
+    tiles_done: i32,
+}
+
+pub struct RenderCoord<'a> {
+    film: Mutex<&'a mut Film>,
+    samples: u32,
+    tiler: Mutex<Tiler>,
+}
+
+impl Tiler {
+    pub fn new(fullsize: Vector2i, tilesize: Vector2i) -> Tiler {
+        assert!(tilesize.x != 0 && tilesize.y != 0);
+
+        let tilemap_size = fullsize / tilesize;
+
+        Self {
+            tilesize,
+
+            fullbound: Bound2i::new(&Vector2i::ZERO, &fullsize),
+            tilemap_size,
+            tilemap_area: (tilemap_size.x * tilemap_size.y),
+
+            next_tile: 0,
+            tiles_done: 0,
+        }
+
+    }
+
+    pub fn next_tile(&mut self) -> Option<(Bound2i, i32)> {
+        // Check if we are outside
+        if self.next_tile >= self.tilemap_area {
+            return None;
+        }
+
+        // Convert the tile to xy in tilemap
+        let tile = Vector2i::new_xy(self.next_tile / self.tilemap_size.x, self.next_tile % self.tilemap_size.x);
+        let tile_index = self.next_tile;
+
+        self.next_tile += 1;
+
+        // Create a bound from the tilecoordinate
+        let tile_start = tile * self.tilesize;
+        // We need to make sure the resulting tile is inside the image bound
+        Some((
+                Bound2i::new(&tile_start, &(tile_start + self.tilesize)).intersect(&self.fullbound),
+                tile_index,
+                ))
+    }
+
+    /// Mark a index as done and return the overall process
+    pub fn mark_done(&mut self, _index: i32) -> f32 {
+        self.tiles_done += 1;
+
+        println!("Progress: {}/{}", self.tiles_done, self.tilemap_area);
+        self.tiles_done as f32 / self.tilemap_area as f32
+    }
+}
+
+impl<'a> RenderCoord<'a> {
+    pub fn new(film: &'a mut Film, tilesize: Vector2i, samples: u32) -> Self {
+        let size = film.size;
+
+        Self {
+            film: Mutex::new(film),
+            samples,
+            tiler: Mutex::new(Tiler::new(size, tilesize)),
+        }
+    }
+
+    pub fn next_task(&self) -> Option<RenderTask> {
+        let (tile_bound, index) = self.tiler.lock().unwrap().next_tile()?;
+
+        let film_tile = {
+            let film = self.film.lock().unwrap();
+            Box::new(film.get_tile(&tile_bound))
+        };
+
+        Some(RenderTask::new(film_tile, self.samples, index))
+    }
+
+    pub fn finish_task(&self, task: &RenderTask) {
+        {
+            let mut film = self.film.lock().unwrap();
+            film.commit_tile(task.tile.as_ref());
+        }
+
+        self.tiler.lock().unwrap().mark_done(task.tile_index);
+    }
+
+    pub fn work(&self, ctx: &RenderContext, sampler: &mut dyn Sampler) {
+        while let Some(mut task) = self.next_task() {
+            task.render(ctx, sampler);
+            self.finish_task(&task);
+        }
+    }
+}
diff --git a/src/render/mod.rs b/src/render/mod.rs
new file mode 100644
index 0000000..b81aaf5
--- /dev/null
+++ b/src/render/mod.rs
@@ -0,0 +1,5 @@
+mod task;
+mod coordinator;
+
+pub use task::{RenderContext, RenderTask};
+pub use coordinator::RenderCoord;
diff --git a/src/render/task.rs b/src/render/task.rs
new file mode 100644
index 0000000..017fe24
--- /dev/null
+++ b/src/render/task.rs
@@ -0,0 +1,49 @@
+//! Implements the main render loop
+//!
+//! This is not a final design
+use crate::camera::film::FilmTile;
+use crate::camera::Camera;
+use crate::trace::{DefaultTracer, Tracer};
+use crate::sample::Sampler;
+
+use crate::core::{Vector2f};
+use crate::Float;
+
+pub struct RenderTask {
+    pub tile: Box<FilmTile>,
+    samples: u32,
+    pub tile_index: i32,
+}
+
+pub struct RenderContext<'a> {
+    pub cam: &'a Camera,
+    pub trc: &'a DefaultTracer<'a>,
+}
+
+impl RenderTask {
+    pub fn new(tile: Box<FilmTile>, samples: u32, tile_index: i32) -> Self {
+        Self { tile, samples, tile_index }
+    }
+
+    fn render_at(&mut self, ctx: &RenderContext, x: i32, y: i32, sampler: &mut dyn Sampler) {
+        let corner = Vector2f::new_xy(x as Float, y as Float);
+
+        for _ in 0..self.samples {
+            let p = corner + sampler.get_sample_2d();
+
+            // Create a ray
+            let (r, _) = ctx.cam.generate_ray(&p, sampler);
+
+            self.tile.add_sample(&p, ctx.trc.trace(sampler, &r));
+        }
+    }
+
+    pub fn render(&mut self, ctx: &RenderContext, sampler: &mut dyn Sampler) {
+        let b = self.tile.bounds.clone();
+        for y in b.min.y .. b.max.y {
+            for x in b.min.x .. b.max.x {
+                self.render_at(ctx, x, y, sampler);
+            }
+        }
+    }
+}
-- 
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