multithread rendering with rayon

src/generate.rs

@@ -1,13 +1,14 @@
 use eframe::epaint::Vec2;
 use image::{Rgb, RgbImage};
+use rayon::prelude::{IntoParallelIterator, ParallelIterator};
 use serde::{Deserialize, Serialize};
 
 #[derive(Clone, Serialize, Deserialize)]
 pub struct RenderOptions {
-	pub width: u32,
-	pub height: u32,
+	pub width: usize,
+	pub height: usize,
 	pub unit_width: f64,
-	pub iterations: u32,
+	pub max_iter: u16,
 	pub cx: f64,
 	pub cy: f64,
 	pub fill_style: FillStyle,
@@ -25,7 +26,7 @@ impl Default for RenderOptions {
 			width: 512,
 			height: 512,
 			unit_width: 4.0,
-			iterations: 128,
+			max_iter: 128,
 			cx: 0.4,
 			cy: -0.2,
 			fill_style: FillStyle::Bright,
@@ -33,57 +34,79 @@ impl Default for RenderOptions {
 	}
 }
 
-pub fn view_point(q: &RenderOptions, image: RgbImage) -> RgbImage {
-	apply_fn(image, q, |x, y| {
-		let len = (Vec2::new(x as f32, y as f32) - Vec2::new(q.cx as f32, q.cy as f32)).length();
-		if len < 0.03 {
-			Some(Rgb([0, 120, 120]))
-		} else if len < 0.04 {
-			Some(Rgb([255; 3]))
-		} else {
-			None
-		}
-	})
-}
+pub fn render_c(q: &RenderOptions, mut image: RgbImage) -> RgbImage {
+	let width = q.width as f32;
+	let height = q.height as f32;
+	let ppu = width / (q.unit_width as f32);
 
-pub fn render(q: &RenderOptions, color: (u8, u8, u8)) -> RgbImage {
-	let img = RgbImage::new(q.width, q.height);
-	apply_fn(img, q, |x, y| {
-		let i = julia(x, y, q.cx, q.cy, q.iterations);
-		if q.fill_style == FillStyle::Black && i == q.iterations {
-			None
-		} else {
-			let i = i.min(255) as u8;
-			Some(Rgb([
-				i.saturating_mul(color.0),
-				i.saturating_mul(color.1),
-				i.saturating_mul(color.2),
-			]))
-		}
-	})
-}
-
-fn apply_fn<F>(mut image: RgbImage, q: &RenderOptions, op: F) -> RgbImage
-where
-	F: Fn(f64, f64) -> Option<Rgb<u8>>,
-{
-	let width = q.width as f64;
-	let height = q.height as f64;
-	let ppu = width / q.unit_width;
+	let target = Vec2::new(q.cx as f32, q.cy as f32);
 
 	for y in 0..q.height {
 		for x in 0..q.width {
-			let sx = (x as f64 - width / 2.0) / ppu;
-			let sy = (y as f64 - height / 2.0) / ppu;
-			if let Some(pixel) = op(sx, sy) {
-				image.put_pixel(x, y, pixel);
+			let sx = (x as f32 - width / 2.0) / ppu;
+			let sy = (y as f32 - height / 2.0) / ppu;
+
+			let len = (Vec2::new(sx, sy) - target).length();
+			if len < 0.03 {
+				image.put_pixel(x as u32, y as u32, Rgb([0, 120, 120]));
+			} else if len < 0.04 {
+				image.put_pixel(x as u32, y as u32, Rgb([255; 3]));
 			}
 		}
 	}
 	image
 }
 
-fn julia(mut x: f64, mut y: f64, cx: f64, cy: f64, max_iter: u32) -> u32 {
+pub fn color_iteration(iter: u16, color: (u8, u8, u8)) -> Rgb<u8> {
+	let i = iter.min(255) as u8;
+	Rgb([
+		i.saturating_mul(color.0),
+		i.saturating_mul(color.1),
+		i.saturating_mul(color.2),
+	])
+}
+
+pub fn render_julia(q: &RenderOptions, color: (u8, u8, u8)) -> RgbImage {
+	let mut image = RgbImage::new(q.width as u32, q.height as u32);
+
+	let width = q.width as f64;
+	let height = q.height as f64;
+	let ppu = width / q.unit_width;
+
+	let fill = match q.fill_style {
+		FillStyle::Black => Rgb([0; 3]),
+		FillStyle::Bright => color_iteration(q.max_iter, color),
+	};
+
+	(0..q.height)
+		.into_par_iter()
+		.map(|y| {
+			let mut row = Vec::with_capacity(q.width);
+			for x in 0..q.width {
+				let sx = (x as f64 - width / 2.0) / ppu;
+				let sy = (y as f64 - height / 2.0) / ppu;
+				let i = julia(sx, sy, q.cx, q.cy, q.max_iter);
+
+				if i == q.max_iter {
+					row.push(fill);
+				} else {
+					row.push(color_iteration(i, color));
+				}
+			}
+			row
+		})
+		.collect::<Vec<_>>()
+		.into_iter()
+		.enumerate()
+		.for_each(|(y, row)| {
+			for (x, i) in row.into_iter().enumerate() {
+				image.put_pixel(x as u32, y as u32, i);
+			}
+		});
+	image
+}
+
+fn julia(mut x: f64, mut y: f64, cx: f64, cy: f64, max_iter: u16) -> u16 {
 	let mut iter = 0;
 	while (x * x + y * y) < 4.0 && iter < max_iter {
 		(x, y) = (

src/main.rs

@@ -13,7 +13,7 @@ use eframe::{
 	epaint::{TextureHandle, Vec2},
 	Frame, NativeOptions,
 };
-use generate::{render, view_point, FillStyle, RenderOptions};
+use generate::{render_c, render_julia, FillStyle, RenderOptions};
 use image::EncodableLayout;
 use native_dialog::FileDialog;
 use serde::{Deserialize, Serialize};
@@ -47,7 +47,7 @@ struct JuliaGUI {
 	#[serde(skip)]
 	export_render_ms: Option<f64>,
 	export_res_power: u8,
-	export_iterations: u32,
+	export_max_iter: u16,
 	#[serde(skip)]
 	export_path: PathBuf,
 	#[serde(skip)]
@@ -77,7 +77,7 @@ impl Default for JuliaGUI {
 			preview_render_ms: 0.0,
 			export_render_ms: None,
 			export_res_power: 3,
-			export_iterations: 512,
+			export_max_iter: 512,
 			export_path: "".into(),
 			settings_changed: true,
 			preview_point: false,
@@ -113,7 +113,7 @@ impl JuliaGUI {
 						RenderJob::Exit => break,
 						RenderJob::Render(path, options, color) => {
 							let start_time = SystemTime::now();
-							let image = render(&options, color);
+							let image = render_julia(&options, color);
 							if let Err(err) = image.save(&path) {
 								println!("Failed to save render: {err}");
 							}
@@ -142,9 +142,9 @@ impl JuliaGUI {
 
 	fn update_preview(&mut self) {
 		let start_time = SystemTime::now();
-		let mut frame = render(&self.settings, self.color);
+		let mut frame = render_julia(&self.settings, self.color);
 		if self.preview_point {
-			frame = view_point(&self.settings, frame);
+			frame = render_c(&self.settings, frame);
 		}
 
 		if let Some(preview) = &mut self.preview {
@@ -166,7 +166,7 @@ impl JuliaGUI {
 			let settings = RenderOptions {
 				width: self.settings.width * res_mul,
 				height: self.settings.height * res_mul,
-				iterations: self.export_iterations,
+				max_iter: self.export_max_iter,
 				..self.settings.clone()
 			};
 
@@ -272,8 +272,8 @@ impl eframe::App for JuliaGUI {
 				let set_blue = ui.add(Slider::new(&mut self.color.2, 0..=16));
 
 				ui.label("Preview iterations:");
-				let set_iter = ui
-					.add(Slider::new(&mut self.settings.iterations, 5..=256).clamp_to_range(false));
+				let set_iter =
+					ui.add(Slider::new(&mut self.settings.max_iter, 5..=256).clamp_to_range(false));
 
 				ui.horizontal(|ui| {
 					ui.label("Preview resolution:");
@@ -313,7 +313,7 @@ impl eframe::App for JuliaGUI {
 				});
 
 				ui.label("Render iterations:");
-				ui.add(Slider::new(&mut self.export_iterations, 5..=1024).clamp_to_range(false));
+				ui.add(Slider::new(&mut self.export_max_iter, 5..=1024).clamp_to_range(false));
 				ui.label("Render resolution:");
 				ui.add(Slider::new(&mut self.export_res_power, 0..=6).clamp_to_range(false));
 				ui.label(format!(
@@ -350,7 +350,7 @@ impl eframe::App for JuliaGUI {
 
 				let predicted_render_time = (self.preview_render_ms
 					* (1 << (self.export_res_power * 2)) as f64
-					* (self.export_iterations as f64 / self.settings.iterations as f64)
+					* (self.export_max_iter as f64 / self.settings.max_iter as f64)
 					/ 1000.0)
 					.floor();
 				if predicted_render_time < 60.0 {