render c point in preview

src/generate.rs

@@ -1,3 +1,4 @@
+use eframe::epaint::Vec2;
 use image::{Rgb, RgbImage};
 use serde::{Deserialize, Serialize};
 
@@ -32,35 +33,54 @@ impl Default for RenderOptions {
 	}
 }
 
-pub fn render(q: &RenderOptions, color: (u8, u8, u8)) -> RgbImage {
-	let mut img = RgbImage::new(q.width, q.height);
+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 < 0.04 {
+			Some(Rgb([0, 255, 255]))
+		} else if len < 0.05 {
+			Some(Rgb([255; 3]))
+		} else {
+			None
+		}
+	})
+}
 
-	let width: f64 = q.width.into();
-	let height: f64 = q.height.into();
+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.max_iterations);
+		if q.fill_style == FillStyle::Black && i == q.max_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;
 
 	for y in 0..q.height {
 		for x in 0..q.width {
-			let pixel = {
-				let x = (f64::from(x) - width / 2.0) / ppu;
-				let y = (f64::from(y) - height / 2.0) / ppu;
-
-				let iter = julia(x, y, q.cx, q.cy, q.max_iterations);
-				if q.fill_style == FillStyle::Black && iter == q.max_iterations {
-					Rgb([0, 0, 0])
-				} else {
-					let i = iter.min(255) as u8;
-					Rgb([
-						i.saturating_mul(color.0),
-						i.saturating_mul(color.1),
-						i.saturating_mul(color.2),
-					])
-				}
-			};
-			img.put_pixel(x, y, pixel);
+			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);
 			}
 		}
-	img
+	}
+	image
 }
 
 fn julia(mut x: f64, mut y: f64, cx: f64, cy: f64, max_iter: u32) -> u32 {

src/main.rs

@@ -11,7 +11,7 @@ use eframe::{
 	epaint::{TextureHandle, Vec2},
 	Frame, NativeOptions,
 };
-use generate::{render, FillStyle, RenderOptions};
+use generate::{render, view_point, FillStyle, RenderOptions};
 use image::EncodableLayout;
 use native_dialog::FileDialog;
 use serde::{Deserialize, Serialize};
@@ -50,6 +50,7 @@ struct JuliaGUI {
 	export_path: PathBuf,
 	#[serde(skip)]
 	settings_changed: bool,
+	preview_point: bool,
 }
 
 impl Default for JuliaGUI {
@@ -60,10 +61,11 @@ impl Default for JuliaGUI {
 			render_options: RenderOptions::default(),
 			preview_render_ms: 0.0,
 			export_render_ms: None,
-			export_res_power: 8,
+			export_res_power: 3,
 			export_iterations: 512,
 			export_path: "".into(),
 			settings_changed: true,
+			preview_point: true,
 		}
 	}
 }
@@ -96,7 +98,10 @@ impl JuliaGUI {
 
 	fn update_preview(&mut self) {
 		let start_time = SystemTime::now();
-		let frame = render(&self.render_options, self.color);
+		let mut frame = render(&self.render_options, self.color);
+		if self.preview_point {
+			frame = view_point(&self.render_options, frame);
+		}
 
 		if let Some(preview) = &mut self.preview {
 			preview.set(
@@ -129,7 +134,7 @@ impl JuliaGUI {
 
 	fn export_render_new_path(&mut self) {
 		if let Ok(Some(path)) = FileDialog::new()
-			.set_filename(&self.export_path.to_string_lossy().to_string())
+			.set_filename(&self.export_path.to_string_lossy())
 			.add_filter("PNG file", &["png"])
 			.show_save_single_file()
 		{
@@ -156,6 +161,7 @@ impl eframe::App for JuliaGUI {
 					self.preview_render_ms
 				));
 
+				let set_point_vis = ui.checkbox(&mut self.preview_point, "View C point");
 				ui.label("CX:");
 				let set_cx = ui.add(Slider::new(&mut self.render_options.cx, -2.0..=2.0));
 				ui.label("CY:");
@@ -242,7 +248,7 @@ impl eframe::App for JuliaGUI {
 						.to_string(),
 				);
 				if let Some(ms) = self.export_render_ms {
-					ui.label(format!("(took {:.2}ms)", ms));
+					ui.label(format!("(took {ms:.2}ms)"));
 				}
 
 				if set_cx.changed()
@@ -250,6 +256,7 @@ impl eframe::App for JuliaGUI {
 					|| set_iter.changed()
 					|| set_red.changed() || set_green.changed()
 					|| set_blue.changed()
+					|| set_point_vis.changed()
 				{
 					self.settings_changed = true;
 				}
@@ -263,6 +270,6 @@ impl eframe::App for JuliaGUI {
 	}
 
 	fn on_exit(&mut self, _gl: Option<&eframe::glow::Context>) {
-		self.save_settings()
+		self.save_settings();
 	}
 }