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feat: add buddhabrot fractal

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This commit is contained in:
surv
2026-09-16 22:04:21 +02:00
parent afcd3c74da
commit 7c347a5abf
6 changed files with 853 additions and 9 deletions
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src/app.rs
+163 -7
View File
@@ -5,8 +5,8 @@ use eframe::egui_wgpu;
use eframe::egui_wgpu::wgpu;
use crate::fractal::{
ExportRender, FractalCallback, FractalKind, FractalRenderer, MAX_REF_POINTS, ShareState,
Uniforms,
BuddhabrotCallback, BuddhabrotRenderer, BuddhabrotUniforms, ExportRender, FractalCallback,
FractalKind, FractalRenderer, MAX_REF_POINTS, ShareState, Uniforms,
};
#[cfg(target_arch = "wasm32")]
use crate::fractal::{compute_reference, compute_set_reference};
@@ -29,6 +29,8 @@ const INTERACT_DOWNSCALE: u32 = 2;
const INTERACT_SETTLE: f64 = 0.12;
/// Palette names; index maps to `palette_id` in the shader.
const PALETTE_NAMES: &[&str] = &["Amber", "Rainbow", "Ember", "Lime", "Grayscale"];
/// Buddhabrot tonemap style names; index maps to `BuddhabrotUniforms::palette`.
const BUDDHA_PALETTE_NAMES: &[&str] = &["Nebula", "Yellow", "Grayscale"];
#[derive(Clone, Copy, PartialEq, Eq)]
pub enum FractalMode {
@@ -265,6 +267,23 @@ pub struct FractalApp {
/// Distance-estimation shading: darkens toward the set boundary using the
/// orbit derivative, giving crisp filaments at deep zoom instead of speckle.
de_coloring: bool,
/// Render as a Buddhabrot (Monte-Carlo orbit-density histogram) instead of
/// the ordinary escape-time set. Plain f32 view — no deep zoom, no
/// perturbation/reference-orbit machinery (see `fractal::buddhabrot`).
buddhabrot: bool,
/// Nested escape-iteration caps for the R/G/B histogram channels
/// (Nebulabrot coloring); kept ordered r <= g <= b by the UI.
buddha_r_cap: u32,
buddha_g_cap: u32,
buddha_b_cap: u32,
/// Tonemap brightness multiplier.
buddha_exposure: f32,
/// Tonemap colour style (index into `BUDDHA_PALETTE_NAMES`).
buddha_palette: u32,
/// Keep dispatching new sample batches every frame (progressive
/// accumulation). Turning it off freezes the current histogram.
buddha_accumulate: bool,
/// Whether the controls side panel is expanded. Collapsible so the fractal
/// can take (nearly) the whole screen — important on a phone.
controls_open: bool,
@@ -352,11 +371,13 @@ impl FractalApp {
.expect("eframe must run with the wgpu backend");
let renderer = FractalRenderer::new(&render_state.device, render_state.target_format);
render_state
.renderer
.write()
.callback_resources
.insert(renderer);
let buddhabrot_renderer =
BuddhabrotRenderer::new(&render_state.device, render_state.target_format);
{
let mut guard = render_state.renderer.write();
guard.callback_resources.insert(renderer);
guard.callback_resources.insert(buddhabrot_renderer);
}
let view = ViewState::default();
let ref_center_re = view.center_re.clone();
@@ -382,6 +403,13 @@ impl FractalApp {
palette: 0,
antialias: false,
de_coloring: false,
buddhabrot: false,
buddha_r_cap: 50,
buddha_g_cap: 500,
buddha_b_cap: 2000,
buddha_exposure: 1.0,
buddha_palette: 0,
buddha_accumulate: true,
controls_open: true,
fullscreen: false,
anim: AnimState::default(),
@@ -460,6 +488,14 @@ impl FractalApp {
if std::env::var("MANDEL_DE").is_ok() {
app.de_coloring = true;
}
if std::env::var("MANDEL_BUDDHABROT").is_ok() {
app.buddhabrot = true;
}
if let Ok(p) = std::env::var("MANDEL_BUDDHA_PALETTE")
&& let Ok(p) = p.trim().parse::<u32>()
{
app.buddha_palette = p.min(BUDDHA_PALETTE_NAMES.len() as u32 - 1);
}
if std::env::var("MANDEL_EXPORT").is_ok() {
app.export_requested = true;
}
@@ -777,6 +813,37 @@ impl FractalApp {
}
}
/// Buddhabrot pass uniforms. Unlike `make_uniforms`, the view center is
/// collapsed straight to f32 (no arbitrary-precision reference orbit) —
/// Buddhabrot mode doesn't support deep zoom (see `fractal::buddhabrot`).
fn make_buddhabrot_uniforms(&self, aspect: f64) -> BuddhabrotUniforms {
let center = [
self.view.center_re.to_f64().value() as f32,
self.view.center_im.to_f64().value() as f32,
];
BuddhabrotUniforms {
center,
half_height: self.view.half_height as f32,
aspect: aspect as f32,
phoenix_p: [self.phoenix_p.0 as f32, self.phoenix_p.1 as f32],
lambda_l: [self.lambda_l.0 as f32, self.lambda_l.1 as f32],
bailout_sq: BAILOUT_SQ,
kind: self.kind as u32,
power: self.power,
r_cap: self.buddha_r_cap,
g_cap: self.buddha_g_cap,
b_cap: self.buddha_b_cap,
seed: 0, // set by the callback's own dispatch counter
samples_this_dispatch: 0, // set by the callback
exposure: self.buddha_exposure,
width: 0, // set by the callback from size_px
height: 0, // set by the callback from size_px
total_samples: 0.0, // tracked by the renderer across frames
palette: self.buddha_palette,
_pad: [0; 3],
}
}
/// Render the current view to a PNG at `export_scale` × the on-screen size,
/// then save it (native: file in cwd; web: browser download). Runs off the
/// UI thread so a progress bar can animate; progress lands in `self.export`.
@@ -784,6 +851,10 @@ impl FractalApp {
if self.export.is_some() {
return; // one export at a time
}
if self.buddhabrot {
self.status = Some("PNG export isn't available in Buddhabrot mode yet".into());
return;
}
let Some(rs) = frame.wgpu_render_state() else {
self.status = Some("export unavailable (no wgpu backend)".into());
return;
@@ -1195,6 +1266,24 @@ impl FractalApp {
self.view = Self::default_view_for(self.mode, self.kind);
}
ui.checkbox(&mut self.buddhabrot, "Buddhabrot")
.on_hover_text(
"Monte-Carlo density of escaping orbits instead of the ordinary \
escape-time set. Plain f32 view (no deep zoom); the image \
progressively sharpens while the view stays still.",
);
if self.buddhabrot {
self.buddhabrot_ui(ui);
ui.separator();
if ui.button("Reset view").clicked() {
self.view = Self::default_view_for(self.mode, self.kind);
}
ui.add_space(8.0);
ui.small("Drag to pan · scroll to zoom toward the cursor");
return;
}
ui.horizontal(|ui| {
ui.radio_value(&mut self.mode, FractalMode::Mandelbrot, "Set");
ui.radio_value(&mut self.mode, FractalMode::Julia, "Julia");
@@ -1484,6 +1573,48 @@ impl FractalApp {
ui.small("Drag to pan · scroll to zoom toward the cursor");
}
/// Controls for Buddhabrot mode: nested iteration caps (Nebulabrot R/G/B
/// coloring), exposure, and the progressive-accumulation toggle.
fn buddhabrot_ui(&mut self, ui: &mut egui::Ui) {
ui.separator();
ui.add(
egui::Slider::new(&mut self.buddha_r_cap, 5..=5_000)
.text("red cap")
.logarithmic(true),
);
ui.add(
egui::Slider::new(&mut self.buddha_g_cap, 5..=20_000)
.text("green cap")
.logarithmic(true),
);
ui.add(
egui::Slider::new(&mut self.buddha_b_cap, 5..=50_000)
.text("blue cap")
.logarithmic(true),
);
ui.add(
egui::Slider::new(&mut self.buddha_exposure, 0.02..=50.0)
.text("exposure")
.logarithmic(true),
);
egui::ComboBox::from_label("colors")
.selected_text(BUDDHA_PALETTE_NAMES[self.buddha_palette as usize])
.show_ui(ui, |ui| {
for (i, name) in BUDDHA_PALETTE_NAMES.iter().enumerate() {
ui.selectable_value(&mut self.buddha_palette, i as u32, *name);
}
});
ui.checkbox(&mut self.buddha_accumulate, "Keep sampling")
.on_hover_text("Dispatch a fresh batch of random samples every frame.");
if self.view.magnification() > 1.0e5 {
ui.colored_label(
egui::Color32::LIGHT_YELLOW,
"deep zoom isn't supported here (f32 precision only)",
);
}
ui.small("PNG export isn't available in Buddhabrot mode yet.");
}
fn fractal_ui(&mut self, ui: &mut egui::Ui) {
let size = ui.available_size();
let (rect, response) = ui.allocate_exact_size(size, egui::Sense::click_and_drag());
@@ -1544,6 +1675,31 @@ impl FractalApp {
ui.ctx().request_repaint();
}
if self.buddhabrot {
// No reference orbit / perturbation machinery: iterate directly in
// f32 from the live view. Progressive accumulation means this
// needs its own continuous repaint, separate from the escape-time
// interaction-driven one above.
let ppp = ui.ctx().pixels_per_point();
let size_px = [
((rect.width() * ppp).round() as u32).max(1),
((rect.height() * ppp).round() as u32).max(1),
];
let uniforms = self.make_buddhabrot_uniforms(aspect);
ui.painter().add(egui_wgpu::Callback::new_paint_callback(
rect,
BuddhabrotCallback {
uniforms,
accumulate: self.buddha_accumulate,
size_px,
},
));
if self.buddha_accumulate {
ui.ctx().request_repaint();
}
return;
}
// Keep the iteration count matched to the zoom depth while auto is on.
if self.auto_iterations {
self.max_iterations = self.auto_iteration_count();