feat: lossless share links + auto iteration count

src/fractal/share.rs

@@ -14,6 +14,8 @@ use crate::fractal::FractalKind;
 pub struct ShareState {
     pub julia: bool,
     pub kind: FractalKind,
+    /// Exponent for the Multibrot kind (ignored by others).
+    pub power: u32,
     pub center_re: String,
     pub center_im: String,
     pub half_height: f64,
@@ -21,6 +23,8 @@ pub struct ShareState {
     pub julia_c: (f64, f64),
     pub color_scale: f32,
     pub color_offset: f32,
+    /// Palette index (`palette_id` in the shader).
+    pub palette: u32,
 }
 
 impl ShareState {
@@ -33,14 +37,15 @@ impl ShareState {
             FractalKind::Multibrot => "multi",
             FractalKind::Tricorn => "tricorn",
         }));
+        s.push_str(&format!("&pw={}", self.power));
         s.push_str(&format!(
             "&re={}&im={}&hh={}&it={}",
             self.center_re, self.center_im, self.half_height, self.iterations
         ));
         s.push_str(&format!("&jr={}&ji={}", self.julia_c.0, self.julia_c.1));
         s.push_str(&format!(
-            "&cs={}&co={}",
-            self.color_scale, self.color_offset
+            "&cs={}&co={}&pal={}",
+            self.color_scale, self.color_offset, self.palette
         ));
         s
     }
@@ -66,6 +71,7 @@ impl ShareState {
                     _ => FractalKind::Mandelbrot
                 })
                 .unwrap_or(FractalKind::Mandelbrot),
+            power: map.get("pw").and_then(|s| s.parse().ok()).unwrap_or(2),
             center_re: (*map.get("re")?).to_string(),
             center_im: (*map.get("im")?).to_string(),
             half_height: map.get("hh")?.parse().ok()?,
@@ -76,6 +82,7 @@ impl ShareState {
             ),
             color_scale: map.get("cs").and_then(|s| s.parse().ok()).unwrap_or(0.02),
             color_offset: map.get("co").and_then(|s| s.parse().ok()).unwrap_or(0.0),
+            palette: map.get("pal").and_then(|s| s.parse().ok()).unwrap_or(0),
         })
     }
 }
@@ -88,7 +95,8 @@ mod tests {
     fn round_trip() {
         let s = ShareState {
             julia: true,
-            kind: FractalKind::Tricorn,
+            kind: FractalKind::Multibrot,
+            power: 5,
             center_re: "-0.743643887037158704752191506114774".into(),
             center_im: "0.131825904205311970493132056385139".into(),
             half_height: 1.5e-20,
@@ -96,15 +104,18 @@ mod tests {
             julia_c: (-0.123, 0.745),
             color_scale: 0.02,
             color_offset: 0.25,
+            palette: 3,
         };
         let d = ShareState::decode(&s.encode()).unwrap();
         assert_eq!(d.julia, s.julia);
         assert_eq!(d.kind, s.kind);
+        assert_eq!(d.power, s.power);
         assert_eq!(d.center_re, s.center_re);
         assert_eq!(d.center_im, s.center_im);
         assert_eq!(d.half_height, s.half_height);
         assert_eq!(d.iterations, s.iterations);
         assert_eq!(d.julia_c, s.julia_c);
+        assert_eq!(d.palette, s.palette);
     }
 
     #[test]