added scaling with sane default

assets/shaders/mandelbulb.wgsl

@@ -14,13 +14,17 @@ struct VoluMaterial {
     max_steps: i32,
     ray_epsilon: f32,
     normal_epsilon: f32,
+    scale: f32,
 }
 
 @group(2) @binding(100)
 var<storage, read> volu_material: VoluMaterial;
 
 fn mandelbulb_sdf(p: vec3<f32>) -> f32 {
-    var z = p;
+    let scale = volu_material.scale;
+    let p_scaled = p / scale;
+
+    var z = p_scaled;
     var dr = 1.0;
     var r = 0.0;
     let power = volu_material.power;
@@ -44,10 +48,10 @@ fn mandelbulb_sdf(p: vec3<f32>) -> f32 {
             sin(new_theta) * cos(new_phi),
             sin(new_theta) * sin(new_phi),
             cos(new_theta)
-        ) + p;
+        ) + p_scaled;
     }
 
-    return 0.5 * log(max(r, 0.001)) * r / dr;
+    return 0.5 * log(max(r, 0.001)) * r / dr * scale;
 }
 
 fn mandelbulb_normal(p: vec3<f32>) -> vec3<f32> {

src/mandelbulb.rs

@@ -28,6 +28,7 @@ struct MandelbulbSettings {
     max_steps: i32,
     ray_epsilon: f32,
     normal_epsilon: f32,
+    scale: f32,
 }
 
 impl Default for MandelbulbSettings {
@@ -39,6 +40,7 @@ impl Default for MandelbulbSettings {
             max_steps: 128,
             ray_epsilon: 0.001,
             normal_epsilon: 0.001,
+            scale: 0.7,
         }
     }
 }
@@ -63,6 +65,7 @@ fn update_volu_material(
             max_steps,
             ray_epsilon,
             normal_epsilon,
+            scale,
         } = *settings;
 
         let volu_storage = MandelbulbStorage {
@@ -74,6 +77,7 @@ fn update_volu_material(
             max_steps,
             ray_epsilon,
             normal_epsilon,
+            scale,
         };
 
         buffer.set_data(volu_storage);
@@ -114,4 +118,5 @@ pub struct MandelbulbStorage {
     max_steps: i32,
     ray_epsilon: f32,
     normal_epsilon: f32,
+    scale: f32,
 }