Finalize marble parameters for scene/final.

Add pixel_scale parameter to noise_explorer to allow scaling of p vector
passed to value function.

rtiow/src/noise/mod.rs

@@ -9,7 +9,8 @@ pub trait NoiseSource: Send + Sync {
     /// value returns noise on the interval [0., 1.).
     fn value(&self, p: Vec3) -> f32;
 
-    fn marble(&self, p: Vec3, period: Vec3, power: f32, size: usize) -> f32 {
+    fn marble(&self, p: Vec3, period: Vec3, power: f32, size: usize, scale: f32) -> f32 {
+        let p = p / scale;
         // TODO(wathiede): can't understand why 255 works for perlin and lode, maybe it's near 360
         // degrees and interacts with the sine function?
         let xyz_value = p.x * period.x / 255.
@@ -52,6 +53,7 @@ pub enum NoiseType {
         period: Vec3,
         power: f32,
         size: usize,
+        scale: f32,
     },
 }
 
@@ -64,9 +66,10 @@ impl NoiseType {
                 period,
                 power,
                 size,
+                scale,
             } => format!(
-                "marble/period/{},{},{}/power/{}/size/{}",
-                period.x, period.y, period.z, power, size,
+                "marble/period/{},{},{}/power/{}/size/{}/scale/{}",
+                period.x, period.y, period.z, power, size, scale
             ),
         }
     }
@@ -79,10 +82,12 @@ impl NoiseType {
                 period,
                 power,
                 size,
+                scale,
             } => vec![
                 ("Period", period.to_string()),
                 ("Power", power.to_string()),
                 ("Size", size.to_string()),
+                ("Scale", scale.to_string()),
             ],
         }
     }