a large number of small ui changes

src/generator.rs

@@ -28,7 +28,7 @@ impl Default for GenerationParams {
         Self {
             image_width: 512,
             image_height: 512,
-            generation_scale: 6.0,
+            generation_scale: 1.0,
             erosion_scale: 0.15,
             random_seed: 0,
             erosion_strength: 0.05,
@@ -124,9 +124,10 @@ fn clamp01(x: f32) -> f32 {
 }
 
 fn hash22(p: Vec2, random_seed: u64) -> Vec2 {
-    let seed = random_seed as f64;
-    let seed_x = seed * 0.754_877_666_246_692_7;
-    let seed_y = seed * 0.569_840_290_998_053_2;
+    let scrambled_x = splitmix64(random_seed ^ 0x9E37_79B9_7F4A_7C15);
+    let scrambled_y = splitmix64(random_seed ^ 0xBF58_476D_1CE4_E5B9);
+    let seed_x = u64_to_unit_f64(scrambled_x) * 1024.0;
+    let seed_y = u64_to_unit_f64(scrambled_y) * 1024.0;
     let kx = 0.318_309_9_f64;
     let ky = 0.367_879_4_f64;
 
@@ -140,6 +141,18 @@ fn hash22(p: Vec2, random_seed: u64) -> Vec2 {
     Vec2::new(rx as f32, ry as f32)
 }
 
+fn splitmix64(mut x: u64) -> u64 {
+    x = x.wrapping_add(0x9E37_79B9_7F4A_7C15);
+    x = (x ^ (x >> 30)).wrapping_mul(0xBF58_476D_1CE4_E5B9);
+    x = (x ^ (x >> 27)).wrapping_mul(0x94D0_49BB_1331_11EB);
+    x ^ (x >> 31)
+}
+
+fn u64_to_unit_f64(value: u64) -> f64 {
+    const SCALE: f64 = 1.0 / (u64::MAX as f64);
+    (value as f64) * SCALE
+}
+
 fn noised(p: Vec2, random_seed: u64) -> (f32, Vec2) {
     let i = Vec2::new(p.x.floor(), p.y.floor());
     let f = Vec2::new(p.x - i.x, p.y - i.y);