light bath on oktween

1 files changed, 51 insertions, 0 deletions

diff --git a/client/util/math.js b/client/util/math.js
new file mode 100644
index 00000000..064d37c6
--- /dev/null
+++ b/client/util/math.js
@@ -0,0 +1,51 @@
+export const mod = (n,m) => n-(m * Math.floor(n/m))
+export const clamp = (n,a,b) => n<a?a:n<b?n:b
+export const norm = (n,a,b) => (n-a) / (b-a)
+export const lerp = (n,a,b) => (b-a)*n+a
+export const mix = (n,a,b) => a*(1-n)+b*n
+export const randint = (n) => Math.floor(Math.random()*n)
+export const randrange = (a,b) => Math.random() * (b-a) + a
+export const randsign = () => Math.random() >= 0.5 ? -1 : 1
+export const choice = (a) => a[ Math.floor(Math.random() * a.length) ]
+export const angle = (x0,y0,x1,y1) => Math.atan2(y1-y0, x1-x0)
+export const dist = (x0,y0,x1,y1) => Math.sqrt(Math.pow(x1-x0, 2) + Math.pow(y1-y0, 2))
+export const xor = (a,b) => { a=!!a; b=!!b; return (a||b) && !(a&&b) }
+export const quantize = (a,b) => Math.floor(a/b)*b
+export const shuffle = (a) => {
+  for (var i = a.length; i > 0; i--){
+    var r = randint(i)
+    var swap = a[i-1]
+    a[i-1] = a[r]
+    a[r] = swap
+  }
+  return a
+}
+// returns a gaussian random function with the given mean and stdev.
+export function gaussian(mean, stdev) {
+  let y2;
+  let use_last = false;
+  return () => {
+    let y1;
+    if (use_last) {
+      y1 = y2;
+      use_last = false;
+    }
+    else {
+      let x1, x2, w;
+      do {
+        x1 = 2.0 * Math.random() - 1.0;
+        x2 = 2.0 * Math.random() - 1.0;
+        w  = x1 * x1 + x2 * x2;               
+      } while( w >= 1.0);
+      w = Math.sqrt((-2.0 * Math.log(w))/w);
+      y1 = x1 * w;
+      y2 = x2 * w;
+      use_last = true;
+    }
+
+    let retval = mean + stdev * y1;
+    if (retval > 0) 
+      return retval;
+    return -retval;
+  }
+}