Ticket #4276: 4276_boxmuller.diff

binaries/data/mods/public/simulation/components/Attack.js

@@ -441 +441 @@
 
 // Returns a 2d random distribution scaled for a spread of scale 1.
 // The current implementation is a 2d gaussian with sigma = 1
 Attack.prototype.GetNormalDistribution = function(){
 
-    // Use the Box-Muller transform to get a gaussian distribution
-    let a = Math.random();
-    let b = Math.random();
-
-    let c = Math.sqrt(-2*Math.log(a)) * Math.cos(2*Math.PI*b);
-    let d = Math.sqrt(-2*Math.log(a)) * Math.sin(2*Math.PI*b);
-
-    return [c, d];
+    // Use the Box-Muller transform with the polar method to get a gaussian distribution
+    let s, a, b;
+    do
+    {
+        a = 2 * Math.random() - 1;
+        b = 2 * Math.random() - 1;
+        s = a * a + b * b;
+    }
+    while (s>=1 || s==0)
+    s = Math.sqrt(-2*Math.log(s) / s);
+    return [a * s, b * s];
 };
 
 /**
  * Attack the target entity. This should only be called after a successful range check,
  * and should only be called after GetTimers().repeat msec has passed since the last