From 82b612f0d39ad325ccd6f804783ca98053247e24 Mon Sep 17 00:00:00 2001
From: A1essandro <alexander.yermakov.1990@gmail.com>
Date: Mon, 16 May 2016 22:13:45 +0400
Subject: [PATCH] Improved logic of persistence

---
 demo/visual.php          | 2 +-
 src/DiamondAndSquare.php | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/demo/visual.php b/demo/visual.php
index 02cae10..9fe9ad1 100644
--- a/demo/visual.php
+++ b/demo/visual.php
@@ -6,7 +6,7 @@
 
 $size = 8;
 
-$gen->setPersistence(200);
+$gen->setPersistence(1.8);
 $gen->setSize($size);
 $gen->setMapSeed(uniqid());
 $map = $gen->generate();
diff --git a/src/DiamondAndSquare.php b/src/DiamondAndSquare.php
index 6ca57b0..5843342 100644
--- a/src/DiamondAndSquare.php
+++ b/src/DiamondAndSquare.php
@@ -242,7 +242,9 @@ private function diamond($x, $y, $size, $offset)
      */
     private function getOffset($stepSize)
     {
-        return (float)$stepSize / $this->size * mt_rand(-$this->getPersistence() / 2, $this->getPersistence() / 2);
+        $stepOffset = $stepSize / $this->size * mt_rand(-$this->size, $this->size);
+        $sign = $stepOffset < 0 ? -1 : 1;
+        return $sign * pow(abs($stepOffset), 1 / sqrt($this->getPersistence()));
     }
 
     /**