From f8fc66247f2c678b3041e2da18724f699f68cfd2 Mon Sep 17 00:00:00 2001
From: brianharvey <bh@cs.berkeley.edu>
Date: Thu, 22 Apr 2021 21:55:31 -0700
Subject: [PATCH] fix negative color effect in objects.js

In JS, foo%360 gives a negative remainder if the dividend is negative.  This one-line change from developer.mozilla.org computes the correct modulo.
I should have called this branch "color" not "ghost", oops.
---
 src/objects.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/objects.js b/src/objects.js
index b47ed3bd..bb1b6678 100644
--- a/src/objects.js
+++ b/src/objects.js
@@ -5113,7 +5113,7 @@ SpriteMorph.prototype.applyGraphicsEffects = function (canvas) {
             }
             v = max / 255;
 
-            h = (h + hueShift * 360 / 200) % 360;
+            h = (((h + hueShift * 360 / 200) % 360)+360)%360;
             s = Math.max(0, Math.min(s + saturationShift / 100, 1));
             v = Math.max(0, Math.min(v + brightnessShift / 100, 1));