From 160e881ba74a6b734000c75c614a830c82346491 Mon Sep 17 00:00:00 2001
From: tuxmain <tuxmain@zettascript.org>
Date: Mon, 29 Aug 2022 09:54:23 +0200
Subject: [PATCH] fix: allow negative values for rotating filter

---
 src/filters.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/filters.rs b/src/filters.rs
index 9a18af2..7596677 100644
--- a/src/filters.rs
+++ b/src/filters.rs
@@ -23,6 +23,10 @@ impl PassThroughFilter {
 			PassThroughFilter::Rotating(filter_angle) => {
 				let mut hsla = color.as_hsla_f32();
 				hsla[0] = (hsla[0] + filter_angle) % 360.;
+				// floating rem is not modulo!
+				if hsla[0] < 0. {
+					hsla[0] += 360.;
+				}
 				Color::hsla(hsla[0], hsla[1], hsla[2], hsla[3])
 			}
 		}