commit 30d07491049f5ab391f5b75422aa254c72663273
Author: Leszek Koltunski <leszek@koltunski.pl>
Date:   Mon Apr 27 20:59:08 2020 +0100

    bugfix for VertexEffectRotate

diff --git a/src/main/java/org/distorted/library/effect/VertexEffectRotate.java b/src/main/java/org/distorted/library/effect/VertexEffectRotate.java
index 7f04aba..1e98524 100644
--- a/src/main/java/org/distorted/library/effect/VertexEffectRotate.java
+++ b/src/main/java/org/distorted/library/effect/VertexEffectRotate.java
@@ -77,7 +77,7 @@ public class VertexEffectRotate extends VertexEffect
              + "float qz = vUniforms[effect].w * sinHalf;      \n"
              + "float qw = cosHalf;                            \n"
 
-             + "v += center;                                   \n"
+             + "v -= center;                                   \n"
 
              + "float tx = qx - v.z*qy + v.y*qz + v.x*qw;      \n"
              + "float ty = qy + v.z*qx + v.y*qw - v.x*qz;      \n"
@@ -88,7 +88,7 @@ public class VertexEffectRotate extends VertexEffect
              + "v.y = qw*ty - qz*tx - qy*tw + qx*tz;           \n"
              + "v.z = qw*tz - qz*tw + qy*tx - qx*ty;           \n"
 
-             + "v -= center;                                   \n"
+             + "v += center;                                   \n"
 
              + "float nx =  - n.z*qy + n.y*qz + n.x*qw;        \n"
              + "float ny =  + n.z*qx + n.y*qw - n.x*qz;        \n"