commit 8376b7d11323b216cc28fae015ab3b5b7c32c052
Author: Leszek Koltunski <leszek@koltunski.pl>
Date:   Mon Jul 20 21:47:52 2020 +0100

    Fix the fact that Distort was rotating normals outside of its region!

diff --git a/src/main/java/org/distorted/library/effect/VertexEffectDistort.java b/src/main/java/org/distorted/library/effect/VertexEffectDistort.java
index 8e8805a..37ddbe2 100644
--- a/src/main/java/org/distorted/library/effect/VertexEffectDistort.java
+++ b/src/main/java/org/distorted/library/effect/VertexEffectDistort.java
@@ -131,27 +131,30 @@ public class VertexEffectDistort extends VertexEffect
       + "vec4 region= vUniforms[effect+2];                             \n"
       + "float d = degree(region,ps);                                  \n"
 
-      + "v += d*force;                                                 \n"
+      + "if( d>0.0 )                                                   \n"
+      + "  {                                                           \n"
+      + "  v += d*force;                                               \n"
 
-      + "float tp = 1.0+n.z;                                           \n"
-      + "float tr = 1.0 / (tp - (sign(tp)-1.0));                       \n"   // proper way to compute 1/x is
+      + "  float tp = 1.0+n.z;                                         \n"
+      + "  float tr = 1.0 / (tp - (sign(tp)-1.0));                     \n"   // proper way to compute 1/x is
                                                                              // 1/(x-(sign(x)-1)) and NOT 1/(x+1-sign(x))
 
-      + "float ap = ps.x*n.z - ps.z*n.x;                               \n"   // rotate the ps vector
-      + "float bp = ps.y*n.z - ps.z*n.y;                               \n"   //
-      + "float cp =(ps.x*n.y - ps.y*n.x)*tr;                           \n"   //
-      + "vec3 psRot = vec3( ap+n.y*cp , bp-n.x*cp , dot(ps,n) );       \n"   //
+      + "  float ap = ps.x*n.z - ps.z*n.x;                             \n"   // rotate the ps vector
+      + "  float bp = ps.y*n.z - ps.z*n.y;                             \n"   //
+      + "  float cp =(ps.x*n.y - ps.y*n.x)*tr;                         \n"   //
+      + "  vec3 psRot = vec3( ap+n.y*cp , bp-n.x*cp , dot(ps,n) );     \n"   //
 
-      + "float len = length(psRot);                                    \n"
-      + "float corr= sign(len)-1.0;                                    \n"   // make N (0,0,1) if ps=(0,0,0)
-      + "vec3 N = vec3( -dot(force,n)*psRot.xy, region.w*len-corr );   \n"   // modified rotated normal
+      + "  float len = length(psRot);                                  \n"
+      + "  float corr= sign(len)-1.0;                                  \n"   // make N (0,0,1) if ps=(0,0,0)
+      + "  vec3 N = vec3( -dot(force,n)*psRot.xy, region.w*len-corr ); \n"   // modified rotated normal
                                                                              // dot(force,n) is rotated force.z
-      + "float an = N.x*n.z + N.z*n.x;                                 \n"   // now create the normal vector
-      + "float bn = N.y*n.z + N.z*n.y;                                 \n"   // back from our modified normal
-      + "float cn =(N.x*n.y - N.y*n.x)*tr;                             \n"   // rotated back
-      + "n = vec3( an+n.y*cn , bn-n.x*cn , -N.x*n.x-N.y*n.y+N.z*n.z);  \n"   // notice 4 signs change!
+      + "  float an = N.x*n.z + N.z*n.x;                               \n"   // now create the normal vector
+      + "  float bn = N.y*n.z + N.z*n.y;                               \n"   // back from our modified normal
+      + "  float cn =(N.x*n.y - N.y*n.x)*tr;                           \n"   // rotated back
+      + "  n = vec3( an+n.y*cn , bn-n.x*cn , -N.x*n.x-N.y*n.y+N.z*n.z);\n"   // notice 4 signs change!
 
-      + "  n = normalize(n);                                           \n";
+      + "  n = normalize(n);                                           \n"
+      + "  }";
 
     }