[FIX] the normal used for projecting the input vectors needs to be in object space.

src/modules/imageSpaceLIC/shaders/WMImageSpaceLIC-Transformation-fragment.glsl

@@ -145,7 +145,8 @@ void main()
     gl_FragData[1] = colormapping();
 
     // is the vector very orthogonal to the surface? We scale our advection according to this.
-    float dotS = abs( dot( v_normal, vec.xyz ) );
+    float dotS = abs( dot( v_normalObject, vec.xyz ) );
+    // scale down the vector -> the more it "comes out of the surface, the shorter the vector".
     vec2 dotScaled = ( 1.0 - dotS ) * scaleMaxToOne( vecProjected ).xy;
 
     gl_FragData[0] = vec4( vec2( 0.5 ) + ( 0.5  * dotScaled ), light, noise3D );

src/modules/imageSpaceLIC/shaders/WMImageSpaceLIC-Transformation-varyings.glsl

@@ -27,6 +27,11 @@
  */
 varying vec3 v_normal;
 
+/**
+ * Normal in object space
+ */
+varying vec3 v_normalObject;
+
 /**
  * The normal interpolated and projected to screenspace
  */

src/modules/imageSpaceLIC/shaders/WMImageSpaceLIC-Transformation-vertex.glsl

@@ -95,10 +95,11 @@ void main()
 
     // some light precalculations
     v_normal = gl_NormalMatrix * gl_Normal;
+    v_normalObject = gl_Normal;
 
     // NOTE: we normalize the vec here although we need to normalize it again in the fragment shader since the projected vector might be very
     // small and we want to avoid numerical issues when interpolating.
-    v_normalProjected = normalize( projectVector( vec4( gl_Normal.xyz, 0.0 ) ) );
+    v_normalProjected = normalize( projectVector( vec4( v_normal, 0.0 ) ) );
 
     // if we use 3d noise textures and auto resolution feature:
 #ifdef NOISE3D_ENABLED