diff --git a/orx-fx/src/shaders/glsl/edges/contour.frag b/orx-fx/src/shaders/glsl/edges/contour.frag
index 25a75945..7df091cb 100644
--- a/orx-fx/src/shaders/glsl/edges/contour.frag
+++ b/orx-fx/src/shaders/glsl/edges/contour.frag
@@ -7,11 +7,12 @@ uniform float contourOpacity;
 uniform vec4 contourColor;
 uniform float backgroundOpacity;
 uniform int window;
+uniform float bias;
 
 float calc_contour(vec2 uv) {
     vec4 box = texture(tex0, uv);
-    float v = sin(3.1415926535 * levels * dot(vec3(1.0/3.0),box.xyz));
-    float level = floor(dot(vec3(1.0/3.0),box.xyz) * levels) / levels;
+    float v = sin(3.1415926535 * levels * (dot(vec3(1.0 / 3.0), box.xyz) + bias));
+    float level = floor((dot(vec3(1.0 / 3.0), box.xyz) + bias) * levels) / levels;
     float contour = 1.0 - smoothstep(0., contourWidth, 0.5 * abs(v) / fwidth(v));
     return contour;
 }
@@ -21,13 +22,13 @@ void main() {
     float contour = 0.0;
     float weight = 0.0;
 
-     for (int i = -window; i <= window; ++i) {
+    for (int i = -window; i <= window; ++i) {
         for (int j = -window; j <= window; ++j) {
-            contour += calc_contour(v_texCoord0 + step/(float(window)+1.0) * vec2(float(i), float(j)));
+            contour += calc_contour(v_texCoord0 + step / (float(window) + 1.0) * vec2(float(i), float(j)));
             weight += 1.0;
         }
     }
     contour /= weight;
     vec4 t = texture(tex0, v_texCoord0);
-    o_output = t * backgroundOpacity * (1.0-contour) + contour * contourColor * contourOpacity * t.a;
+    o_output = t * backgroundOpacity * (1.0 - contour) + contour * contourColor * contourOpacity * t.a;
 }
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