diff --git a/data/shader/phong.fsh b/data/shader/phong.fsh
index 53ae944..154ee93 100644
--- a/data/shader/phong.fsh
+++ b/data/shader/phong.fsh
@@ -60,11 +60,11 @@ vec2 poissonDisk[16] = vec2[](
    vec2( 0.14383161, -0.14100790 )
 );
 
-float sampleDirectionalShadow(sampler2DShadow shadowMap, vec4 shadowCoord) {
+float sampleDirectionalShadow(sampler2DShadow shadowMap, vec4 shadowCoord, float maxBias ) {
     float visibility = 1.0;
     const float stretching = 650.0;
     float bias = 0.001*tan(acos(clamp(dot(vNormal, -directionalLightVector), 0.0, 1.0)));
-    bias = clamp(bias, 0.0, 0.01);
+    bias = clamp(bias, 0.0, maxBias);
     for (int i=0; i<4; i++) {
         visibility -= directionalIntensity/16*(1.0-texture(shadowMap, vec3(shadowCoord.xy + poissonDisk[i]/stretching, shadowCoord.z - bias)));
     }
@@ -109,24 +109,24 @@ void main()
         float directionalVisibility = 1.0f;
         if (distanceToBorder(shadowCoord1.xy) <= 0.5 && distanceToBorder(shadowCoord1.xy) > 0.2) {
             if (distanceToBorder(shadowCoord0.xy) <= 0.5 && distanceToBorder(shadowCoord0.xy) > 0.2) {
-                directionalVisibility = sampleDirectionalShadow(shadowMap_directional0, shadowCoord0);
+                directionalVisibility = sampleDirectionalShadow(shadowMap_directional0, shadowCoord0, 0.001);
             }
             else if (distanceToBorder(shadowCoord0.xy) <= 0.5 && distanceToBorder(shadowCoord0.xy) > 0.0) {
-                float directionalVisibility0 = sampleDirectionalShadow(shadowMap_directional0, shadowCoord0);
-                float directionalVisibility1 = sampleDirectionalShadow(shadowMap_directional1, shadowCoord1);
+                float directionalVisibility0 = sampleDirectionalShadow(shadowMap_directional0, shadowCoord0, 0.001);
+                float directionalVisibility1 = sampleDirectionalShadow(shadowMap_directional1, shadowCoord1, 0.002);
                 directionalVisibility = mix(directionalVisibility0, directionalVisibility1, distanceToBorder(shadowCoord0.xy) * 5);
             }
             else {
-                directionalVisibility = sampleDirectionalShadow(shadowMap_directional1, shadowCoord1);
+                directionalVisibility = sampleDirectionalShadow(shadowMap_directional1, shadowCoord1, 0.002);
             }
         }
         else if (distanceToBorder(shadowCoord1.xy) <= 0.5 && distanceToBorder(shadowCoord1.xy) > 0.0) {
-            float directionalVisibility1 = sampleDirectionalShadow(shadowMap_directional1, shadowCoord1);
-            float directionalVisibility2 = sampleDirectionalShadow(shadowMap_directional2, shadowCoord2);
+            float directionalVisibility1 = sampleDirectionalShadow(shadowMap_directional1, shadowCoord1, 0.01);
+            float directionalVisibility2 = sampleDirectionalShadow(shadowMap_directional2, shadowCoord2, 0.01);
             directionalVisibility = mix(directionalVisibility1, directionalVisibility2, distanceToBorder(shadowCoord1.xy) * 5);
         }
         else {
-            directionalVisibility = sampleDirectionalShadow(shadowMap_directional2, shadowCoord2);
+            directionalVisibility = sampleDirectionalShadow(shadowMap_directional2, shadowCoord2, 0.01);
         }
         diffuseColor += clamp(dot(normalize(vNormal), directionalVector)
         *diffuseFactor*directionalIntensity*directionalColor, 0.0, 1.0)*directionalVisibility;