diff --git a/Effects/PBREffect.cs b/Effects/PBREffect.cs
index ba73003..852bde2 100644
--- a/Effects/PBREffect.cs
+++ b/Effects/PBREffect.cs
@@ -88,8 +88,14 @@ namespace Smuggler
             { 
                 world = value;
                 worldParam.SetValue(world);
-                worldViewProjectionParam.SetValue(world * view * projection);
-                worldInverseTransposeParam.SetValue(Matrix.Transpose(Matrix.Invert(world)));
+
+                Matrix.Multiply(ref world, ref view, out Matrix worldView);
+                Matrix.Multiply(ref worldView, ref projection, out Matrix worldViewProj);
+                worldViewProjectionParam.SetValue(worldViewProj);
+
+                Matrix.Invert(ref world, out Matrix worldInverse);
+                Matrix.Transpose(ref worldInverse, out Matrix worldInverseTranspose);
+                worldInverseTransposeParam.SetValue(worldInverseTranspose);
             }
         }
 
@@ -100,8 +106,13 @@ namespace Smuggler
             { 
                 view = value;
                 viewParam.SetValue(view);
-                worldViewProjectionParam.SetValue(world * view * projection);
-                eyePositionParam.SetValue(Matrix.Invert(view).Translation);
+
+                Matrix.Multiply(ref world, ref view, out Matrix worldView);
+                Matrix.Multiply(ref worldView, ref projection, out Matrix worldViewProj);
+                worldViewProjectionParam.SetValue(worldViewProj);          
+                
+                Matrix.Invert(ref view, out Matrix inverseView);
+                eyePositionParam.SetValue(inverseView.Translation);
             }
         }
 
@@ -112,7 +123,10 @@ namespace Smuggler
             { 
                 projection = value;
                 projectionParam.SetValue(projection);
-                worldViewProjectionParam.SetValue(world * view * projection);
+
+                Matrix.Multiply(ref world, ref view, out Matrix worldView);
+                Matrix.Multiply(ref worldView, ref projection, out Matrix worldViewProj);
+                worldViewProjectionParam.SetValue(worldViewProj);   
             }
         }
 
diff --git a/Effects/PBREffect.fx b/Effects/PBREffect.fx
index e26bd49..28dd3b5 100644
--- a/Effects/PBREffect.fx
+++ b/Effects/PBREffect.fx
@@ -52,10 +52,10 @@ struct PixelShaderInput
 PixelShaderInput main_vs(VertexShaderInput input)
 {
     PixelShaderInput output;
-
+   
     output.PositionWS = mul(input.Position, World).xyz;
     output.TexCoord = input.TexCoord;
-    output.NormalWS = normalize(mul(WorldInverseTranspose, input.Normal));
+    output.NormalWS = normalize(mul(input.Normal, (float3x3)WorldInverseTranspose));
 
     output.Position = mul(input.Position, WorldViewProjection);
     return output;
@@ -107,6 +107,9 @@ float4 None(PixelShaderInput input) : SV_TARGET
     float3 N = normalize(input.NormalWS);
     float3 V = normalize(EyePosition - input.PositionWS);
 
+    float3 F0 = float3(0.04, 0.04, 0.04);
+    F0 = lerp(F0, Albedo, Metallic);
+
     float3 Lo = float3(0.0, 0.0, 0.0);
 
     for (int i = 0; i < 4; i++)
@@ -119,12 +122,9 @@ float4 None(PixelShaderInput input) : SV_TARGET
         float attenuation = 1.0 / (distance * distance);
         float3 radiance = LightColors[i] * attenuation;
 
-        float3 F0 = float3(0.04, 0.04, 0.04);
-        F0 = lerp(F0, Albedo, Metallic);
-        float3 F = FresnelSchlick(max(dot(H, V), 0.0), F0);
-
         float NDF = DistributionGGX(N, H, Roughness);
         float G = GeometrySmith(N, V, L, Roughness);
+        float3 F = FresnelSchlick(max(dot(H, V), 0.0), F0);
 
         float3 numerator = NDF * G * F;
         float denominator = 4.0 * max(dot(N, V), 0.0) * max(dot(N, L), 0.0);
diff --git a/Effects/PBREffect.fxb b/Effects/PBREffect.fxb
index bcc23fa..2a7a43f 100644
Binary files a/Effects/PBREffect.fxb and b/Effects/PBREffect.fxb differ
diff --git a/Importer.cs b/Importer.cs
index 7f1b75c..ff13912 100644
--- a/Importer.cs
+++ b/Importer.cs
@@ -231,24 +231,24 @@ namespace Smuggler
             effect.AO = 1f;
 
             effect.Lights[0] = new PBRLight(
-                new Vector3(-10f, 10f, 10f),
+                new Vector3(-10f, 10f, -10f),
                 new Vector3(300f, 300f, 300f)
             );
 
-            effect.Lights[1] = new PBRLight(
-                new Vector3(10f, 10f, 10f),
-                new Vector3(300f, 300f, 300f)
-            );
+            // effect.Lights[1] = new PBRLight(
+            //     new Vector3(10f, 10f, 10f),
+            //     new Vector3(300f, 300f, 300f)
+            // );
 
-            effect.Lights[2] = new PBRLight(
-                new Vector3(-10f, -10f, 10f),
-                new Vector3(300f, 300f, 300f)
-            );
+            // effect.Lights[2] = new PBRLight(
+            //     new Vector3(-10f, -10f, 10f),
+            //     new Vector3(300f, 300f, 300f)
+            // );
 
-            effect.Lights[3] = new PBRLight(
-                new Vector3(10f, -10f, 10f), 
-                new Vector3(300f, 300f, 300f)
-            );
+            // effect.Lights[3] = new PBRLight(
+            //     new Vector3(10f, -10f, 10f), 
+            //     new Vector3(300f, 300f, 300f)
+            // );
 
             /* FIXME: how to load cube maps from GLTF? */
             /*