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diff --git a/builtin_data/_pbr_fresnel_lookup.glsl b/builtin_data/_pbr_fresnel_lookup.glsl
new file mode 100644
index 00000000..0ba97072
--- /dev/null
+++ b/builtin_data/_pbr_fresnel_lookup.glsl
@@ -0,0 +1,43 @@
+import _pbr_prefilter;
+
+#pragma MSP stage(vertex)
+layout(location=0) in vec4 vertex;
+void main()
+{
+	gl_Position = vertex;
+	out vec2 texcoord = vertex.xy*0.5+0.5;
+}
+
+#pragma MSP stage(fragment)
+layout(location=0) out vec2 frag_out;
+void main()
+{
+	vec3 normal = vec3(0.0, 0.0, 1.0);
+	vec3 look_dir = vec3(sqrt(1.0-texcoord.y*texcoord.y), 0.0, -texcoord.y);
+	float roughness = texcoord.x;
+
+	float geom_k = roughness*roughness/2.0;
+	float geom_look = -look_dir.z/(geom_k-look_dir.z*(1.0-geom_k));
+
+	vec2 sum = vec2(0.0);
+	for(int i=0; i<n_samples; ++i)
+	{
+		vec3 halfway = ndist_ggxtr_importance_sample(hammersley(i, n_samples), roughness);
+		vec3 light_dir = reflect(look_dir, halfway);
+
+		if(light_dir.z>0)
+		{
+			float geom_light = light_dir.z/(geom_k+light_dir.z*(1.0-geom_k));
+			float geom = geom_look*geom_light;
+
+			// Look_dir points towards the surface, so the dot product is negated
+			float half_dot_look = dot(halfway, look_dir);
+			float ng = geom*half_dot_look/(halfway.z*look_dir.z);
+			float a = pow(max(1+half_dot_look, 0.0), 5.0);
+
+			sum += vec2(ng*(1-a), ng*a);
+		}
+	}
+
+	frag_out = sum/n_samples;
+}