diff --git a/src/surface.c b/src/surface.c
index c87daa5..3e4aaa3 100644
--- a/src/surface.c
+++ b/src/surface.c
@@ -165,17 +165,10 @@ static void __calculate_normal(
     u2 = malloc(n * sizeof(float));
     u3 = malloc(n * sizeof(float));
 
-    switch (n)
+    /* 
+    	Calculate a normal vector of a plain using Gram-Schmidt process
+    */
     {
-    case 3:
-        glm_vec3_sub(p2, p1, v1);
-        glm_vec3_sub(p3, p1, v2);
-
-        glm_vec3_cross(v1, v2, normal);
-        glm_vec3_normalize(normal);
-        return;
-
-    default:
         for (i = 0; i < n; ++i) {
             v1[i] = p2[i] - p1[i];  
             v2[i] = p3[i] - p1[i]; 
@@ -267,4 +260,4 @@ float *generate_normals_surface(float *d, unsigned char m)
 
 	free(norm_vec);
 	return n;
-}
\ No newline at end of file
+}