Added set_face_normal function to src

Author: trevordblack

src/InOneWeekend/hittable.h

@@ -22,6 +22,11 @@ struct hit_record {
     material *mat_ptr;
     double t;
     bool front_face;
+
+    void set_face_normal(const ray& r, const vec3& outward_normal) {
+        front_face = dot(r.direction(), outward_normal) < 0;
+        normal = front_face ? outward_normal :-outward_normal;
+    }
 };
 
 class hittable {

src/TheNextWeek/hittable.h

@@ -33,6 +33,11 @@ struct hit_record {
     double u;
     double v;
     bool front_face;
+
+    void set_face_normal(const ray& r, const vec3& outward_normal) {
+        front_face = dot(r.direction(), outward_normal) < 0;
+        normal = front_face ? outward_normal :-outward_normal;
+    }
 };
 
 class hittable {

src/TheRestOfYourLife/hittable.h

@@ -33,6 +33,11 @@ struct hit_record {
     double u;
     double v;
     bool front_face;
+
+    void set_face_normal(const ray& r, const vec3& outward_normal) {
+        front_face = dot(r.direction(), outward_normal) < 0;
+        normal = front_face ? outward_normal :-outward_normal;
+    }
 };
 
 class hittable {