Merge pull request #638 from RayTracing/book2-img-updates

Book2 img updates

Author: hollasch

books/RayTracingTheNextWeek.html

@@ -18,14 +18,6 @@
 
 class material;
 
-void get_sphere_uv(const point3& p, double& u, double& v) {
-    auto phi = atan2(p.z(), p.x());
-    auto theta = asin(p.y());
-    u = 1-(phi + pi) / (2*pi);
-    v = (theta + pi/2) / pi;
-}
-
-
 struct hit_record {
     point3 p;
     vec3 normal;