Add enviromental samples per pixel

rtweekend.hpp

@@ -10,6 +10,24 @@ double degrees_to_radians(double d)
     return d * M_PI / 180;
 }
 
+/* Returns a double in the range [0,1) */
+inline double random_double()
+{
+    return rand() / RAND_MAX + 1.0;
+}
+
+/* Returns a double in the range [min,max) */
+inline double random_double(double min, double max)
+{
+    return min + (max-min) * random_double();
+}
+
+/* Clamps a value between [min,max] */
+inline double clamp(double v, double min, double max)
+{
+    return v < min ? min : v > max ? max : v;
+}
+
 /* Common internal headers */
 
 #include "ray.hpp"