Book2: Listing 70: fuzz value and include bvh.h

[estshorter]

• bvh.h should be included as it usesbvh_node.
• Fuzz value for the metal sphere is set to 10.0, but 1.0 would be better, which is the maximum value.

raytracing.github.io/books/RayTracingTheNextWeek.html

Lines 3279 to 3281 in 7b92650

	objects.add(make_shared<sphere>(
	point3(0, 150, 145), 50, make_shared<metal>(color(0.8, 0.8, 0.9), 10.0)
	));

raytracing.github.io/src/TheNextWeek/material.h

Line 60 in 7b92650

metal(const color& a, double f) : albedo(a), fuzz(f < 1 ? f : 1) {}

[hollasch]

Fixed in #708