Book 3 Ch. 8.3 Listing 29: forgot to remove `pdf_value = scattering_pdf;`

[nicoverhart]

It was forgotten to remove pdf_value = scattering_pdf; in listing 29.

In listing 29 pdf_value is added as an argument in the call to rec.mat->scatter(), but the value of pdf_value set by that call is never used, because a few lines below pdf_value is set to scattering_pdf. As a result the changes to material::scatter() introduced in listing 28 are not actually used. Removing pdf_value = scattering_pdf; from listing 29, would resolve that problem. Or, even better, highlight double pdf_value = scattering_pdf; in red to mark it for removal relative to listing 21 (or listing 19).

raytracing.github.io/books/RayTracingTheRestOfYourLife.html

Lines 2408 to 2441 in 4dbfa6f

	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++
	class camera {
	...
	private:
	...
	color ray_color(const ray& r, int depth, const hittable& world) const {
	...
	ray scattered;
	color attenuation;
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++ highlight
	double pdf_value;
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++
	color color_from_emission = rec.mat->emitted(rec.u, rec.v, rec.p);
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++ highlight
	if (!rec.mat->scatter(r, rec, attenuation, scattered, pdf_value))
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++
	return color_from_emission;
	double scattering_pdf = rec.mat->scattering_pdf(r, rec, scattered);
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++ highlight
	pdf_value = scattering_pdf;
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++
	...
	}
	...
	};
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	[Listing [scatter-ray-color]: <kbd>[camera.h]</kbd> Updated ray_color function with returned PDF value]

This may relate to issue #1543.