Sampler类定义

此是所有采样的基类，这样定义的好处是，我们可以分别测试每一个采样算法。

类定义：

#pragma once
#ifndef __SAMPLER_HEADER__
#define __SAMPLER_HEADER__

#include "../utilities/geometry.h"

class Sampler {
public:
	Sampler();
	virtual ~Sampler();
	Sampler(const integer samps);
	Sampler(const integer samps, const integer sets);
	Sampler(const Sampler& s);
	virtual Sampler* clone() const = 0;
	virtual void generate_samples() = 0;//这个设置为纯虚函数，书中没有这样做，我们这样做是方便之后动态调整采样数量
      virtual Point3 sample_unit_square();
	void setup_shuffled_indices();
	void set_num_sets(const integer sets);
	integer get_num_sets() const;
	void set_num_samples(const integer samps);
	integer get_num_samples() const;
	void clear();
	Sampler& operator=(const Sampler& s);
protected:
	integer nsamples;
	integer nsets;
	std::vector<Point3> samples;//这里采用Point3，兼容所有的采样算法
	std::vector<integer> shuffled_indices;
	integer count;
	integer jump;
};
#endif

　　

类实现：

#include "pch.h"
#include "sampler.h"

Sampler::Sampler() :nsamples(16), nsets(36), count(0), jump(0) {
	setup_shuffled_indices();
}

Sampler::~Sampler() {}

Sampler::Sampler(const integer samps) : nsamples(samps), nsets(36), count(0), jump(0) {
	setup_shuffled_indices();
}

Sampler::Sampler(const integer samps, const integer sets)
	: nsamples(samps), nsets(sets), count(0), jump(0) {
	setup_shuffled_indices();
}

Sampler::Sampler(const Sampler& s)
	: nsamples(s.nsamples), nsets(s.nsets), count(s.count), jump(s.jump),
	samples(s.samples), shuffled_indices(s.shuffled_indices) {}

Point3 Sampler::sample_unit_square() {
	if (count % nsamples == 0)
		jump = (random_integer() % nsets) * nsamples;
	return (samples[jump + shuffled_indices[jump + count++ % nsamples]]);
}

void Sampler::setup_shuffled_indices() {
	shuffled_indices.reserve(nsamples * nsets);
	std::vector<integer> indices;
	for (integer i = 0; i < nsamples; i++)
		indices.push_back(i);
	for (integer i = 0; i < nsets; i++) {
		random_shuffle(indices.begin(), indices.end());
		shuffled_indices.insert(shuffled_indices.end(), indices.begin(), indices.end());
	}
}

void Sampler::set_num_sets(const integer sets) {
	nsets = sets;
}

integer Sampler::get_num_sets() const {
	return nsets;
}

void Sampler::set_num_samples(const integer samps) {
	nsamples = samps;
}

integer Sampler::get_num_samples() const {
	return nsamples;
}

void Sampler::clear() {
	shuffled_indices.resize(0);
	samples.resize(0);
	count = jump = 0;
}

Sampler& Sampler::operator=(const Sampler& s) {
	if (this == &s)
		return *this;
	nsamples = s.nsamples;
	nsets = s.nsets;
	count = s.count;
	jump = s.jump;
	samples = s.samples;
	shuffled_indices = s.shuffled_indices;
	return *this;
}