Added presentations from EVI 2017

EVI - 2017/EVI 21/EVIray/sampling.hpp

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+#pragma once
+#ifndef SAMPLING_HPP
+#define SAMPLING_HPP
+
+#include <glm/vec2.hpp>
+#include <glm/vec3.hpp>
+
+using glm::vec2;
+using glm::vec3;
+
+extern const float PDF;
+
+extern float random01();
+extern vec2 sample_pixel(int i, int j, float w, float h, float a_ratio, float fov);
+extern void create_coords_system(const vec3 &n, vec3 &nt, vec3 &nb);
+extern vec3 sample_hemisphere(const float r1, float r2);
+extern void rotate_sample(vec3 & sample, const vec3 & n);
+extern vec3 sample_sphere(const vec3 center, const float radius);
+
+#endif