Added presentations from EVI 2017

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

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+#pragma once
+#ifndef FIGURE_HPP
+#define FIGURE_HPP
+
+#include <glm/vec3.hpp>
+
+#include "ray.hpp"
+#include "material.hpp"
+
+using glm::vec3;
+
+class Figure {
+public:
+  Material * m_mat;
+
+  Figure(Material * mat = NULL): m_inv_area(0.0f) {
+    m_mat = mat == NULL ? new Material() : mat;
+  }
+  
+  virtual ~Figure() {
+    delete m_mat;
+  }
+
+  virtual float pdf() const {
+    return m_inv_area;
+  }
+
+  virtual bool intersect(Ray & r, float & t) const = 0;
+  virtual vec3 normal_at_int(Ray & r, float & t) const = 0;
+  virtual vec3 sample_at_surface() const = 0;
+
+protected:
+  float m_inv_area;
+
+  virtual void calculate_inv_area() = 0;
+};
+
+#endif