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annotate demos/ray.cpp @ 1638:0de4525a9ed6

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Apply workaround for #395 by klickverbot.
author Christian Kamm <kamm incasoftware de>
date Mon, 08 Mar 2010 20:06:08 +0100
parents 90522b72128a
children
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1 #include <list>
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2 #include <iostream>
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3 #include <limits>
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4 #include <cmath>
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5 #include <cstdlib>
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6
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7 using namespace std;
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8
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9 numeric_limits<double> real;
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10 double delta = sqrt(real.epsilon()), infinity = real.infinity();
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11
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12 struct Vec {
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13 double x, y, z;
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14 Vec(double x2, double y2, double z2) : x(x2), y(y2), z(z2) {}
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15 };
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16 Vec operator+(const Vec &a, const Vec &b)
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17 { return Vec(a.x+b.x, a.y+b.y, a.z+b.z); }
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18 Vec operator-(const Vec &a, const Vec &b)
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19 { return Vec(a.x-b.x, a.y-b.y, a.z-b.z); }
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20 Vec operator*(double a, const Vec &b) { return Vec(a*b.x, a*b.y, a*b.z); }
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21 double dot(const Vec &a, const Vec &b) { return a.x*b.x + a.y*b.y + a.z*b.z; }
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22 Vec unitise(const Vec &a) { return (1 / sqrt(dot(a, a))) * a; }
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23
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24 typedef pair<double, Vec> Hit;
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25
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26 struct Ray {
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27 Vec orig, dir;
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28 Ray(const Vec &o, const Vec &d) : orig(o), dir(d) {}
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29 };
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30
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31 struct Scene {
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32 virtual ~Scene() {};
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33 virtual void intersect(Hit &, const Ray &) const = 0;
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34 };
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35
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36 struct Sphere : public Scene {
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37 Vec center;
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38 double radius;
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39
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40 Sphere(Vec c, double r) : center(c), radius(r) {}
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41 ~Sphere() {}
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42
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43 double ray_sphere(const Ray &ray) const {
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44 Vec v = center - ray.orig;
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45 double b = dot(v, ray.dir), disc = b*b - dot(v, v) + radius * radius;
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46 if (disc < 0) return infinity;
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47 double d = sqrt(disc), t2 = b + d;
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48 if (t2 < 0) return infinity;
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49 double t1 = b - d;
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50 return (t1 > 0 ? t1 : t2);
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51 }
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52
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53 void intersect(Hit &hit, const Ray &ray) const {
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54 double lambda = ray_sphere(ray);
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55 if (lambda >= hit.first) return;
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56 hit = Hit(lambda, unitise(ray.orig + lambda*ray.dir - center));
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57 }
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58 };
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59
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60 typedef list<Scene *> Scenes;
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61 struct Group : public Scene {
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62 Sphere bound;
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63 Scenes child;
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64
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65 Group(Sphere b, Scenes c) : bound(b), child(c) {}
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66 ~Group() {
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67 for (Scenes::const_iterator it=child.begin(); it!=child.end(); ++it)
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68 delete *it;
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69 }
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70
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71 void intersect(Hit &hit, const Ray &ray) const {
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72 double l = bound.ray_sphere(ray);
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73 if (l < hit.first)
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74 for (Scenes::const_iterator it=child.begin(); it!=child.end(); ++it)
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75 (*it)->intersect(hit, ray);
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76 }
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77 };
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78
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79 Hit intersect(const Ray &ray, const Scene &s) {
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80 Hit res = Hit(infinity, Vec(0, 0, 0));
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81 s.intersect(res, ray);
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82 return res;
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83 }
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84
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85 double ray_trace(const Vec &light, const Ray &ray, const Scene &s) {
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86 Hit hit = intersect(ray, s);
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87 if (hit.first == infinity) return 0;
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88 double g = dot(hit.second, light);
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89 if (g >= 0) return 0.;
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90 Vec p = ray.orig + hit.first*ray.dir + delta*hit.second;
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91 return (intersect(Ray(p, -1. * light), s).first < infinity ? 0 : -g);
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92 }
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93
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94 Scene *create(int level, const Vec &c, double r) {
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95 Scene *s = new Sphere(c, r);
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96 if (level == 1) return s;
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97 Scenes child;
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98 child.push_back(s);
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99 double rn = 3*r/sqrt(12.);
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100 for (int dz=-1; dz<=1; dz+=2)
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101 for (int dx=-1; dx<=1; dx+=2)
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102 child.push_back(create(level-1, c + rn*Vec(dx, 1, dz), r/2));
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103 return new Group(Sphere(c, 3*r), child);
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104 }
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105
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106 int main(int argc, char *argv[]) {
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107 int level = 6, n = 512, ss = 4;
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108 if (argc == 2) level = atoi(argv[1]);
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109 Vec light = unitise(Vec(-1, -3, 2));
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110 Scene *s(create(level, Vec(0, -1, 0), 1));
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111 cout << "P5\n" << n << " " << n << "\n255\n";
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112 for (int y=n-1; y>=0; --y)
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113 for (int x=0; x<n; ++x) {
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114 double g=0;
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115 for (int dx=0; dx<ss; ++dx)
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116 for (int dy=0; dy<ss; ++dy) {
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117 Vec dir(unitise(Vec(x+dx*1./ss-n/2., y+dy*1./ss-n/2., n)));
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118 g += ray_trace(light, Ray(Vec(0, 0, -4), dir), *s);
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119 }
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120 cout << char(int(.5 + 255. * g / (ss*ss)));
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121 }
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122 delete s;
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123 return 0;
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124 }