changeset 180:90522b72128a trunk

[svn r196] Added C++ version of the ray demo for comparing.
author lindquist
date Wed, 07 May 2008 18:46:56 +0200
parents c853a8a04cdc
children ef4108f34db6
files demos/ray.cpp
diffstat 1 files changed, 124 insertions(+), 0 deletions(-) [+]
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/demos/ray.cpp	Wed May 07 18:46:56 2008 +0200
@@ -0,0 +1,124 @@
+#include <list>
+#include <iostream>
+#include <limits>
+#include <cmath>
+#include <cstdlib>
+
+using namespace std;
+
+numeric_limits<double> real;
+double delta = sqrt(real.epsilon()), infinity = real.infinity();
+
+struct Vec {
+  double x, y, z;
+  Vec(double x2, double y2, double z2) : x(x2), y(y2), z(z2) {}
+};
+Vec operator+(const Vec &a, const Vec &b)
+{ return Vec(a.x+b.x, a.y+b.y, a.z+b.z); }
+Vec operator-(const Vec &a, const Vec &b)
+{ return Vec(a.x-b.x, a.y-b.y, a.z-b.z); }
+Vec operator*(double a, const Vec &b) { return Vec(a*b.x, a*b.y, a*b.z); }
+double dot(const Vec &a, const Vec &b) { return a.x*b.x + a.y*b.y + a.z*b.z; }
+Vec unitise(const Vec &a) { return (1 / sqrt(dot(a, a))) * a; }
+
+typedef pair<double, Vec> Hit;
+
+struct Ray {
+  Vec orig, dir;
+  Ray(const Vec &o, const Vec &d) : orig(o), dir(d) {}
+};
+
+struct Scene {
+  virtual ~Scene() {};
+  virtual void intersect(Hit &, const Ray &) const = 0;
+};
+
+struct Sphere : public Scene {
+  Vec center;
+  double radius;
+
+  Sphere(Vec c, double r) : center(c), radius(r) {}
+  ~Sphere() {}
+
+  double ray_sphere(const Ray &ray) const {
+    Vec v = center - ray.orig;
+    double b = dot(v, ray.dir), disc = b*b - dot(v, v) + radius * radius;
+    if (disc < 0) return infinity;
+    double d = sqrt(disc), t2 = b + d;
+    if (t2 < 0) return infinity;
+    double t1 = b - d;
+    return (t1 > 0 ? t1 : t2);
+  }
+
+  void intersect(Hit &hit, const Ray &ray) const {
+    double lambda = ray_sphere(ray);
+    if (lambda >= hit.first) return;
+    hit = Hit(lambda, unitise(ray.orig + lambda*ray.dir - center));
+  }
+};
+
+typedef list<Scene *> Scenes;
+struct Group : public Scene {
+  Sphere bound;
+  Scenes child;
+
+  Group(Sphere b, Scenes c) : bound(b), child(c) {}
+  ~Group() {
+    for (Scenes::const_iterator it=child.begin(); it!=child.end(); ++it)
+      delete *it;
+  }
+
+  void intersect(Hit &hit, const Ray &ray) const {
+    double l = bound.ray_sphere(ray);
+    if (l < hit.first)
+      for (Scenes::const_iterator it=child.begin(); it!=child.end(); ++it)
+        (*it)->intersect(hit, ray);
+  }
+};
+
+Hit intersect(const Ray &ray, const Scene &s) {
+  Hit res = Hit(infinity, Vec(0, 0, 0));
+  s.intersect(res, ray);
+  return res;
+}
+
+double ray_trace(const Vec &light, const Ray &ray, const Scene &s) {
+  Hit hit = intersect(ray, s);
+  if (hit.first == infinity) return 0;
+  double g = dot(hit.second, light);
+  if (g >= 0) return 0.;
+  Vec p = ray.orig + hit.first*ray.dir + delta*hit.second;
+  return (intersect(Ray(p, -1. * light), s).first < infinity ? 0 : -g);
+}
+
+Scene *create(int level, const Vec &c, double r) {
+  Scene *s = new Sphere(c, r);
+  if (level == 1) return s;
+  Scenes child;
+  child.push_back(s);
+  double rn = 3*r/sqrt(12.);
+  for (int dz=-1; dz<=1; dz+=2)
+    for (int dx=-1; dx<=1; dx+=2)
+      child.push_back(create(level-1, c + rn*Vec(dx, 1, dz), r/2));
+  return new Group(Sphere(c, 3*r), child);
+}
+
+int main(int argc, char *argv[]) {
+  int level = 6, n = 512, ss = 4;
+  if (argc == 2) level = atoi(argv[1]);
+  Vec light = unitise(Vec(-1, -3, 2));
+  Scene *s(create(level, Vec(0, -1, 0), 1));
+  cout << "P5\n" << n << " " << n << "\n255\n";
+  for (int y=n-1; y>=0; --y)
+    for (int x=0; x<n; ++x) {
+      double g=0;
+      for (int dx=0; dx<ss; ++dx)
+        for (int dy=0; dy<ss; ++dy) {
+          Vec dir(unitise(Vec(x+dx*1./ss-n/2., y+dy*1./ss-n/2., n)));
+          g += ray_trace(light, Ray(Vec(0, 0, -4), dir), *s);
+        }
+      cout << char(int(.5 + 255. * g / (ss*ss)));
+    }
+  delete s;
+  return 0;
+}