camera.h

#ifndef CAMERAH
#define CAMERAH

#include "ray.h"

vec3 randomInUnitDisk() {
  vec3 p;
  do {
    p = 2.0*vec3(drand48(),drand48(),0) - vec3(1,1,0);
  } while(dot(p,p) >= 1.0);
  return p;
}

class camera {
public:
  camera(vec3 lookFrom, vec3 lookAt, vec3 vUp, double vfov, double aspect, double aperature, double focusDist) {
    lensRadius = aperature/2;
    double theta = vfov*M_PI/180;
    double halfHeight = tan(theta/2);
    double halfWidth = aspect*halfHeight;
    origin = lookFrom;
    w = unitVector(lookFrom - lookAt);
    u = unitVector(cross(vUp, w));
    v = cross(w, u);
    lowerLeftCorner = origin - halfWidth*focusDist*u - halfHeight*focusDist*v - focusDist*w;
    horizontal = 2*halfWidth*focusDist*u;
    vertical = 2*halfHeight*focusDist*v;
  }

  ray getRay(double s, double t) {
    vec3 rd = lensRadius*randomInUnitDisk();
    vec3 offset = u*rd.x() + v*rd.y();
    return ray(origin+offset, lowerLeftCorner + s*horizontal + t*vertical - origin - offset);
  }

  vec3 origin;
  vec3 lowerLeftCorner;
  vec3 horizontal;
  vec3 vertical;
  vec3 u, v, w;
  double lensRadius;
};

#endif