gistfile1.cpp

#include "algebra3.h"
#include <iostream>
#include <cmath>

using namespace std;

static inline bool refract(const vec3& N, const vec3& I, const double n1, const double n2, vec3& result) {
  double n = n1 / n2;
  double cosI = -(N * I);
  double sinT2 = n * n * ( 1.0 - cosI * cosI );
  if (sinT2 > 1.0) return false;
  double cosT = sqrt( 1.0 - sinT2 );
  result = n * I + ( n * cosI - cosT ) * N;
  return true;
}

static inline bool refract0(const vec3& N, const vec3& I, const double n1, const double n2, vec3& result) {
  double dDotN = I * N;
  double cosPhiSq = 1.0 - n1 * n1 * ( 1.0 - dDotN * dDotN ) / ( n2 * n2 );
  if (cosPhiSq < 0) return false;
  result = ( n1 * ( I - ( N * dDotN ) ) / n2 ) - ( N * sqrt(cosPhiSq) );
  return true;
}

int main(int argc, char **argv) {
  vec3 I(0.707107, -0.707107, 0.0);
  vec3 N(0, 1, 0);
  double n2 = 1.333;
  double n1 = 0.9 * n2;
  vec3 T1;

  if (refract(N, I, n1, n2, T1)) {
    cout << "Success. T = " << T1 << endl;
  } else
    cout << "Failure" << endl;

  vec3 T2;

  if (refract0(N, I, n1, n2, T2)) {
    cout << "Success. T = " << T2 << endl;
  } else
    cout << "Failure" << endl;


  return 0;
}