#include <iostream>
using namespace std;

#define EPSILON 0.000001
#define CROSS(dest,v1,v2); \
       dest[0]=v1[1]*v2[2]-v1[2]*v2[1]; \
       dest[1]=v1[2]*v2[0]-v1[0]*v2[2]; \
       dest[2]=v1[0]*v2[1]-v1[1]*v2[0];

#define DOT(v1,v2) ( v1[0]*v2[0]+v1[1]*v2[1]+v1[2]*v2[2])
#define SUB(dest,v1,v2) \
       dest[0]=v1[0]-v2[0]; \
       dest[1]=v1[1]-v2[1]; \
       dest[2]=v1[2]-v2[2];

int intersect_triangle(double orig[3], double dir[3], double vert0[3], double vert1[3], double vert2[3]);
int main() {

double origin[3] = {1.4,10.0,0.0};
double direction[3] = {0.0,-1.0,0.0};
double vertex0[3] = {1.0,0.0,0.0};
double vertex1[3] = {1.5,2.0,0.0};
double vertex2[3] = {2.0,0.0,0.0};

cout << intersect_triangle( origin, direction, vertex0, vertex1, vertex2);


return 0;
}

int intersect_triangle(double orig[3], double dir[3], double vert0[3], double vert1[3], double vert2[3])
{
  double *t = NULL, *u = NULL, *v = NULL;
  double edge1[3], edge2[3], tvec[3], pvec[3], qvec[3];
  double det, inv_det;

  // find vectors for two edges sharing vert0
  SUB(edge1, vert1, vert0);
  SUB(edge2, vert2, vert0);

  // begin calculation determinant - also used to calculate U parameter
  CROSS(pvec, dir, edge2);
 
  // if determinant is near zero, ray lies in plane of triangle
  det = DOT(edge1, pvec);

  if (det < EPSILON)
    return 0;

  // calculate distance from vert0 to ray origin
  SUB(tvec, orig, vert0);

  // calculate U parameter and test bounds
  *u = DOT(tvec, pvec);
  if (*u < 0.0 || *u > det)
    return 0;

  // prepare to test V parameter
  CROSS(qvec, tvec, edge1);

  // calculate V parameter and test bounds
  *v = DOT(dir, qvec);
  if (*v < 0.0 || *u + *v > det)
    return 0;

  // calculate t, scale parameters, ray intersects triangle
  *t = DOT(edge2, qvec);
  inv_det = 1.0 / det;
  *t *= inv_det;
  *u *= inv_det;
  *v *= inv_det;

  return 1;
}

0