Algorithm incorrectly says ray intersects triangle above it - c

Question

This is one of many similar ray-triangle intersection algorithms. Every other algorithm I've tested also returns true for these numbers, while the ray clearly does not cross the triangle. The ray goes from y=0 to y=1, while the triangle is flat across y = 2.3.
This is not a winding issue, as it should never return true (winding issues would explain false negatives, not false positives).
All code necessary to reproduce in C or C++ is included here.
What am I missing?
#define vector(a,b,c) \
(a)[0] = (b)[0] - (c)[0]; \
(a)[1] = (b)[1] - (c)[1]; \
(a)[2] = (b)[2] - (c)[2];
#define crossProduct(a,b,c) \
(a)[0] = (b)[1] * (c)[2] - (c)[1] * (b)[2]; \
(a)[1] = (b)[2] * (c)[0] - (c)[2] * (b)[0]; \
(a)[2] = (b)[0] * (c)[1] - (c)[0] * (b)[1];
#define innerProduct(v,q) \
((v)[0] * (q)[0] + \
(v)[1] * (q)[1] + \
(v)[2] * (q)[2])
#define DOT(A,B) \
((A)[0] * (B)[0] + (A)[1] * (B)[1] + (A)[2] * (B)[2])
int intersect3D_RayTriangle( )
{
// dir, w0, w; // ray vectors
double r, a, b; // params to calc ray-plane intersect
// output: Point* I
//Ray R
double origin[3] = {0,0,0};//{orig[0],orig[1],orig[2]};
double direction[3] = {0,1,0};//{dir[0],dir[1],dir[2]};
//Triangle T
double corner1[3] = {3, 2.3, -4 };//{v0[0],v0[1],v0[2]};
double corner2[3] = {-7, 2.3, 2};//{v1[0],v1[1],v1[2]};
double corner3[3] = {3, 2.3, 2};// v2[0],v2[1],v2[2]};
// Vector u, v, n; // triangle vectors
double u[3] = {corner2[0]-corner1[0],corner2[1]-corner1[1],corner2[2]-corner1[2]};
double v[3] = {corner3[0]-corner1[0],corner3[1]-corner1[1],corner3[2]-corner1[2]};
double n[3] = {0,0,0};
double e1[3],e2[3],h[3],q[3];
double f;
// get triangle edge vectors and plane normal
crossProduct(n, u, v);
if ((n[0] == 0) && (n[1] == 0) && (n[2] == 0)) // triangle is wonky
return -1; // do not deal with this case
// dir = R.P1 - R.P0; // ray direction vector
double rayDirection[3] = {direction[0] - origin[0], direction[1] - origin[1], direction[2] - origin[2]};
//w0 = R.P0 - T.V0;
double w0[3] = {origin[0] - corner1[0], origin[1] - corner1[1], origin[2] - corner1[2]};
a = -DOT(n,w0);
b = DOT(n,rayDirection);
if (fabs(b) < __DBL_EPSILON__) { // ray is parallel to triangle plane
if (a == 0) // ray lies in triangle plane
return 2;
else return 0; // ray disjoint from plane
}
// get intersect point of ray with triangle plane
r = a / b;
if (r < 0.0) // ray goes away from triangle
return 0; // => no intersect
// for a segment, also test if (r > 1.0) => no intersect
//*I = R.P0 + r * dir; // intersect point of ray and plane
double I[3] = {0,0,0};
I[0] = origin[0] + rayDirection[0] * r;
I[1] = origin[1] + rayDirection[1] * r;
I[2] = origin[2] + rayDirection[2] * r;
// is I inside T?
double uu, uv, vv, wu, wv, D;
uu = DOT(u,u);
uv = DOT(u,v);
vv = DOT(v,v);
double w[3] = {0,0,0};
w[0] = I[0] - corner1[0];
w[1] = I[1] - corner1[1];
w[2] = I[2] - corner1[2];
wu = DOT(w,u);
wv = DOT(w,v);
D = uv * uv - uu * vv;
// get and test parametric coords
double s, t;
s = (uv * wv - vv * wu) / D;
if (s < 0.0 || s > 1.0) // I is outside T
return 0;
t = (uv * wu - uu * wv) / D;
if (t < 0.0 || (s + t) > 1.0) // I is outside T
return 0;
return 1; // I is in T
}

Answer 1

Code works fine for "rays".
OP expected that that "ray" code functioned like a "segment" one.
Could use the r value to testing for "segment" exclusion.
if (r > 1.0) return 0;