What if the ray is perpendicular to the normal vector and the line is ON the plane? What would the value of t be in this case?

WolfLink

In that case, t does not have a well defined value, because any value of t would result in a point on the plane. If you really needed to handle a case like this, you would probably have to detect the situation and use another algorithm for a ray-line intersection on the bounding edge of the face that is contained by the plane. However, I you would generally not need to worry about this because due to randomly generated rays, extremely specific cases like that will statistically never happen.

What if the ray is perpendicular to the normal vector and the line is ON the plane? What would the value of t be in this case?

In that case, t does not have a well defined value, because any value of t would result in a point on the plane. If you really needed to handle a case like this, you would probably have to detect the situation and use another algorithm for a ray-line intersection on the bounding edge of the face that is contained by the plane. However, I you would generally not need to worry about this because due to randomly generated rays, extremely specific cases like that will statistically never happen.