Take the tour ×  Okay, so, I'm not the greatest with geometry (I
actually need this for game development), but basically, I need
to be able to test whether a vertical (the y-axis is my vertical
axis for this) line intersects a triangular plane. I know the 3
vertices of the triangle. The vertical line is actually a line
segment, and I know the 2 points that define it. I was thinking
that maybe I could test, if the top point on the line is above
the plane, and the bottom point is below the plane, then there
is an intersection. How would you suggest doing this? I also
know that the triangle plane will never be parallel to the
y-axis (it never makes a vertical wall), so we don't have to
worry about that case. I guess if I could determine the y value
on the plane at a given x and z, I could use that, but I don't
know how to do that given the 3 vertices that I have. Or maybe
I'm thinking about this completely wrong.  share|improve this
question add comment  2 Answers  up vote 1 down vote accepted
My first thought