How to get a intersection btween a line and a face

[Mcdull]

there are many triangls in the bottom,but they are not in one plane, i generate a line with two points,and the line is vertical to the XYplane ,i want to get the intersection btween the line and a face.
i read the api that

 # This is really the normal which follows the x axis. The plane is
 # perpendicular
 plane1 = [Geom;;Point3d.new(-10, 0 ,0), Geom;;Vector3d.new(1,0,0)]

 # This line follows the x axis
 line1 = [Geom;;Point3d.new(-10,0,0), Geom;;Vector3d.new(1,0,0)]

 # returns -10, 0, 0
 pt = Geom.intersect_line_plane(line1, plane1)

but this method turn every face to be a plane，so，the intersection may be outside of the face,i want to get the intersection in the face...
would u give me some help？thank u

[TIG]

You need to get the line of the edge and the plane of the face
line=edge.line plane=face.plane
Then use line/plane intersection tests etc...
http://code.google.com/apis/sketchup/docs/ourdoc/geom.html#intersect_line_plane

[Mcdull]

ok, i got it,but there are many intersection points .the line have intersect with every face's plane,if i wanto to get the intersection point in the face,not the other faces' planes,do i have to judge with the method Face.classify_point
or other methods?
thank u ,TIG

[TIG]

You could also look at model.raytest
The point could be one that you used for your vertical edge and the vector is [0,0,-1]
It will return any array raytest[0] is the intersection point and raytest[1][-1] is the face or edge it hits...
http://code.google.com/apis/sketchup/docs/ourdoc/model.html#raytest