# Transforming points on a coordinate plane to their perspective equivalent?

I am currently working on a computer program that can properly plot a point on a 2d coordinate plane that has had its perspective changed to be tilted backwards. I don't have any information on how much the plane has been tilted. I can only get the four points of the resulting 2d trapezoid that makes up the tilted plane. Given a point that exists on the tilted plane, how can I translate it properly to the point that it should appear on the viewport? And given the four points of the trapezoid, can I calculate any tilt or rotation of the perspective plane in relation to the viewport?

My coordinate geometry terminology is a little fuzzy, so apologies in advance if my explanation is a bit unclear.

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This is pretty close to a duplicate of 2D transformation. See if my answer there helps. – robjohn Sep 26 '11 at 17:20
Thanks, this looks to be exactly what I'm going for. Now to just digest the info from the Wikipedia article so I can turn it into code. – Mike C Sep 26 '11 at 17:29