How to draw a Perspective-Correct Grid in 2D

Question

I have an application that defines a real world rectangle on top of an image/photograph, of course in 2D it may not be a rectangle because you are looking at it from an angl

Answer 1

What you need to do is represent it in 3D (world) and then project it down to 2D (screen).

This will require you to use a 4D transformation matrix which does the projection on a 4D homogeneous down to a 3D homogeneous vector, which you can then convert down to a 2D screen space vector.

I couldn't find it in Google either, but a good computer graphics books will have the details.

Keywords are projection matrix, projection transformation, affine transformation, homogeneous vector, world space, screen space, perspective transformation, 3D transformation

And by the way, this usually takes a few lectures to explain all of that. So good luck.