Fiddled with the math and cleaned it up a bit. Should be more correct now. Handles the screen aspect ratio, removed jquery dependency, and fixed the fov to use correct values.
dropbox.com/s/lm18u6bxn49note/mode7js3.capx
I probably should remove the previous examples.
MasterQuest
This capx does the positioning math with the projectionpoint function. If you're asking about the original effect then the math would be similar but not the same. I won't be finding the math for the original effect because I found it broken. I made this instead.
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You can see if the update works better for you. I'm not sure if how it was before was causing the issue. I don't have a lot of time to debug what's amiss in other projects currently.