Hello! I would just like to know how to do absolute keyframing (?) with meshes. I would like to use this for masks in compositing.
I mean it like this:
I am on frame 1. I enter edit mode and grab one of the vertices on the cube. I drag it in some weird direction. I then make a keyframe for the cube’s shape. I do the same thing on frame 2. So on and so forth. When I insert mesh keyframes, the mesh does not animate. It just creates a new shape key.
Please help! - YA
ya, I just did a whole bunch of this kind of thing…
What you are looking for is shape keys. They are located on the other tab with the modifiers in 2.49.
To use them just add one shape key without moving anything.
That is you basis, so don’t touch it again just create it then tab in and out of edit mode so it sticks.
Then create another on while in object mode.
Then go into edit mode and move vertices around, and go back to object mode.
When you are in object mode you will see a slider in the shape keys box if you move it, you will see your mesh move.
So to make this easier just divide a window so that you have an actions window and hit zero so that you are looking through the camera. Make sure that the video is in the background and that your camera frame and lens are set up properly or your going to pay for it by having to redo everything later.
Go ahead and create a shape key. Normally I will put the frame number into the shape key name box so that they are easier to find and adjust later.
So then go for it. move your timeline forward until the shape of the thing you are masking is at an apex. That is the shape has moved all the way in one direction and is about to move in another. At that point add a shape key. If you have an actions window open you can go to the view menu in it and click “show sliders” Then you want to have three keys for each position. The last one off. The current one on. The next one off. If you forget to turn off the keys in each new position you mesh will look all screwy so don’t forget that.
If you need help setting up nodes for blending your matte let me know… 
Thanks! This will work great! I would love to see your nodes! I was doing it without nodes, but seeing yours, I would assume, would make what I am doing better.
Ok, so what I did is pretty simple. Someone else would probably have a better way but I couldn’t find a tutorial that worked for me, so I just made it up on my own.
The masks are just materials set to full green (no other color) set to not accept light or shadow. Then I used a set alpha from the mask output of the chroma key and then added some blur and used that for the factor on the alpha over. That helps clean up the rough edges that show through.
