You keep asking if this requires one pass or two. The way the OP is doing it requires two passes, but I can think of a way to do it in one pass, using mirrors. But that has nothing to do with the question of stereo projection.

Meanwhile,

You're still not understanding it. He does not mean 6 inches to the right IN THE WORLD. He means six inches to the right of its position in the first pass. Look at this illustration. The left-eye camera has a red arrow. The right-eye camera has a green arrow, and stays six inches to the right of the left-eye camera, with respect to the orientation and position of that camera, not the world.

Imagine these are key frames.

In the first key frame, the right-eye camera is +6 in X. In the last key frame, it is -6 in X. In the middle key frame, the translation in X is almost zero, and the translation in Z is almost 6 inches. You cannot manually set up these positions as an adjusted key frame. You must do this via parenting. Any attempt to do it manually will result in eye-angle and distance deviations that will be obvious when viewed on a 3D TV. You will make people throw up.

We don't need to see the key frames of his actual scene. This has nothing to do with adjusting his animation. It's the simulation of stereo vision, using two cameras or one camera rendered twice, with a shift in position. Or one camera with a split mirror setup.

 

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)