I have rendered this no loop GIF using Blender Render.
I want to:
1) Make the envelope invisible at the first frame.
2) Make it fade in so that it's transparency is at zero when it reaches the center.
3) Make it fade out when is goes back up.
Lets consider. I have placed a Plane1 in front of all objects, and I want to animate the plane to be...
1) Opaque to translucent. (say 0-20 frames)
2) Translucent to transparent. (say 20-40 frames)
3) Transparent to translucent. (say 100-120 frames)
4) Translucent to opaque. (say 120-140 frames)