Windows 7 Professional 64-bit w Service Pack 1
Display Card: Nvidia GeForce GTX 760
Blender 2.69 - r60995
There is a bug in the subdivision of animation curves.
See the attached file: “curve bug.blend”
The three cubes are animated from -5 units on Y to +5 units on Y over the length of the animation.
The green cube has had one extra keyframe added. This was done by simply going to time frame 125 and using the I key to add an extra location keyframe. No translations were made to the green cube prior to adding the extra keyframe. It can be seen in the animation that the simple addition of this extra keyframe has altered the speed of cube relative to the other two cubes that do not have the added keyframe.
It will be seen that the handles of the added keyframe do not respect the slope of the existing animation curve. This is not correct behaviour. Since there has been no change at all to the cube, the desired end result would be a subdivision of the animation curve and handles as required that still retains the existing slope.
The attached file, “incorrect curve.jpg”, shows the incorrectly altered animation curve (in green) relative to the form of the animation curve as it existed before the addition on the extra keyframe (in yellow).
By way of comparison, the subdivision of curves in the edit mode is handled correctly. Here it is obvious that the curve is retaining its form and slope no matter how it is subdivided. See attached file, “edit curve subdivide.jpg”