And starring the SUN and the EARTH and the MOON!
If you have any STATIC channels be sure to Edit menu > Delete by Type > Static Channels. It depends on how you set the Keyframes!
What has been achieved at this point? You have all three objects sized and in the proper position and animated to rotate 360 or 720 degrees around thier own axis (pivot point).
a. Create a GROUP consisting of just the EARTH. Edit menu > Group command with only the Earth selected. What is the keyboard shortcut for the Edit > Group command? b. Name the GROUP earthOrbit or EarthOrbit. c. The Pivot Point for any newly created group is at the center of the entire 3D grid, i.e. at (0, 0, 0). How convenient! That is exactly where the SUN is centered. We do NOT need to change the PIVOT POINT for the earthOrbit! d. Be sure to switch from Object mode selection to Hierarchy mode selection, if needed. H O C (HOC is the KEY). Note: You can always use the OUTLINER to select objects or to select the GROUP or entire hierarchy too. That would be SLOWER here and not needed. e. Make sure the Time Slider is set to Frame #1, the beginning of the animation. Make sure that the Earth Orbit is the selected object. (Not the EARTH, but the EarthOrbit, which is a Hierarchy, i.e. the H in HOC). f. Press s to set the keyframe. g. Move to the last frame, probably Frame #48. i. Change the RotateY for the EarthOrbit to 360 or 720. j. Press s to Set the Keyframes. k. Now remove the Static Channels to clean it up and only leave RotateY keyframed for the EarthOrbit.
a. Create a GROUP consisting of just the MOON. Name it MoonOrbit. b. Make sure Snap to Grid is turned on. c. With the MoonOrbit selected (and NOT just the Moon object), and with the Move Tool active, press the Insert key. Drag the RED manipulator of the MoonOrbit Pivot Point until it Snaps to the GRID point on the X axis where the Earth is centered. Now press the Insert key again to get out of adjust pivot point mode. d. With selection mode in Hierarchy mode (the H in H O C), click on the Moon and because you are in H Hierarchy mode instead of O Object mode, what happens? The MoonOrbit is selected. e. Hold down the SHIFT key and click the Earth. You are still in H mode instead of the O mode of HOC, so the EarthOrbit is added to the selection, and is the 2nd item selected. Recall: Click the item you want to be a CHILD first, i.e. tap the child on the shoulder first. Then, hold down SHIFT key and click the 2nd item, which is who you want to be the PARENT of the CHILD. Shift-CLICK the parent on the shoulder 2nd. f. Edit menu > Parent command established the relationship of the EarthOrbit being the parent of the MoonOrbit.
a. Did you have the EarthOrbit selected? b. Click on the RotateY attribute name in the Graph Editor window. c. Type the F shortcut to Frame the selected attribute's GRAPH and notice how it is curved as it comes out of the start keyframe and it is curved as it arrives at the 2nd keyframe. d. Draw a bounding box around the keyframe at Frame #1. Do the Tangents menu > Linear command. e. Repeat for the keyframe at Frame #48 (or whatever frame you have for the end of your animation.
Do this again after a break or do it again tomorrow. Does it go faster each time? Do the concepts and techniques make more sense with repetition?