Animation, Part 1. Your First Animation
(version September 16, 2007)
These are short articles covering technical ap sects of 3D. They are chosen because they are collections of key topics useful to the beginner in learning 3D animation, rendering and modeling. This article is intended to get you up to speed using trueSpace 7.51 for animation. We'll work with a nitrogen and a hydrogen atom, and animate both of them. The steps are described below. You should read over the article first, then try to follow along on your own in the 3D Animation Lab. By working through the steps you will have down the basics of animation and will be ready to move on to more challenging projects.
The opening screen. Down below you see the Workspace screen for trueSpace 7.51. We have loaded a nitrogen and a hydrogen atom, positioned them as show, and scaled them down a bit so that we have plenty of room in which to play. We will set up an animation for both atoms, have the atoms collide, and then have the atoms move away from each other. That's our story here. First, let's take a closer look at our screen and point out some information to you.
Take a closer look at the lower left corner of the screen. The Hydrogen atom is selected (Green) and we are at frame zero, shown below the text "Hydrogen,1" as "0.00". This is the starting point for the animation.
The lower right corner of our staring screen (the lower middle) shows that our default last frame is number 300. We will leave this control as it is. But, if you wanted to change the ending frame here, just click into the number "300" and type whatever value you want. We are using frame numbers here. There are other methods for tracking the animation, but we'll just the default here as 300 frames. Typically animations play at the rate of 30 frames per second, so will have 10 seconds of animation for 30 frames each second, or 300 frames. Once you have these basic ideas under your belt, you will make other choices as you need. We recommend following with these same values for now.
Go back to the image right above of the lower left of the Workplace screen. The red line is our timeline. We will use that line to adjust what frame we are at. I have other choices as well. Notice where the text "0.00" appears. I can click in here and change the frame number by typing it in. Feel free to use any method you like.
Here are some important rules on how to proceed. If you follow these rules in the beginning, your animations will come out as you intended.
(1) Move the red frame slide the the frame you want.
(2) Adjust the position of the atoms as you wish: change position, size or rotation.
(3) Click on the "RED BUTTON" showing the image above on the VCR-style controls. That is the "RECORD FRAME" button.
Key Frames
We will be using a idea called "KEY FRAMES", which is an important basic concept in animation. We'll take a few moments here to explain it in some detail. If this is your first animation, you will quite possibly look over some detail and make some incorrect judgments. Overtime you will learn how to think in terms of "KEY FRAMES". This will take your further along in learning the Vocabulary of 3D, a group of concepts that will help you work naturally when using 3D software. Right now KEY FRAMES and FRAME SLIDER are not part of your normal vocabulary. It will take some time for the terms to become part of the complex vocabulary of 3D that you will use well.
What exactly is a key frame? The basic idea is that you are informing the software to associate the object's current position, size and rotation with the frame number. That part of the story. For key frame 0 above we will press the red record button and the system will remember where the atoms are, what their rotational position is, and what their size is.
Let's move the frame slider to frame 60. We'll adjust the atoms, and then press the RED RECORD BUTTON to record key frame 60. Now we'll talk a little bit more about the meaning of key frames. Key Frames only know the position, rotation and size that is associated with their frame number. If you moved the atoms all around in different locations with different rotations and different sizes between key frame 0 and key frame 60 and there are no key frames in between, then all that moving is unknown to key frame 0 and key frame 60. They only know about where things were at the time the RED RECORD BUTTON was pressed.
By using first the rewind button and then the play button, by animation will play through. I will see the atoms move from where they were at in KEY FRAME 0 to where they are now in KEY FRAME 60. Anything that happened between KEY FRAME 0 and KEY FRAME 60 was not seen, so any wiggles or squiggles I made with the atoms are not seen. [Footnote just to be complete: We are assuming here a linear interpolation between key frames. Other interpolations may perform differently. More on this in a future topic.]
To complete setup here, we'll make one more change. Click in the Animation View then click the Settings tab (top right of screen), which will bring up the Animation Preferences. You will see the following controls; uncheck REPEAT (click on it) so that your animation does not continuously loop when you play it back. This feature is often handy to turn on, but we will find it easier to start with REPEAT turned off. Notice that this panel is where you can change frame rate and Time Format for the animation. Check out some of the pulldown, but after doing so leave everything as it is here.
Shown below is the very bottom of the trueSpace 7.51 display. Note the gen "notch" in the middle at the top of the Animation View (circled in red below). This is a slider which can be dragged to increase the size of the viewing area in the Animation view. Try adjusting it up and down to view its effect.
We'll first expand the Animation View area to show more of the details.
Nitrogen on the left, Hydrogen on the right.
Steps in creating our animation of the two atoms:
1. The Hydrogen atom (green) is selected. The key frame counter is at 0. Click the RED RECORD button to record a key frame for Hydrogen.
2. Click the Nitrogen atom (blue) to select it. The key frame counter is at 0. Click the RED RECORD button to record a key frame for Nitrogen.
3. Click the Hydrogen atom (green) again. Slide the red key frame slider to frame 60 by dragging it to this frame. You click in track right above the green divider across from the text "Hydrogen, 1". Move the Hydrogen atom half way to the Nitrogen atom and rotate the electron by rotating the green sphere. Click the RED RECORD button to record a key frame for Hydrogen.
4. Click the Nitrogen atom (blue) to select it. Move it until it is in contact with the Hydrogen atom (green). Rotate the Nitrogen atom (blue) to change the position of the electrons. Click the RED RECORD button to record a key frame for Nitrogen.
The scene now looks like this:
We'll get back to step 5 in building the animation in just a minute. First a few comments about what we have.
You can use the VCR-controls to rewind the animation and play it now. If you do so, you will see the atoms rotating and moving closer and touching. The movement will be smooth and spaced evenly over the 60 frames When you are playing back the red key frame line will continue moving past 60 to frame 300, but the atoms will be standing still at the point. The 3D software has generated all the in between from 1, 2, 3, ...,10,...,20,...,30,...,40,...50,...,59. You only had to set up frames 0 and 60 to get this effect. This helps explain what a key frame is. You set up a key frame in order to have the 3D software interpolate how the atoms need to get to the current key frame from the previous one. We could do a variety of edits at this point, but let's continue instead with building more of the animation.
5. The two atoms have "collided". We will now have them bounce back from each other and move off the screen. Select the green Hydrogen atom. Move the red key frame slider to Frame 120. We will have the green Hydrogen atom move to the top right of the screen and go off it. Adjust the green Hydrogen so that it travels have this distance and rotates. Click the RED RECORD button to record a key frame for Hydrogen.
6. Select the blue Nitrogen atom and have it move toward the lower right about half the distance. Rotate the Nitrogen atom. Click the RED RECORD button to record a key frame for Nitrogen.
The scene now appears as shown below. Test your animation: rewind the animation and then press play.
We are close to finishing up. Let's make a key frame at 240 then at 300.
7. Move the red key frame slider to Frame 240. Adjust the green Hydrogen so that it is nearly off the screen at the top right. Rotate the green Hydrogen atom. Click the RED RECORD button to record a key frame for Hydrogen.
8. Select the blue Nitrogen atom and have it move further toward the lower right until it is almost off the screen. Rotate the Nitrogen atom. Click the RED RECORD button to record a key frame for Nitrogen.
The results of steps 7 and 8 are shown below.
7. Move the red key frame slider to Frame 300. Move the Hydrogen atom at the top right until it is off the screen. Click the RED RECORD button to record a key frame for Hydrogen.
8. Select the blue Nitrogen atom and have it move off the screen at the lower right.. Click the RED RECORD button to record a key frame for Nitrogen.
Test the results by clicking Rewind and then Play the animation.
We are essentially done except for rendering to an AVI file. Check out the results by double-clicking on the image below:
Additional articles and tutorials about animation will follow.
Additional articles will appear in this section.
Topics for further exploration and reading on your own
1. Add a third atom (Carbon) of a different kind. Change the animation to include the third atom.
2. In the Animation View click on FCurve, then click on the arrow in front of the Matrix selection for each atom. What do you see? Can you understand these curves in terms of what the atoms are doing at each key frame.
3. Put the cursor over any curve that you see and right click to get a popup menu. Take a look at the Interpolation choices. Try each one of these out and observe how the curve changes. Play back the animation with the changes in the function curves.
4. To get the most out of your work go back to the manual and read about the function curves in the chapter on Animation (Chapter 9).
We enjoy hearing from you. Some of the questions listed above will appear in future "Topics in 3D" articles. Please send your comments about this article to 
