Curve Editors
(The Making of a Bouncing Ball)
In this tutorial we are going to be creating a bouncing ball animation using the curve editor for the majority of the animation.
The curve editor is a separate window in 3DS Max that shows your animation as function curves. These curves can tell us all about how our objects are moving in our scenes and gives us some extra control over how the animation moves between keyframes.
First thing as always is to open a new scene in 3DS Max. Once you have that, you can create a sphere to represent your bouncing ball.
Go to the create tab and in the Geometry standard primitives click on sphere. Then in your top viewport drag out a sphere of your liking. I made mine and then in the Modify tab gave it a radius of 15.
The size of the sphere really doesn't matter.
It is the animation we are concerned with but if you want to keep things the same as the
scene I am creating for this tutorial so as not to get confused, then I suggest matching my
parameters.
In the future, you should realize though, that using the curve editor in the same manner will
produce a very similar animation, just a different size than the one we are creating here.
Next, We are going to our Left Viewport, and raise the ball to a height that we want our ball to start falling. This will give us a starting point and a reference point for our curve later.
I have raised my sphere to a height of 150 along the Z axis. I got it to be this exact by using the XYZ coordinates at the bottom of your 3DS Max screen below the timeline.
My sphere was created at 0.0 for
all 3 X,Y,Z coordinates.
Then all I had to do was type in 150
and hit enter to move my sphere
along the Z axis (up and down)
This is a nice way of getting exact heights and measurements should you ever need to be exact. I have found that It will help us visualize the bouncing ball in our animation curves later to be as exact as possible.
Once your ball has been raised in the front viewport like above. Then we are ready to open up the curve editor and begin our animation.
There are two versions of the curve editor. The Mini Curve editor and the Curve Editor. The mini curve editor is down below your timeline at the far left of your screen. It is the white icon that looks like this.
The regular curve editor has a few more buttons and features, but for our purposes the mini curve editor will do just fine. If you need to find the regular Curve Editor. Go up to your main menus and click on Graph Editors --> Track View - Curve Editor.
Back to work! Click on the button to open up the mini curve editor as shown in the last image above.
Your timeline changes to the above looking graph editor. The double yellow lines is your timeline scrubber now, and the frames are shown along the bottom. at the right of the scrubber/frames you have a column of numbers from zero on up (and down). These are the coordinates along whichever axis you are traveling. If you are editing the curve for the Z axis, these are the coordinates for the Z axis.
See now why I said being a little more exact would help us in the curve editor?
To the right of the coordinates, you will find a large list of pretty much everything that can be found, or is found in your scene.
You can click and drag this list up or down to show all the items and things it contains. Find the one that Says "Objects" with a little cube icon next to it.
The objects section will contain all of your 3D Models, Primitives, etc. in your scene. In our case we have only made a sphere thus far. So Sphere01 appears under Objects, along with all of Sphere01's Transforms such as Position, Rotation, and Scale for every X,Y,Z axis.
The part we are worried about for this demo is the Position area, as highlighted above in red. We will start with the Z axis, as that is the axis that goes up and down (kind of like a bouncing ball). click on the Z Position and then look to the right at the graph.
The graph to the right should changed now that you have made a selection in the list to the left. You will see a dotted blue line, straight across the graph starting, at the 150 mark on the graph (remember putting your sphere in the 150 Z position earlier).
This dotted line will be our curve. The reason it is not a curve yet, is because we have not given it any keyframes, or instructions.
Here is a good place to note that in the graph area of the curve editor, you can use your middle mouse button to scroll back and forth and zoom in and out of the graph. You can click and drag with your middle mouse button anywhere inside the graph and drag it to the left right, up and down to pan through your graph editor as well.
The above image of the graph is zoomed in rather far and only shows us the Z axis position from 110 to 150. We want to be able to see it from 0 to 150. Zero will be our ground level. where the ball hits and then starts traveling back up.
Zoom the graph out now and position it to get the full picture for our animation. Kind of like this:
Now we are able to see the position side of the graph from 0 up past 150 where our blue line starts, as well as the 0 point.
We can also see our frames along the bottom from 0 (start of animation) to 100 (end of our current animation.)
Now we are ready to start building our Z axis position curve.
Your buttons are along the top of the graph editor.
Filter | Move, Slide | Scale, Scale | Add | Draw, Reduce
| Keys Keys | Keys Values | Keys | Curves Keys
Fairly similar to your normal functions in one easy to use icon menu.
^
|
The first one we are going to use is the Add Keys button. The one above with the + sign over a curvy line and a square.
Once the Add Keys button is pressed, click along the dotted blue line, starting at frame zero, and moving down towards 100.
Make 8 keyframes in total, like below. It doesn't matter right now where they end up, we will change that in the settings next.
The grey squares will show up along the line (these are your keyframes, and your dotted blue line will turn solid in between keyframes.
When you are finished creating keyframes, click on the Move Keys button, in order to turn off the Add Keys (this safe guards against accidentally adding more keyframes.)
Now go to frame zero in your graph, find the first keyframe and right click on it. A settings dialogue box will pop up.
If you have done this in order and taken a look at the Tangents tutorial, you will recognize these settings! In the top left corner is our keyframe number and the jump to keyframe buttons back or forward.
Below that is the Time (our 1st keyframe, was placed at 0 on the timeline.) If yours does not say zero, then simply change it to a 0 by typing it in and hitting enter here, or
using the slider arrows on the side.
Below the Time, is our Value setting (recognize that 150 again) this is where our object is at based on the coordinates along the Z axis.
And finally, we have our in and Out tangents. We will be using these to make our ball bounce more realistically.
Now that we are in the settings you can adjust your Time, Value, and Tangents to match the ones in the image above.
For our very 1st of 8 keyframes:
Time should be 0 - (this is your animation timeline frame)
Value should be 150 - (This is where your sphere is along the Z axis)
In and Out: Tangent should both be Slow, (check the curve in the image above and match it. This will make our ball start falling slowly, and then speed up as it gets farther away from our first keyframe.)
When you are finished, simply click the arrow pointing to the right in the upper left corner next to your Keyframe number. (Don't click the one next to the out tangent)
This will automatically take you to the next keyframe #2.
Notice the changes... the number in the upper right has changed to a 2. This is because we have moved from our first keyframe that we created along our blue line, to our second one.
The Time: setting, wherever you clicked to create a keyframe, you can now change to whatever keyframe you would like it to land on. Change this to 20, and hit enter. This means that our next keyframe will happen at frame #20 on our timeline.
The Value: setting, this will say 150 for you, because we have not adjusted our curve yet. Change it now to 0.0 and hit enter.
This changes the sphere's position along the z axis. Moving it from 150, to 0 which is our "ground level". In other words, our ball falls from top (150) to bottom (0).
The In: and Out: Tangents, These ones should be set to the Fast tangent. Check the image above and match the curve symbols to your choice. This means that the object (our ball) will speed up as it gets closer to our second keyframe, and it will also start fast as it leaves our second keyframe.
Think about a ball falling from a height. It starts slow and gains speed as it falls, it hits the ground at its fastest rate of speed, and leaves the ground to bounce back up into the air at its fastest speed, slowing as it gets to its highest point before falling again.
Once you have made the changes to the first two keyframes, take a look at your curve in the curve editor. It should look like this:
Does it happen to look like the path a falling ball might take from its highest height in the air, down to the ground and then back up again? Perhaps there is reason behind this curve editing stuff after all!
When you are finished looking at your curve, go back to the keyframe settings and hit the right arrow next to the keyframe number again to get to the 3rd keyframe settings.
Your keyframe number in the upper right should now say 3. We have moved on to our third keyframe.
Change the settings now whatever they may be, to the ones in the image above, or follow the directions below for more descriptive reasoning.
Time: setting should be changed from whatever it was when you clicked along the line, to frame 35 now. We want our ball to steadily decline in height for this demonstration. So, our last keyframe had 0-20 ... 20 frames in between the keyframes. This time 20-35 will only have 15 in between.
Value: This should be set to 100.0 for our demonstration. It will not reach its original height of 150 along the up and down axis (Z axis). It gets lower as it loses power, and momentum, and with less distance to travel it speeds up a little. Gravity in the real world tends to force this trick as well, based on of course what your ball is made of. It will take gravity longer to work on a super bounce ball, than a basket ball. Some balls are just more springy than other balls.
The In: and Out: Tangents - These should again be changed to match our first keyframe, using the Slow tangents. As our ball reaches its new height of 100 it slows down, and then slowly leaves the 3rd keyframe on its decent towards ground level again.
When finished adjusting your settings accordingly, click the right arrow next to 3 in the upper right corner of the settings window, to travel onwards to keyframe #4's settings.
The 4 in the upper right tells us we have arrived at our destination.
This is once again as the ball falls to ground level. So we reduce the space between keyframes again to speed it up a bit, and make its Value: setting at zero to bring our ball to the ground level by frame 45 of our animation. Tangents again change to fast, like above.
When finished with the frame four settings, click the right arrow at the top left again and head to frame 5.
We arrive at frame #5 as shown in the upper left corner of the window.
The time gets slightly reduced again to speed up our ball as it travels less and less high.
Time: 53 - We only move 8 keyframes forward now.
Value: 50.0 - We reach a height of only 50 this time, cutting down yet again as the ball loses power and gravity does its job.
In: and Out: Tangents: are set again to slow, back and forth as the ball speeds up at the ground and slows down in the air.
When finished move on to frame #6 in the same way as before.
Back at ground level our ball has once again traveled to the earth as its bounces get lower and lower.
Time: We have only moved forward 5 frames now to 58
Value: Is 0.0, back to the ground level.
In: and Out: Tangents: again at ground level, they turn to Fast so our ball can once again gain some power and move upwards.
When finished adjusting your settings to match the above, then click the right arrow in the upper left corner of the settings again to move on to frame #7.
At keyframe #7, our ball is getting nearer to the ground still and the speed is even leveling out now as it starts to slow down itself.
Time: 63, we travel 5 more frames forward as things start to level out all together.
Value: 20, our ball is near the ground now and doesn't gain much height during this bounce at all.
In: and Out: Tangents: We are up in the air again, even if it is lower to the ground. So our tangents change to slow.
When finished adjusting your settings to match the above, move to the last keyframe ... #8.
Our ball falls to the ground for the last time here. It will not rise again as it is tired of fighting gravity and is ready to rest.
At Keyframe #8 we change our settings for the Z axis for the last time.
Time: 68 - we travel 5 more frames evening out our last bounces final decent to the ground level.
Value: 0.0 - Our ball hits the ground for the last time here and stays on ground level.
In: and Out: Tangents: Our tangents are set to Fast so the ball still speeds up as it nears the ground and gravity works it's magic.
When you are done adjusting your last keyframes settings, then close the keyframe settings window by clicking the X in the upper right hand corner of the window.
Now that all of our keyframes have settings, look at the blue line in our Curve Editor.
Do you see a pattern here?
The line actually looks like the path a bouncing ball would take as it loses momentum and returns to the ground.
Now click the close button in the mini curve editor and look at the front viewport and play your animation.
The ball goes straight up and down, but it does look like it is bouncing and returning to the ground doesn't it?
It only travels in a straight line because so far, we have only adjusted settings in the Z axis. Up and Down only.
With a similar curve laid over our ball at its keyframe, we can really see the correlation.
Our next task, is to make this bouncing ball move along the X axis so that it really looks like the ball is traveling somewhere.
Head back down and open up your mini curve editor again.
Where we have Z Position highlighted in the list to the left of our curve, right click on Z Position to bring up the right click menu.
The right click menu appears, and in the top left corner you will find the word "Lock". Click it.
The right click menu disappears and we see our graph and list again. The Z Position says (Locked) next to it. This means we will be able to see our Z axis curve still, but we won't be able to change it until we unlock it again. This helps us when you start working with multiple curves, so we don't accidentally mess up all of our hard work!
Now, in the menu to the left, hold down control while Z Position is still highlighted and click where it says "X Position".
With both X Position and Z Position highlighted in the list, we will be able to see both the red and blue curves for Z and X axis, but we will only be able to change keyframes in the X axis.