Changing the timing of an attribute
The ball seems to move too slowly in its journey. In the following steps, you'll use the Graph Editor to
hasten its movement. Specifically, you'll cause the ball's animation to finish its journey in two seconds (48
frames) rather than three (72 frames).
To speed up the animation of the ball's movement
1. Drag a selection box around all key points of both curves.
2. Select the Scale tool.
3. Click and hold the middle mouse button anywhere in the graph at frame 1 (slightly to the right of
0).
Notice the question mark icon. The location of this icon indicates the point from which scaling
occurs. (Because you need to scale the animation inward toward frame 1, you need to start your
drag operation at frame 1.)
4. Without releasing the mouse button, drag to the left until the right-most key points on both
curves are positioned roughly at frame 48. (When selected, the right-most key points are yellow.)
This scales the curves symmetrically towards frame 1. The animation of the ball now plays from
frame 1 to 48 rather than 1 to 72. The ball traverses the scene in less time, which, of course,
means it moves faster.
If you had started your drag operation from the middle of the frame range, the scale operation
would have pulled the curves toward the middle of the frame range. You can snap the keypoints
to whole values to keep the keyframes on a consistent timing.
5. Widen the Graph Editor window as necessary to see the graph clearly. Also, dolly the view or
select View > Frame Selection (in the Graph Editor window).
Fine tuning an animation
Now you can improvise adjustments to the animation on your own. For example, you might choose to
speed the ball's horizontal movement up to the first bounce but not thereafter. You might also decide to
raise the peak height of the ball's motion so that it doesn't seem to hover over the fence unrealistically.
Whatever you choose to do, you'll likely need to edit both the Translate X and Translate Y curves, not
just one of them. Play the animation after each adjustment.
The following two figures show examples of curves after modification.The two graphs are identical,
except the curve points are selected in the second figure. The second graph shows the position of the
tangent handles.
If you want your curves to match the shape of the curves in the above figure, here's what you would
need to do:
To adjust the animation curves to match the above images
1. On the Translate X curve, delete the three key points between the two key points at the end.
(The preceding figures show the curve after the points were deleted.) To delete the points, drag
a selection box around them and press Delete.
With fewer key points on the curve, it's easier to maintain the curve's smoothness for larger
distances as you edit its shape. Small kinks in an animation curve can ruin an otherwise perfect
animation, so it's useful to remove key points that you aren't using.
2. On the Translate X curve, select the left-most key point and move its right tangent handle down
slightly. (Remember to use the middle mouse button when moving a handle or point.) Select the
right-most key point and move its left tangent handle up slightly.
Notice that the slope of the Translate X curve increases slightly in the early part of the animation,
then tapers off toward the end. This causes the ball to accelerate slightly at the beginning of the
animation, then decelerate after its first bounce.
3. On the Translate Y curve, remove the key point at frame 22. (The preceding figures show the
curve after the point was removed.) This point wasn't essential to the curve shape.
4. On the Translate Y curve, select the left-most key point and move its right tangent handle up
slightly.
5. At the key point where the bounce occurs on the Translate Y curve, move the left tangent handle
up a bit. This raises the high part of the curve left of that key point, which makes the ball rise
higher over the fence.
6. If you want to change the shape of Translate Y curve but lack adequate control with the existing
key points, you can add a key point at the position of your choice. (No key points were added in
the prior figures.) To add a key, click the Add Keys Tool icon, select the curve, and middle-click
the desired position on or off the curve .
The ball seems to move too slowly in its journey. In the following steps, you'll use the Graph Editor to
hasten its movement. Specifically, you'll cause the ball's animation to finish its journey in two seconds (48
frames) rather than three (72 frames).
To speed up the animation of the ball's movement
1. Drag a selection box around all key points of both curves.
2. Select the Scale tool.
3. Click and hold the middle mouse button anywhere in the graph at frame 1 (slightly to the right of
0).
Notice the question mark icon. The location of this icon indicates the point from which scaling
occurs. (Because you need to scale the animation inward toward frame 1, you need to start your
drag operation at frame 1.)
4. Without releasing the mouse button, drag to the left until the right-most key points on both
curves are positioned roughly at frame 48. (When selected, the right-most key points are yellow.)
This scales the curves symmetrically towards frame 1. The animation of the ball now plays from
frame 1 to 48 rather than 1 to 72. The ball traverses the scene in less time, which, of course,
means it moves faster.
If you had started your drag operation from the middle of the frame range, the scale operation
would have pulled the curves toward the middle of the frame range. You can snap the keypoints
to whole values to keep the keyframes on a consistent timing.
5. Widen the Graph Editor window as necessary to see the graph clearly. Also, dolly the view or
select View > Frame Selection (in the Graph Editor window).
Fine tuning an animation
Now you can improvise adjustments to the animation on your own. For example, you might choose to
speed the ball's horizontal movement up to the first bounce but not thereafter. You might also decide to
raise the peak height of the ball's motion so that it doesn't seem to hover over the fence unrealistically.
Whatever you choose to do, you'll likely need to edit both the Translate X and Translate Y curves, not
just one of them. Play the animation after each adjustment.
The following two figures show examples of curves after modification.The two graphs are identical,
except the curve points are selected in the second figure. The second graph shows the position of the
tangent handles.
If you want your curves to match the shape of the curves in the above figure, here's what you would
need to do:
To adjust the animation curves to match the above images
1. On the Translate X curve, delete the three key points between the two key points at the end.
(The preceding figures show the curve after the points were deleted.) To delete the points, drag
a selection box around them and press Delete.
With fewer key points on the curve, it's easier to maintain the curve's smoothness for larger
distances as you edit its shape. Small kinks in an animation curve can ruin an otherwise perfect
animation, so it's useful to remove key points that you aren't using.
2. On the Translate X curve, select the left-most key point and move its right tangent handle down
slightly. (Remember to use the middle mouse button when moving a handle or point.) Select the
right-most key point and move its left tangent handle up slightly.
Notice that the slope of the Translate X curve increases slightly in the early part of the animation,
then tapers off toward the end. This causes the ball to accelerate slightly at the beginning of the
animation, then decelerate after its first bounce.
3. On the Translate Y curve, remove the key point at frame 22. (The preceding figures show the
curve after the point was removed.) This point wasn't essential to the curve shape.
4. On the Translate Y curve, select the left-most key point and move its right tangent handle up
slightly.
5. At the key point where the bounce occurs on the Translate Y curve, move the left tangent handle
up a bit. This raises the high part of the curve left of that key point, which makes the ball rise
higher over the fence.
6. If you want to change the shape of Translate Y curve but lack adequate control with the existing
key points, you can add a key point at the position of your choice. (No key points were added in
the prior figures.) To add a key, click the Add Keys Tool icon, select the curve, and middle-click
the desired position on or off the curve .
No comments:
Post a Comment