Path Constraints in 3ds Max - Time & Speed
In this tutorial, learn how to control the timing and speed of a constrained object. In this example, the object you are constraining is a car. Through this tutorial, you will learn how to constrain the path to its predefined path so it adheres to basic traffic rules.
- Recorded in: 3ds Max 2010
- This tutorial is intended for use with 3ds Max version 2010 or higher.
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When you constrain an object to a path, the object is moved with its
pivot point aligned to the starting point of the spline.
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You can then move the path in the scene to prevent any problems
such as a car sunk underground.
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Once an object is constrained to a path, it moves along that path
at a constant speed. This is the default setup.
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Sometimes you need to control timing, in this case to have the car
respect red lights and avoid jaywalkers.
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An easy way to achieve this is to start by deleting the two keyframes
that the Path Constraint tool created.
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These two keyframes represent percentage of travel along the path,
from 0 to 100.
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From that point on, turn on Auto Key mode. Scrub along the timeline
to a point right after the light turns red.
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As you move the car to the intersection, notice that the car only
moves along the path.
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All other directions are restricted.
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To make the car pause at the red light, copy the last key to a point
right after the light turns green.
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A copy is made by pressing the Shift key and moving the keyframe
along the timeline.
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Move the car again and make it stop before it hits the jaywalker.
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Make it pause again for a few frames by copying the keyframe along
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Finally, move the car along the end of the path towards the end
of the animation.
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As you play back the animation, you'll notice that although
the timing is right, the motion of the car is unnatural.
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The stop and go motion is rigid and lacks acceleration and deceleration.
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This can be adjusted in the Curve Editor.
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With the car selected, the Curve Editor can be accessed
with a right-click.
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In the Curve Editor, notice how linear the graph is.
This is because the Percent track is set to a Linear Float controller.
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With a right-click, you can choose to assign a different
controller type to it, this time choosing Bezier Float.
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Now you have nice curves representing acceleration and deceleration.
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You can make changes to the handles to fine-tune the timing.
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Play back the animation and notice the improvement.