Moving Objects over time within a Scene is accomplished using Spatial’s Motion Path feature set. You’ll explore the use of Motion Paths by giving flight to some birds within the Aviary Scene.
- Open the Aviary Lesson 5 Scene located in the Lesson 5 assets folder.
In this Scene, you should find the Sparrows group with its parent Object at the origin.
Take a moment to familiarize yourself with the sound of these birds.
NOTE: If you have not downloaded the associated Lesson 5 assets, please visit the Resources page in Lesson 1.
- Solo the Sparrows and play the Scene.
You can hear that the birds are already set to loop.
- In the Inspector, expand the Position area.
You’ve worked with the Position area before when you’ve set the static position for Objects in previous lessons. At the top of the position area you can see the ‘Sparrows’ is currently at an X, Y, Z position of 0, 0, 0.
Further below you’ll see a table called the motion point list that also shows a matching X, Y, Z of 0, 0, 0 that’s displayed in row number 1. Row number 1 will always reflect the static position entered at the top of the Position area and by default represents what can become the first point on a Motion Path. A Motion Path plots the trajectory for how an Object moves over time through the Scene. To actually create a Motion Path, there needs to be at least two motion points associated with an Object. New motion points can be created using the [+] symbol to the lower left of the Position Area.
- Click the [+] symbol in the lower left of the Position Area to create a new motion point.
A new motion point is created and it’s represented in the motion path list on the second row. In the Canvas, you’ll also see a spherical icon with the number 2 that represents where the second motion point is located in the Scene. A Motion Point for an Object can be positioned in a Scene by moving it in the Canvas, just as you would to move an Object, or by changing the X, Y, Z values that are displayed for that motion point the motion path list.
TIP: If you’re unable to see the motion point, use the view options dropdown to enable motion points.
- Move the motion point to the front upper right front of the room boundary, a position of 4, 4, 4.
Now you can clearly see the motion path’s trajectory displayed as a line.
Play the Scene, but be sure to play from the beginning of the Scene’s timeline. Pressing Return will return the Scene’s playhead to the beginning.
- Press Return and play the Scene.
In the Canvas you see the Object’s tetrahedron travel from motion point 1 to motion point 2 over the course of 1 second, and as it flies, you hear the birds move from the upper-left rear of the space to the upper-left front.
Changing timing between Motion Points
The birds are flying fast! It only took 1 second for the birds to fly between the motion points. This is because the default time to transition to the next motion point in the motion point list is 1 second. It can be difficult to get a sense of time transitions when looking at values in the motion point list. To make timing easier to understand motion points are displayed in the lower timeline found underneath the Canvas. Currently it’s difficult to see the timing relationship between motion points 1 and 2 because the scale of the timeline is too broad. You can zoom the time scale using the Zoom Slider.
- In the lower timeline, drag the Zoom Slider to the right.
You see motion points represented as circles, and the numbers within each circle correspond to the motion point list.
Changes to values in the motion point list are reflected in the lower timeline. Slow down the bird’s flight by changing the duration to 2 seconds.
- Change the Start time of motion point number 2 to 2.0 seconds by dragging it forward.
Notice that the duration changes in the inspector follow accordingly.
Motion points can also be added directly in the Canvas.
- In the Canvas, right-click the second motion point and choose Motion Path → Add Motion Point.
A new motion point appears with a position that continues on the previous path.
- Move the new motion point to the upper left front of the room boundary (-4,4,4) and play.
Notice the duration value of Motion Point 3 is the default 1.0 which is also reflected in the lower timeline.
When dragging a motion point in the timeline, the motion points on either side will remain anchored to their time position. As a result, the duration times will adjust automatically.
- In the timeline, drag Motion Point 2 to the left until it’s half way between Motion Point 1 and 3.
You can see that motion points 1 and 3 stayed in their position.
You may want to adjust the timing of a motion point so that the relative position of points occurring later in the timeline maintain their relative distance. This is sometimes referred to as a ripple edit in non-linear video editors. This can be done by adjusting the start time of a motion point in the motion point list, instead of making the change in the lower timeline.
- In the motion point list, raise the start time of motion point 2 to a value of 1.5.
You see that this time that motion point 3 maintained its relative timing to the new position of motion point 2 and moved back in time.