You can see that, instead of 900 in the z-axis orientation, we have rotations set in all axes.
Although this results in the same endpoint orientation, this is no good for animation since the rotations
in all the other axes are also being interpolated resulting in a very different movement than that which
Because rotations are not commutative (i.e. the endpoint depends on the order that the rotations are carried out in) the Euler system always performs rotations in a set particular order: z then x then y. So, if you try and rotate something around the x or z axis, you might not (as in this case) get the result you expect.
The wheels are parented to their respective axles. The axles here are Null objects and, because of that,
the rotations were carried out in a slightly different way to that described above. This is described below.
The axles, together with the mudguards and headlights, are parented to the car body and this, in turn, is parented to a Null object. This top level aids things later when we come to animate the car - due to the same principles described in the last section, this Null helps keep the orientation as we want it.
To establish all the proper parenting relations, make sure each object has a Position and Rotation Track, move the time marker to 0, select all objects and choose Animation -> Keyframe Modified Tracks of Selected Objects.
Select the appropriate object and curve from the list (in our case there is only one of each).
Make sure the Orientation Follows Curve box is ticked to automatically rotate the car in the right direction as it travels along the curve.
Keyframe Spacing allows you to specify whether the car moves at constant speed or whether it accelerates. Choose Constant Speed for now; acceleration is covered later.
Below this, the dialogue tells us the Curve Length. Make a note of this - we'll need it in the next section.
The next set of entries allow you to specify the speed, acceleration etc. As you enter data in some of the boxes, AoI automatically calculates and updates values in other boxes. In this animation, we want the car to take 5 seconds to get around the circuit so set Start Time to 0 and End Time to 5. The following Speed box is then updated.
Press OK to accept.
|We want the lights to switch on/off suddenly rather than fade in/out so select Discontinuous for the Smoothing Method.|
The parameter here is called 'headlight on' and it will be equal to 0 when the headlight is off and
1 when it it on.
This parameter is used to switch between 2 simple 'textures'; a plain, dull grey when 'headlight on' equals 0, and a yellow emissive texture when 'headlight on' equals 1.
The parameter is simply used as the scaling factor in 2 colour scale modules (1 indirectly). When 'headlight on' equals 1, the scaling factor for the yellow colour is 1 and the scaling factor for the grey colour (given the by expression 1-headlight on) is 0 and vice versa. The colours are then simply summed using an Add module so that there is a single output to plug into the Diffuse colour property box. The yellow colour is also plugged into the Emissive colour box to give the illusion that light is being emitted.
The top part of the dialogue allows the name to be edited and the Smoothing Method to be
defined. As with the spotlight, we want the texture to change instantaneously so select
The lower part of the dialogue lists all the available texture parameters. In our case, there is only one: 'headlight on'. Select this and click OK.
Now, set a keyframe for each headlamp in the Texture track at time 0. Double-click this keyframe to display the dialogue below. Here you can set the value of any parameters selected in the track options previously. In out case, we want to set the value of 'headlight on' to 0.