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The third wish from the genie:
Light stream & some other effects
This is the third and final part of my Genie Series tutorials. Now everything is ready: the genie is coming out soon.
Andrew Kramer had written a tutorial about similar effects while I was buried under tons of projects. I thought I could make my tutorial mainly focus on the flow and some details.
BTW, to finish this tutorial with AE6.5, Trapcode Particular & Trapcode Starglow filters will be needed.
Now please open the project we made last time, and we'll get started.
In this project we are going to create a light stream coming out from the lamp to swirl around this scene. Because in most of the process, the camera is moving and the light stream is out of view sight, it's hard to imitate it with a 2D layer stream. On the other hand, AE doesn't have a 3D modeling function, so we have to find out some other strategies.
Trapcode Particular 1.5 has developed a new function. Now it can make a particular system moving through a certain 3D path. It means that we can create a stream by animating a particular system.
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Step 1: Create the motion path
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Create a red solid layer, and name it as "guide". Set its size as "40*40". Check on the 3D layer switch. Set some key frames for its position property. The path might be like this:


The shape of the path will be the shape of the light stream, so make it smooth if you don't want to make a light stream with sharp corners.
Preview the animation, adjust the path and speed of the layer "guide" until you are satisfied with them.
Now create a new point light, and name it as "motion path 1". Copy the key frames of the guide layer and paste them in to the light's position property. In fact the guide layer is useless now, we can delete it or hide it. After that, hide the light.
BTW, you can also create the light and the path directly without making the guide layer, but I think a solider layer can be rendered and adjusted quickly. It's nothing but a trick of animating something that can't be rendered.
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Step 2: Create particular system
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Create a new solid layer whose size is the same as the comp. Apply the filter Trapcode/particular to this layer.
Open the emitter settings, create these expressions for the "positionXY" property and "positionZ" property:
positionXY:
temp = thisComp.layer("Motion Path 1").position.valueAtTime(0);
[temp[0], temp[1]]
positionZ:
temp = thisComp.layer("Motion Path 1").position.valueAtTime(0);
temp[2]
Set the "emitter" settings like this:

Set the "Particle" settings like this:

Set the "Physics" settings like this:

Please pay close attention to the motion path property. If you can't set it, check the name of the light layer.
Now we get an effect like this:

Many light balls move along the path and forming a light line.
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Step 3: Develop the Particular System
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Then we are going to turn the line into stream. I found that in many similar effects, the light streams are made of some texture like this:

But here we have some textures like this:

The key point of this problem is how to replace the balls as some other shapes. One would think that we could settle this problem by using custom particular shape. But in fact, it can't work here.

We can try to image that many balls in different sizes make up a stream. It's like this:

So I decided to try making it with "Aux System". Set it like this:

Here we get a result like this:

Not so good, but it's better now. Because we only need Aux System to make up the stream, the particulars are useless here. Although we can't delete it, we can hide it. Set the "opacity" property in "particle" as "0".
It's gone, and we get this:

Why do we only get a line? It's because the velocity of the particule is 0. Go to the "emitter" settings and replace it with "20".

Immediately, our effect changed. It looks much better now, but some part of the stream seems broken now. Go to Aux System setting and replace the property of "particles/sec" with "510":
Preview the animation, you find that the stream will come out endlessly. You can fix that by adding 2 key frames to the "particle/sec" property, and turn off the particle system at certain time.
Now the stream seems too regular, so we can add some chaos factors. Go to the "physics" settings, and set the property "spin amplitude" as "20".
Now we get a result like this:
Now, our effect is almost finished. All we need to do is simply fix some details as we like.
These are my settings:
BTW, don't forget to turn on the motion blur switch.
After adjusting the levels of the stream:
To tone the color, we have many tools in AE. But this time I want to try another filter of Trapcode.
Apply Trapcode/starglow to the stream.
Even the default settings can work very well:
Before the end of this tutorial, we can also try the presets of Trapcod Particular to create smoke, light spring and some other things to decorate our scene.
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