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Chapter 20. Advanced Particle Animation > Multiple Objects Using FX_Linker

Multiple Objects Using FX_Linker

The FX_Linker is a tool that enables you to take any object and use it to replace particles. Think of flocking birds, falling dollar bills, or blowing leaves, to name a few. FX_Linker gives you the power to select one object and blend it with particle effects.

Exercise 20.3 Animating Blowing Leaves

Liquid is not the easiest thing to create in 3D, but the power of LightWave’s particle engine and a fair amount of tweaking in Hypervoxels can get you the desired results. How about using particles to create blowing objects, like snow, rain, or leaves? This next exercise shows you how to create realistic-looking blowing leaves.

Clear Layout, and then add a HVEmitter and a wind controller.

Select Move from the Items tab (t), and move the wind out of the way to see your particles, making sure to create a keyframe for it, to lock it in place.

Open the Properties panel for the wind, and set the Falloff Mode to OFF. This will create a wind source for the particles, no matter where it is located.

If you chose the Falloff Mode to be Linear, for example, the wind would need to intersect with the particles. Figure 20.13 shows the ParticleFX Wind panel.

Figure 20.13. The Falloff Mode in the ParticleFX Wind panel is set to OFF so that the particles are affected no matter where the wind source is located in the scene.

Set Layout’s last animation frame to 300 for a 10-second animation. Press the Play button. The particles drift upward. The wind by default is pushing up.

Select the Wind controller in Layout, rotate it 90 degrees on its bank, and create a keyframe at 0. Press Play again, and you’ll see the particles pushed to the side.

The particles end too soon, so open the HVEmitter property panel. Set the Birth Rate to 30. Then under the Particle tab, set the Life Time to 300, and a random value (+/–) to 60. Figure 20.14 shows the settings.

Figure 20.14. Make a few adjustments under the Particle tab, and the particles are almost ready for some leaves.

Bring the Particle Resistance down to 0.5 so the particles move throughout their lifetime. Then, click the Motion tab and set a Vibration of 1.0 to shake up the particles.

Lastly, click the Generator tab, and click the small button labeled Fixed in the bottom left. This allows you to set a specific start time for the particles. Set the value to –150.

This entry will set the particles in motion 150 frames before 0, which is the start of the animation. The result is that the particles are already in motion from the emitter. They are not starting out from the emitter in the beginning of the animation.

Now back in Layout, under the Items tab load the Leaf_clipSub object from the accompanying CD. This is nothing more than a flat subpatched object with a clip map of a leaf. Figure 20.15 shows Layout. You might need to zoom out slightly after the object has been loaded.

Figure 20.15. A flat polygon is all you need to begin creating a frame full of blowing leaves.

Select the leaf object and press the p key. Set the Subdivision Order to Last under the Geometry tab for the leaf object. Set Display SubPatch to 1, and leave Render SubPatch set at 3.

Click the Deformations tab, and then click the T button for Displacement Map to enter the Texture Displacement Map Editor.

Change the Layer Type to Procedural. The default Procedural Type is Turbulence, which is fine. Just change the Texture Value to 0.25. Lastly, click World Coordinates (see Figure 20.16).

Figure 20.16. A procedural displacement map on the leaf object bends it up a bit.

What you’ve done here is put a fractal displacement map on the leaf object. This will rough it up a bit, so it’s not perfectly flat. Setting World Coordinates will tell the object to move through the texture, rather than animate the texture on the object. You’ll see how this affects the leaf shortly.

Click Use Texture to close the Displacement Map Texture Editor. Close the Object Properties panel if you haven’t already done so.

Now select the leaf object, and scale it down (Shift+h) to 0.2 for the X, Y, and Z. Create a keyframe for it to keep the new size. Figure 20.17 shows the change.

Figure 20.17. Sizing down the leaf object gets it ready for some blowin’ in the wind.

Now the fun part begins. Make sure that the leaf object is selected, and from the Scene tab, click the FX_Linker button. The ParticleFX Linker panel appears, allowing you to replicate the leaf object for every particle in the scene. More importantly, it automatically adds the FX Link Motion modifier to each object (see Figure 20.18).

Figure 20.18. The FX_Linker panel allows you to replicate objects instantly to replace particles.


Always save your scene before performing operations like this! There is no undo, which means that if you want to change anything after the fact, you’ll have to go back and reset your particle scene.

Because the leaf object was selected when you opened the FX_Linker panel, the object is automatically listed as the Replace Object in the upper-right corner of the interface.

The emitter in the scene has a maximum of 1,000 particles, emitting 30 of them every second. That’s 30 leaves every second up to 1,000. The best option here is to go back to the emitter and lower the Birth Rate. But for now, you can just replicate fewer leaves. Too many might bring your system to a halt.

At the right side of the FX_Linker panel, the Copy area lets you add a value. Add 100. This will create 100 copies of the leaf object, replacing the first 100 particles with it (see Figure 20.19).

Figure 20.19. Set the Copy value to 100 for 100 leaves.

Set the Random Rotation Min values to –60. The three value areas from left to right are X, Y, and Z.

Set the Random Rotation Max values to 90 for the X, Y, and Z.

Leave Random Scale values all to the default 1.0.

Set the Random Spin Min to –60 for the X, Y, and Z, and the Random Spin Max to 90 for X, Y, and Z (see Figure 20.20).

Figure 20.20. A few minimum and maximum rotation values in the FX_Linker panel will help the blowing leaf effect.

Click OK to close the panel. Your system will hang for a moment as LightWave calculates the changes. Figure 20.21 shows all the leaves now attached to the particles!

Figure 20.21. The FX_Linker easily replicated 100 leaves and attached them to particles.

Switch to Camera view, and move the camera into the frame so that it’s filled up with leaves. Figure 20.22 shows the shot.

Figure 20.22. Because you set the particles to start at frame –150, the camera at frame 0 sees the leaves right away.

Move the timeline slider back and forth and take a close look at the leaves. They almost look like they’re swimming through the air, sort of floating like a falling piece of paper. This is the World Coordinate setting for the Displacement Map you applied earlier. As the particles move the leaf objects, the leaf objects are moving through the displacement. This creates a nice, flowing look.


Because the polygon count in the scene now has 100 copies of the leaf object, you’ll need to crank up your Bounding Box Threshold to see some of the objects while moving the timeline slider.

Move the camera up and in to get a good view of the scene. Create a keyframe to lock it in place. Press F9 to render a test frame.

With the Leaf object selected, press the p key to open the Object Properties panel. From the Rendering tab, click the T button for Clip Map. Set an image map the way you normally would, using the leaf2.tga image. Add the image on the y-axis, and click Automatic Sizing.

Press F9 to render a frame. You’ll see the leaf render, but not the white area! The image is clipped out (Clip Map, Object Properties panel). Figure 20.23 shows the rendered frame with SkyTracer2 added for a backdrop.

Figure 20.23. Using FX_Linker with a single clip mapped object, you suddenly have a view filled with blowing leaves.

From this point, you can enhance the animation with a little motion blur, more wind (such as wind gusts), and perhaps a secondary set of leaves of a different color. But the example here is a great way to get your multiple objects in motion. The FX_Linker is very straightforward as you’ve seen, and it is useful for replicating objects for your particles.

FX_linker allows you to add the FX_Link Motion modifier to a mass of objects and set randomized settings. You can use FX_Linker to create swarms of bees, bats, birds, whatever you like! The setup involves adding your Particle emitter and getting the particles to move the way you want them to. Then load the object, or use Load From Scene to load a scene of a bird flapping its wings. Select the main parent or root of that flapping bird, open FX_Linker, and set it up. The flapping bird, its wings, and so on, will be copied and assigned to the particles.

Now move on to another tutorial using FX_Linker and collision objects.



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