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How to create falling leaves with randomly rotation - part 1 |
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We will create some falling leaves with randomly rotation driven through expressions (donīt worry - some easy expressions!).
Create a simple nurbs-plane with patching of 3 in u and v. |
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Select the plane and turn it into an emitter (F4 -> particles -> Emit from object -> optionbox). To prepare the particles for moving downwards (-y), simply set the "Normal Speed" to something like -2. Set the rate to 10-20 and hit create.
Play the animation some frames that you can see the particles. Now select the particles and add a gravity field with the settings magnitude=5 and attenuation=0. Now add a turbulence field with the settings magnitude=10 and attenuation=0.
Depending on your scale you have to vary with these settings. The goal is that the particles should tumble around and fall slowly. You also have to experiment with the "conserve"-value of the particles. I found a 0.92 to be ok. |
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For this test, create a simple poly-leaf and let it instance the particles (to do that, just select the geometry (you donīt need to select the particles) and open the optionbox from the "Instancer"-command within the Particles-menu - the default-settings should be fine, just make sure that under "Particle Object to Instance" the right particles are selected
- and finally hit create).
Now the particles are replaced with the geometry. |
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Open up the attribute editor of the particle-shape and under the "Per Particle (Array) Attributes" add a "General"-dynamic attribute. Name it something like "rotPP", Data Type has to be "Vector", Attribute Type has to be "Per Particle (Array)". Hit ok. |
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In the "Per Particle (Array) Attributes" - folder you should now see the new attribute. Rightlick on it and add the following "Creation-expression":
particleShape1.rotPP = rand (0,360);
This just gives each particle a unique rotPP-value of 0 - 360. |
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Next, you need to create a runtime-expression to control this value over time. To do that - you donīt have to close the expression-editor - simply click on "runtime" in the expression-editor and add the following expression:
particleShape1.rotPP += 0.001;
The "+=" tells Maya to add a value of 0.001 each frame to the inital value given by the creation-expression. |
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