Here’s how to grow a tree in Maya using a Paint Effects Brush. This assumes that you have a working knowledge of the Maya interface (you know how to access the Attribute Editor and you know what the Channel Box looks like).
1. Start Maya. Delete the preference folder and restart Maya if you like (it always ensure that no previous tool settings are left from other sessions).
2. Create a NURBS plane on the grid. Create > NURBS Primitives > Plane and scale it up by a factor of 25. Delete the history and freeze the transforms (always safe to do that)
3. Make sure you have the rendering menu set on (upper left corner drop down) and that the plane is selected and choose Paint Effects > Make Paintable.
4. Choose Window > General Editors > Visor. The Visor (don’t ask why it’s called like that) will pop. In the left column scroll down until you see the tree folder and click on it to reveal the tree thumbnails in the visor’s right window. Double Click a tree thumbnail such as TreeLeafy.mel. Very good choice!
5. If you bring your mouse cursor over to the plane in the perspective view you’ll notice that it has changed into a pencil which means that now you can paint on the plane. Give it a go! Swab a curve on the plane. Ohoh. Tons of tiny trees. Undo.
6. To make the trees bigger hold down the B key (the brush changes into a red gizmo) and scrub with your mouse left button. The red gizmo changes in size. Adjust the brush size, paint and undo until you have a tree approximately the size of your resolution gate (View > Camera Setting > Resolution Gate in the perspective view panel). You’ll notice that in order to only have one tree you need to paint a rather short curve / stroke. Go back and forth until you like the result.
7. Increase your playback range and play the animation. You’ll notice that a slight breeze makes the tree shiver. That’s not enough, we want a hurricane. Make sure you have saved your work.
8. Open the Outliner and select the tree stroke. Go to the Channel Box and scroll down to the Inputs section.
9. Click on treeLeafy1 and scroll down (you’re getting dizzy already) until you see the Turbulence attribute. I know it’s a very long scroll list and the easiest way to find the turbulence attribute is to remember that it’s next to the Turbulence Interpolation Attribute which is one of the longest names in the list. Increase the Turbulence value from the default of 0.005 to 1
10. Make sure you are playing your animation in real time and not ‘every frame’. Go to the preference settings to check on that please). Wow! That tree is tormented! Decrease the turbulence value if you prefer to a conservative 0.5. Play the animation again.
11. At this stage you can hide the plane if you want: turn it’s visibility attribute to off or press CTRL-H. You can also change the environment color to white (the tree won’t render very nicely against black). I also suggest you place a directional light in the scene. And do a couple of test renders. Looking good.
12. Let’s make that tree grow! Select the tree stroke (in the outliner maybe) and open the attribute editor. Select the treeLeafy1 tab there and scroll down until you see the Flow Animation folder. Open it.
13. Check the Time Clip attribute (on) and bring the value of the Flow Animation attribute to 1. Play your animation. The tree should be growing. Although the slider goes up to 1 you can input a higher value manually.
14. Render your sequence and watch it in fcheck. Yew!!!! The bark on the trunk is all flowing and disgusting! Go back to the Flow animation attributes and uncheck the Texture Flow attribute. Re-render.
15. Et voila. Tree growing in the wind. Finished scene file here