Paint effects animation in Maya

Hi, welcome to the second part of the series of Paint Effects Articles. My name is Isidro Fernandez, and I want to say thanks to all of you for the comments I received from a lot of people who want to learn a little more. I'm really satisfied with the comments and suggestions and thanks to that, here is the second tutorial and I will teach you how to create animations with Paint Effects and how to simulate some real forces in your scenes and also some growing simulations.

First, I want to make a little introduction to the possibilities that paint effects has in terms of animation. This will be a medium level tutorial, so is better if you have a previous knowledge of paint effects or you can read the first tutorial here.

Here is the animation of the project we are going to create. It is a simple animation of blowing wind moving some grass, the clouds and the trees in the background, some texture animation and a simple growing simulation for the tree in the front.



Something I have to remark on is the fact that the only geometry that this scene has is the ground, everything else is done in the postproduction process that uses paint effects for rendering (see image), amazing right!, well it's more amazing the rendering time, it takes about 1:08 seconds to render for one frame!!!, and you can see a lot of geometry there.

Paint effects are something like a particle system, and that it's some of the things that let us created so many possibilities. Let me say some that come in to my mind right now, we can create animated clouds, we can create vegetation, and trees that we can turn into polygons and then use another render system like Mental Ray for rendering and conserve the animation we created in the paint effects system, we can create water simulations, hair that can be animated in an incredibly realistic way, we can make that every step of our characters deform the grass when they walk, we can animate the paint effects and then make them emit particles (I can't imagine how many possibilities this can generate), you can make the tubes behave like springs, you can create so many things and in so many easy ways

Well now starting with the scene, I will share my files with you, so you can explore the settings I use

First Stage: Set up your scene

I made a simple sketch of the image I wanted and then I created the terrain and applied some materials. After that I set my camera and once I have this ready, I can start to work in how I want to apply the paint effects into my scene.

In this tutorial I created the grass, the trees and the clouds in the same way that I show you in the first part of the tutorial, so I will not go deep in that here. I will explain better the clouds stroke, and some thing about the trees, but the important thing here, is the animation.

So lets get started.

I start painting the grass in the terrain, and then I change the settings until I get the shape and colors that I want. Here you can see part of the process (again I will show this really quick).

Here is the geometry I will use

This is the angle of the camera

Here you can see the terrain geometry with some simple shader.

Here is the first pass of paint effects, the grass.

Here you can see the grass in the shot.

And now after configuring my settings, here is the actual render of my grass.

Second Stage: Wind Simulations

Now I want to simulate some wind effecting the grass and for that I can use some different techniques. Here I will explain the animation attributes from the paint effects stroke settings, but we can use control curves and make it react to field forces from the dynamics system in Maya 7, or you can turn it into polygons and then make it soft bodies and make it react to forces as well, but here I will show the stroke settings for the animation in the paint effects system

In this image you can see the tree mayor animation sections for paint effects, the first one is the Behavior sections, which will have the subsections of displacement, forces, turbulence, spiral, and bend. The second is the Gaps section and the third one is the Flow Animation section.

These are the settings made to control a lot of the aspects for the animation behavior, but you have to know that you can set keys in every single panel, from shading to number of branches, you can animate almost everything, so be creative, there's no limitation. I will show you some examples of that in the tree growing simulation.

Well, first I will explain the settings from the Behavior section and then I will show you how to configure this settings for our grass wind simulation. The Behavior panel is inside the creation panel.

Here we are going to start exploring the Turbulence panel, here is the image.

You can find this section in Tubes > Behavior > Turbulence.

We have some really interesting settings. First we can choose our force type, this will let us to create the kind of force we need, for example the local force is better for animating individual objects, and the word force is better is we want to share our forces in another brushes. I will go and use the 'Grass Wind' type. This kind of force makes more turbulence and effects the tip of the tubes and has less effect on the roots of the tubes. Creating some really nice wind simulation.

Then we can choose the interpolation that the mathematical method used to smooth the motion in the animation.

Turbulence, defines the air speed due to turbulence.

Frequency, defines the amount of variance in the turbulence.

Turbulence Speed, defines how quickly the turbulence changes over time.

Turbulence Offset, offsets the position of the turbulence

These are the general settings for the turbulence section, working with this settings we can get some really nice simulations, now back to our scene, here are the settings I will use for my wind simulation in the grass.

As you can see in my settings, I already have some keys added to this section, so let explore this settings. I will use wind turbulence and smooth over time and space for may initial settings, so I went to frame 1 and set a key for 'turbulence', Frequency', and 'Turbulence Speed', and this will be a soft wind animation. I use really low values, like 0.16 for 'turbulence' and 'Frequency', and some really low values too for 'Turbulence Speed', maybe some between 0.3 to 0.5. Then go to frame 300 and set keys again, this time with some 'high' values, but again this is a wind simulation and is kind of soft so I will use maybe some settings around 0.2 in 'turbulence' and 'Frequency', and set the 'Turbulence Speed' a bit higher too.

This is really simple for teaching reasons but, for a realistic simulation you will need to introduce some more keys and use a lot of different values in order to have a rich scale of movement and deformation, and to simulate the behavior you need. This always will be different, for a nice day or a stormy wind, you need to explore a lot of the settings and search for what you want to simulate.

Another thing is that you can control the curves of this animation in the Graph Editor.

I will use two kinds of grass, and I will animate the second grass in the same way I animate the first one, but I will use a different values to have more randomness and movements. You can see I actually did a little bit of the work, but these simple settings I use to simulate, is a great way for the wind forces. Of course in order to have more control you have the entire panel of behavior to explore, here I am using only turbulence, but you can animate and use Displacement, Forces, Bend and Spiral not only to animate, you can use this sections to help to construct the shape of you paint effects and created more rich forms and nice deformations.

In this scene I created a forest in the background and I use the same method to animate this, you can see that it is exaggerated a lot but you can see it's actually moving, it's the same Turbulence animation but this time I use 'the tree Wind' type, and really low values, kind of 0.021 because this type of turbulence is a little more stronger and you whatto apply more turbulence to the branches, so it's simulating the real tree wind deformations. For this I use the Oak Forest stroke As you will see this kind of stroke has no branches but again, I use 'the tree Wind' type for teaching reasons.

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Third Stage: Grow Simulation

Now lets move on to another great thing for paint effects and the grow simulation. I will create a simple tree; I will use the Oak White stroke. See here the images.

In this sequence I will animate a growing tree, (it's not too realistic because is only for illustration purposes, if you want to created a realistic vegetation growing simulation you will need to research the real process and create a lot of really defined keys for that, but again you can apply this principles I will show for simulating a lot of great effects not only for vegetation simulations, you can combined with particles and create amazing effects), in order to proceed I will explain the Flow Animation section from the stroke. One important thing is that these sections have direct influences over gaps, twists, and textures move.

Flow Speed: This defined the speed, in cycles per second and direction for gaps, twists, and textures moves, and controls the speed that the tubes grow. You can use negative numbers to inverse the movement.

Textures Flow: This moves the texture down the tubes.

Stroke Time: If you want this option to work, Time Clip must be on. This option will let you animate the tube growth and flow from the beginning of the growth simulation to the end of the growth simulation.

Time Clip: Using Stroke time on, the animated tubes first appear and begin to flow at the time set by Start Time, and die at the time set by End Time.

If Time Clip is on, but Stroke Time isn't, tubes along the stroke path are already planted, which means the tube growth is uniform.

Also define when the tubes appear or born during the grow simulation and when they die. (Start time, end time).

Start Time: this indicates when the tubes appear, but is set in seconds, so if you are working in 24 frames per second and set the start time to 1, the strokes appear in the 24th frame, you can use decimals to set the right number.

End Time: This option defines when the tubes disappear, again is set in seconds, and if you are working with growing simulations try to set this number really high, so you don't get the tubes starting to disappear when your animation is not finished.

Time: Use this option to key frame time. For example, if you are animating the growth of a tree, you can make the tree remain a sapling for the first 100 frames of the animation, then have the tree grow from a sapling to a full grown tree in the next 100 frames.

Now that we know what every option does, let's animate the tree:

For this animation I will make it a little more interesting, I will animate the grow simulation, I will animate and the way the tubes grow, and I will use some wind forces too. So let's start.

First I will animate the grow simulation, by setting the stroke time and time clip on, and the texture flow off, this is because I don't want to animate the texture of my tree, I will set my speed to 0.6, and I will set my start time to 0, so my animation starts in frame 1, and set my end time to a really high number, because I don't want my tree to disappear in this animation.

And believe it or not, that's it, now my tree will grow, of course its not going to be an excellent animation we have almost no control of anything, so I will set my control keys to the tree so the leaves will be really small when they born, and the branches will be very thin, and the width of my tree will be really thin in the beginning and at the end it will be a really big one. Now the question is how I will do that, and it's really easy don't start to panic, you only have to set the keys for the settings you want to correct in the creation section, see some of my values here.

For a real animation I will probably set more keys in more values, so I can control the entire behavior of my animation, and for each value I will set deferent keys in a lot of different values.
See these keys in my graph editor here; I have set keys for, the split range, and angles

Now lets see how the tree looks in different frames.

As I said before, this is a really simple simulation, and you can actually set keys to every one section in the paint effects.

Well now I will create a simple tree wind simulation too, and its done in the same way I did the animated grass wind, see the settings I use.

I use the tree wind type, and as I said before because this applies more turbulence to the branches and leaves, remember you can animate the forces, blend and spiral settings too, in order to created a really great effects.

Now, what about the clouds in the scene.

Yes, more Paint Effects

See how the cloud looks in the 3d view of Maya 7 and compared with the render version. Nice right!!

Well there are some limitations in clouds but first I use the Cumulus Purple stroke, but how do I animate the clouds moving?

If you try to apply turbulence or wind deformation you will see that actually you can't do it. You can't use any of the behavior settings!!!!. You can use the Flow animation panel but I will not, so how I animate my clouds if I do not use any of the animation settings for paint effect?

Well is really easy I animate my texturing settings, I animate my Repeat U, Repeat V, Offset U and Offset V settings from the texturing section in my paint effects, I can also animate the colors and well again a lot more.

See the settings I use here.

In this simple example I only set one key to the beginning and one in the end and that's it. Of course you need to configure your brushes; experiment a lot, there is a lot of possibilities with this.
I will not write the values I use because that's not the idea; I'm showing the general technique to use not restricted to values, that's kind of boring, you need to learn how to do it, not how to copy some settings from an article. Again experiment. Create your own techniques and help us to learn from you too.
Here you can find the maya files and the animation file to download

animation

maya files

Well I hope this article can help you, now if you want some other tips or tutorials write to me and tell me what you will like to learned , and as I did with this article, I will try my best to help you.

Thanks a lot for you attention, bye

Isidro Fernandez C

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