time 0, but you want the whole scene to be filled with snow. You can add a preroll of 20 seconds to allow the particle to populate your scene before your animation begins at time 0.
Cast Shadows
Visible: Sometimes, Default: ON. This property can be changed to OFF so that the hair does not cast shadows. The hair tends to look more realistic with shadows, so this defaults to ON.
Control Points
Visible: Cache Only, Default: 2, Min: 1, Max: 25. This property determines how many control points are in the chain of each hair. The more CPs, the more the hair can bend into irregular shapes. Two is fine for short fur that just has a simple arc. Longer hair that needs to bend into S shapes and beyond will need at least three.
Dynamic Options
Default: OFF. This folder contains properties pertaining to the dynamic behavior of the hair guides.
Targeting
Default: Constraint. This option controls whether or not the dynamic chain tries to take the shape it was modeled or animated to.
None: No targeting will be performed.
Constraint: Constraints will be used to correct the bone towards the
underlying modeled or animated position. The value represents is the amount it will move towards the target in one frame. It can range from 0% to 100%. Where 0% is the same as no targeting, and 100% is completely stiff.
Spring: This method uses the a traditional damped spring using Hook's
Spring Law to encourage the chain towards the modeled or animated goal position. Frequency and damping are used to control the behavior of the spring.
Stiffness
Visible: Sometimes, Default: 50%, Min: 0%, Max: 100%, Percentage. Stiffness controls how stiff the dynamic chain acts. Higher stiffness makes the springs pull harder towards the target orientation.
Frequency
Visible: Sometimes, Advanced, Default: 1, Min: 0, Max: 1e+008. Natural Frequency is an alternative way of controlling how stiff the dynamic chain acts. When subjected to forces, this is how many times in one second, that the spring would tend to oscillate. Stiffer springs have higher natural frequency, while softer springs have lower.
Damping
Visible: Sometimes, Advanced, Default: 5, Min: 0, Max: 1e+008. Damping controls the motion of the chain. It damps the springs that force the chain towards its target. The faster the spring tries to pull, the more the damping
resists the motion. A higher number slows the oscillations more. Stiffer springs require higher damping values.
Is Rod
Visible: Sometimes, Default: ON. This option makes the targeting act like a fishing rod, the base of the rod influences the end of the rod. The end of the rod only tries to take on its intended shape and ignores the base. It tends to make whip like bends, and behaves the best if the bottom bones are either longer or stiffer than the ones at the ends.
Object Collisions
Visible: Sometimes, Default: OFF. Use this option to have the dynamic chain collide with other geometry.
Collision Radius
Visible: Sometimes, Default: 1cm, Min: 0cm, Unit of Measurement. Radius specifies the radius of the sphere at the end of the bones, which will be used to collide off of the geometry.
Bounce
Visible: Sometimes, Default: 50%, Min: 0%, Max: 1e+010%, Percentage. Bounce is often referred to in Physics as the “coefficient of restitution”. It represents the percentage of energy that should be conserved after a collision. 100% represents a "perfect" ball. It would not loose energy and would bounce forever if there were no drag. 0% indicates that no bounce should occur at all, and that all energy should be lost in the direction of the impact. Neither 100%, nor 0% are realistic.
Friction
Visible: Sometimes, Default: 50%, Min: 0%, Max: 1e+010%, Percentage. Friction is how much drag should be placed on the object as it passes sideways along a surface. 100% will stop all motion in the sideways direction, 0% will allow free sliding like ice.
Mass
Visible: Sometimes, Default: 1, Min: 0. This property specifies the mass of each of the nodes at the end of the bones.
Drag
Visible: Sometimes, Default: 1%, Min: 0%, Max: 100%, Percentage. Drag is like adding a bit of syrup to the air. It represents the amount of reduction in velocity that will happen in one second. It can be thought of as global damping
Use Gravity
Visible: Sometimes, Default: ON. This determines whether the chain uses the gravity specified in the chor.
Use Forces
Visible: Sometimes, Default: ON. This determines whether the chain uses the force objects in the chor.
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Force
Visible: Sometimes. This property provides a force or gravity to be used by this dynamic chain only. It allows you to specify an X, Y, and Z gravity that will affect the speed, direction, and distance that bones travel. Typically this will be all zeros, because the forces like gravity in the choreography will also take affect, causing the bones to fall.
Angle Limit
Visible: Sometimes, Default: 180°, Min: 0°, Max: 180°, Angle. This limits the maximum angle at which each bone of the chain can bend.
Simulate on the Fly
Visible: Sometimes, Default: ON. If ON, this constraint will compute its dynamics on the fly. The results are not accurate when going backwards or stepping forward by more that one frame. Use Simulate Spring Systems menu option from the Choreography or Action menu to store accurate results. The simulation will automatically turn this option OFF. The constraint must have simulated results in order to render accurately.
Density
Visible: Cache Only, Default: 100%, Min: 0%, Percentage. Sets the density factor of the hair.
Length
Default: 10cm, Min: 0cm, Unit of Measurement. Sets the length of the hair emitted from all child emitters. Child emitters can individually scale this value down to allow for different length hairs.
Thickness
Default: 100%, Min: 0%, Percentage. Sets the thickness factor of the hair at its root.
Kinkiness
Visible: Sometimes, Default: 100%, Min: 0%, Percentage. Sets the kinkiness factor of the hair.
Kink Scale
Visible: Sometimes, Default: 100%, Min: 0%, Percentage. Sets the size factor for the kinks in the hair.
Real-time
Visible: Cache Only. A set of properties aimed at letting the user choose between tactile real-time interaction with hair in the interface, or high quality real-time rendering. None of these settings will affect the final output.
Quality
Visible: Cache Only, Default: Shaded. Determines the quality of the real- time rendering of hair.
Don't Draw: The hair will not be rendered at all.
Wireframe: The hair will be rendered with lines using the diffuse color of the
hair material. This is the fastest rendering mode.
Shaded: The hair will be rendered taking width, lighting and specular
highlights into consideration. This is slower than displaying the hair as wireframes, but comes much closer to representing what the final rendering will look like.
Density Factor
Visible: Cache Only, Default: 100%, Min: 0%, Max: 100%, Percentage For sake of speed, when rendering the hairs in the real-time interface, the density of the hair will be reduced by this factor.
Spline Subdivisions
Visible: Cache Only, Default: 50%, Min: 0%, Max: 100%, Percentage When rendering in the interface, the splines used to draw the hair are split into individual line segments. This value determines how many line segments to use when doing so. The smaller the number, the less line segments used, causing the hair system to render faster.
Hair Systems
Animation Master now has a very exciting and powerful hair system. This system can be used for fur, long human hair, grass, plants, trees, feathers, and scales to name a few. It is extremely versatile and has about every feature needed to create unsurpassed hair.
New Material
To add hair to a model you must first create a Hair Material. Select [File][New][Material] to do this. A new Material Window will appear. This window can be closed because we will want to work with our hair on the actual model.
Change Type
The Material must be changed from a simple Attribute Material to a Hair Material. Right click (control click on a Mac) on the Attribute object under the Material in the Project Workspace Tree and select [Change Type To] [Particle System] [Hair].
Apply Material to a Model.
The Material can now be applied to a Model so we can see the changes we make take effect in real-time. Simply drag and drop the Material onto a Model or a Group on a Model. If the Modeling Window is not currently open for the Model you just applied the Material to, simply double click the Model in the Project Workspace Tree to open it.
Default Hair Material
The hair doesn't look very realistic at this point, but we are just beginning to touch on the features that allow hair to come alive.
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Draw Particles / Hair
Note: If the hair isn't visible on your Model first try pressing the <space bar> to refresh the screen. If that doesn't show the hair make sure that "Draw Particles / Hair" is turned to ON in the [Tools][Options] menu on the Render tab. This property only shows up if show advanced options is checked and the Quality is set to any of the real-time options (Default, Wireframe, Shaded). The Shortcut key for toggling "Draw Particles /Hair" ON and OFF is [Shift]+[8].
Hair System
Now that we have hair on our model it is time to customize it to fit our needs. A Hair System can contain more than one Hair Emitter. Just choose [Add Hair Emitter] from the Hair System's context menu, or choose [Duplicate] from a Hair Emitter's menu. The Hair System governs all child Hair Emitters. So changing values like Length, Density, etc. affect all child emitters. Whereas setting values on an individual Hair Emitter only affects that one. When the Hair System object is selected in the Project Workspace Tree, it's properties will appear in the Properties panel.
Hair System Properties
Preroll
Hair systems are affected by gravity and other forces when dynamics are turned on. Many times you want the hair to be in its resting state when you render the very first frame of an animation or when you are in a Modeling Window where there is no concept of time. Preroll allows you to type in an amount of time that you want the hair to be acted upon by forces before the first frame is drawn. For instance in our image below notice that the hair appears very stiff on the first frame when no preroll is applied. This is because for stiffness to take place it must be acted on by gravity. Using Preroll is necessary if you wish to see the effect of stiffness on your hair in a Modeling Window. Preroll is set to zero by default because it slows down the rate at which the hair can be drawn dramatically in many cases, especially when the hair is being groomed (the dynamics for all of the frames set in the Preroll have to be calculated to show you the results on the first frame). Usually most of your properties can be set with Preroll off, and then preroll can be turned on to adjust the stiffness of your hair or when you render a scene so your first few frames look correct, because your hair has been calculated and has reached its resting state. No Preroll / Preroll 00:01:00
Cast Shadows
Turn this option on when it is necessary for the hair to cast shadows. When this option is turned on it will slow down the render time only when you do a final quality render with shadows on in the render settings too.
Control Points
This value specifies how many control points are on each hair guide. This is where the power starts with Hair Systems. Hair guides allow you to brush or style the hair that comes out of the patches. Hair Guides will be thoroughly explained later in this document. To see the Hair Guides you must be in Grooming Mode.