Fan - Legacy UE4/Unity
This section details the properties of the Fan object when the Modeler is using the Legacy UE4/Unity wind algorithm.
Note
Any property with a curve means it varies according to wind strength. The left side of the curve is the value when there is no wind and the right side is the value at maximum wind strength. Use these curves to control how the model transitions from a breeze to a storm.
Main
The properties in this group control wind quality and the enabled state.
Enabled
Use this property to toggle wind on and off in the Tree Window.
Mode
Change the style of wind applied to the model. This style should be based on the target application, not the algorithm that may look the best on the model.
Preset
Controls the balance between performance and quality inside UE4/Unity. Options include:
| Preset | Description |
|---|---|
| No wind | The model will be static in UE4/Unity. Fastest, lowest quality |
| Fastest | Only global sway will be applied to the model. |
| Fast | Global sway and leaf ripple are applied to the model. |
| Better | Global sway, branch motion, and leaf ripple are applied to the model. |
| Best | Global sway, branch motion, leaf ripple, and leaf tumbling are applied to the model. |
| Palm | Global sway, branch motion, leaf ripple, leaf tumbling, and frond ripple are applied to the model. Slowest, best quality |
Actions
Wind wizard...
Press the button to launch the Wind Wizard. This tool will set up the tree based on your answers to a few questions about its components.
View docs...
Opens a web browser to the online documentation for the current wind mode.
Settings
The properties in this group control high-level wind settings.
Strength
This property sets the strength of the wind. 0.0 corresponds to no wind, 1.0 corresponds to the highest wind.
Note
The actual wind behavior is governed by how the properties below interpret the strength value. It is possible to have some wind at 0.0 and no wind at all at 1.0, depending on how the properties are tuned.
Response Times
These properties control how quickly the model responds to changes in wind strength and direction. Large, heavy models should have large response times. Small, light models should have short ones. For example, if a flower and an oak tree are placed under the influence of the same wind source, the flower should react more quickly to changes in that source than the oak tree does.
Strength
Sets the response time for strength changes. It is measured by how long, in seconds, it would take the model to go from 0.0 behavior to 1.0 behavior.
Direction
Sets the response time for direction changes. It is measured by how long, in seconds, it would take the model to react to a 180-degree change in wind direction.
Wind Anchor
The wind anchor is used only in conjunction with the "Palm" preset. The wind anchor is a point in space that moves around based on strength, direction, the shape of the tree, and the values of the properties in this group. Branches and fronds that use the wind anchor will bend toward this point when the wind blows. The wind anchor is indicated by a cyan dot near the tree.
Vertical offset
By default, the wind anchor will position itself at a height halfway up the model. Use this property to adjust its position up or down on the Z-axis.
Distance Scale
The wind anchor will be positioned at a reasonable distance from the center of the model in the current wind directions. Use this property to scale that distance. Keep in mind that distances too far away from the model will lead to pronounced skewing during wind animation.
Scalars
The properties in this group scale the effect of several wind properties across all wind motion categories. Use these scalars to make sweeping changes to the entire animation (e.g., speed the whole thing up with a frequency scale).
Distance
Scales all wind motion distance properties (branch motion, leaf ripple, etc.).
Frequency
Scales all wind motion frequency values.
Direction adherence
Scales all direction adherence values.
Global Motion
Global Motion refers to the uniform swaying back and forth of the entire model.
Height exponent
Augments the swaying effect towards the top of the model. Increase this value to add some curvature to the swaying motion. The Skewing caused by this is somewhat (but not completely) corrected by the shader.
Distance
Controls how far, in world units, the model will sway in high wind conditions.
Frequency
Controls how fast the global motion oscillates. Most models will use a low number here and higher numbers for branch and leaf frequencies.
Direction adherence
Controls how much the model leans into the direction of the wind. Swaying occurs relative to this position.
Branch Motion
The properties in this group control the movement of the branches where "Wind:Apply" is checked (the first such branches from the Tree generator). These are the properties that control independent branch motion.
Distance
Controls how far branches will oscillate.
Frequency
Controls how rapidly branches will oscillate.
Whip
Enables this property to make branches appear more "rubbery", as if a whip were being cracked in slow motion. The value controls how flexible the branch appears to be.
Direction adherence
Controls how much the branches lean into the direction of the wind. Swaying occurs relative to this position.
Turbulence
Controls how much chaotic motion is the branch direction adherence.
Sway bias
This property controls how likely a branch is to get "stuck" on one side of the oscillation before swinging over to the other.
Sway freq
This option controls how often "sways" from one side of the oscillation range to the other occur.
Note
The two "sway" properties in this group combine to make the oscillations more complex than a simple sine wave.
Leaf Motion
The properties in this group control the behavior of leaf meshes.
Note
Some of these properties may be hidden for performance reasons based on the "Preset" selection.
Ripple
Leaf rippling is the act of the leaf geometry vertices oscillating back and forth along their surface normal.
Distance
Controls how far the vertices will move during oscillation.
Frequency
Controls how fast leaf vertices will oscillate.
Tumble
Leaf tumbling is the act of individual leaf meshes rotating around their anchor point. This effect is significantly more expensive than rippling from a performance standpoint.
Flip
Controls how much the leaf rotates in the direction of the wind.
Twist
Controls how much the leaf rotates in a direction orthogonal to the wind.
Frequency
Controls how fast the leaves oscillate.
Direction adherence
Controls how much the leaves point in the direction of the wind (leaves are pointed before they oscillate).
Twitch
Leaf twitching simulates the periodic flips and twists of leaves separate from their nominal oscillations. Use these properties to make leaf motion more chaotic.
Throw
Controls how much more leaves "flip" when a twitch occurs.
Frequency
Controls how often twitches might happen.
Sharpness
Controls how quickly leaves get in and out of a twitch.
Frond Motion
Frond animation is achieved by oscillating frond vertices along their surface normal in a manner similar to leaf rippling. This motion is available only when using the "Palm" preset.
Distance
Controls how far the vertices will move during oscillation.
Frequency
Controls how fast frond vertices will oscillate.
Tile
Controls how much the ripple effect is tiled across the frond. Increase this value for a tighter pattern.
Adjust lighting
When enabled, frond ripple affects the geometry normals, resulting in slower performance but better lighting (particularly better specular effects).
Lighting scalar
When "Adjust lighting" is enabled, this value scales how much the normals are modified by frond rippling.
Gusting
The properties in this group control the timing and strength of random wind gusts.
Enabled
Toggles gusting on and off.
Frequency
Controls how often gusts can occur.
Strength
Controls how much additional wind strength is added to the nominal wind strength during a gust. Add variance to make each gust random.
Duration
When a gust happens, this value controls how long it will remain active (in seconds). Use the variance to make each gust length random.
Response Scalars
Rise
This value scales how long it takes for a gust to reach its maximum value. Lower this value to increase the speed at which gusts impact the model.
Fall
This value scales how long it takes for a gust to return to the nominal wind level. Lower this value to increase the speed at which the model returns to nominal wind conditions after a gust.