This section details the properties of the Fan object when the Modeler is using the UE4 wind algorithm. General information on UE4 is available here.
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 max wind. Use these curves to control how the model transitions from a breeze to a storm.
The properties in this group control wind quality and the enabled state.
Press the button to launch the Wind Wizard. This tool will set up the model based on your answers to a few questions about its components.
Controls the balance between performance and quality inside UE4. Options include:
|No wind||The model will be static in UE4. 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|
Use this property to toggle wind on and off in the Tree Window.
The properties in this group control high level wind settings.
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.
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.
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.
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.
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, 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.
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.
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.
The properties in this group scale the affect 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).
Scales all wind motion distance properties (branch motion, leaf ripple, etc.).
Scales all wind motion frequency values.
Scales all direction adherence values.
Global motion refers to the uniform swaying back and forth of the entire model.
Augments the swaying affect 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.
Controls how far, in world units, the model will sway in high wind.
Controls how fast the global motion oscillates. Most models will use a low number here and higher numbers for branch and leaf frequencies.
Controls how much the model leans into the direction of the wind. Swaying occurs relative to this position.
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.
Controls how far a branches will oscillate.
Controls how rapidly branches will oscillate.
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.
Controls how much the branches lean into the direction of the wind. Swaying occurs relative to this position.
Controls how much chaotic motion is the branch direction adherence.
This property controls how likely a branch is to get “stuck” on one side of the oscillation before swinging over to the other.
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.
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.
Leaf rippling is the act of the leaf geometry vertices oscillating back and forth along their surface normal.
Controls how far the vertices will move during oscillation.
Controls how fast leaf vertices will oscillate.
Leaf tumbling is the act of individual leaf meshes rotating around their anchor point. This affect is significantly more expensive than rippling from a performance standpoint.
Controls how much the leaf rotates in the direction of the wind.
Controls how much the leaf rotates in a direction orthogonal to the wind.
Controls how fast the leaves oscillate.
Controls how much the leaves point in the direction of the wind (leaves are pointed before they oscillate).
Leaf twitching simulates the periodic flips and twists of leaves separate from the their nominal oscillations. Use these properties to make leaf motion more chaotic.
Controls how much more leaves “flip” when a twitch occurs.
Controls how often twitches might happen.
Controls how quickly leaves get in and out of a twitch.
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.
Controls how far the vertices will move during oscillation.
Controls how fast frond vertices will oscillate.
Controls how much the ripple effect is tiled across the frond. Increase this value for a tighter pattern.
When enabled, frond ripple affects the geometry normals, resulting in slower performance but better lighting (particularly better specular effects).
When “Adjust lighting” is enabled, this value scales how much the normals are modified by frond rippling.
The properties in this group control the timing and strength of random wind gusts.
Toggles gusting on and off.
Controls how often gusts can occur.
Controls how much additional wind strength is added to the nominal wind strength during a gust. Add variance to make each gust random.
When a gust happens, this value controls how long it will remain active (in seconds). Use the variance to make each gust length random.
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.
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.