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windvfx [2020/03/31 10:24] – external edit 127.0.0.1windvfx [2023/04/03 18:30] (current) – steph.jorgensen
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-====== VFX Wind ======+====== VFX wind ====== 
 +"VFX" wind mode is used to create the highest quality wind animations.  It is previewed in real-time in the Tree Window but is not currently supported in any real-time engines due to its complexity.  Use this wind mode to export point caches for FBX, Alembic, and USD files. 
 + 
 +>**Note:** Focusing on a single branch of a complex model is often the best way to preview fluid motion in the [[tooltree_window|Tree Window]]. 
 Wind animation is controlled by editing the properties on the [[fanvfx|Fan object]] and the wind properties of each generator in the model (e.g., [[branch_generator#wind|branches]] and [[batchedleaf_generator#wind|leaves]]).  The recommended procedure is to run the Wind Wizard ("Tools->Wind wizard...") and then fine tune the results. Wind animation is controlled by editing the properties on the [[fanvfx|Fan object]] and the wind properties of each generator in the model (e.g., [[branch_generator#wind|branches]] and [[batchedleaf_generator#wind|leaves]]).  The recommended procedure is to run the Wind Wizard ("Tools->Wind wizard...") and then fine tune the results.
  
 When wind is enabled ('8' hotkey or "Enabled" property on the Fan) the model will animate continuously in the window (unless it's under timeline control as described below).  If the model is too complex to run fluidly, consider [[tooltree_window#Toolbar|focusing]] on a section to improve performance. When wind is enabled ('8' hotkey or "Enabled" property on the Fan) the model will animate continuously in the window (unless it's under timeline control as described below).  If the model is too complex to run fluidly, consider [[tooltree_window#Toolbar|focusing]] on a section to improve performance.
  
-===== Wind Strength and Direction =====+===== Wind strength and direction =====
 {{ ::wind_overlay.jpg?nolink|}}When wind is enabled an overlay appears under the Fan object in the upper right section of the window as pictured to the right.  Set the direction of the wind by rotating the Fan (hold 'G', press the left mouse button, and drag the cursor as a shortcut for fan rotation). {{ ::wind_overlay.jpg?nolink|}}When wind is enabled an overlay appears under the Fan object in the upper right section of the window as pictured to the right.  Set the direction of the wind by rotating the Fan (hold 'G', press the left mouse button, and drag the cursor as a shortcut for fan rotation).
  
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 The best way to get started tuning wind on a new model is to run the Wind Wizard ("Tools->Wind wizard...").  You will see the dialog pictured below. The best way to get started tuning wind on a new model is to run the Wind Wizard ("Tools->Wind wizard...").  You will see the dialog pictured below.
  
-{{ ::wind_wizard.jpg?nolink |}}+{{wind_wizard.jpg?nolink}}
  
 Answer the questions on the dialog and press "Ok".  SpeedTree will analyze your model and set wind properties on the generators and Fan object based on your model's structure and your wizard selections.  The model will recompute and wind will be enabled in the window when the wizard is finished.  Feel free to edit the results as described below. Answer the questions on the dialog and press "Ok".  SpeedTree will analyze your model and set wind properties on the generators and Fan object based on your model's structure and your wizard selections.  The model will recompute and wind will be enabled in the window when the wizard is finished.  Feel free to edit the results as described below.
  
-===== Editing Branch Wind =====+===== Editing branch wind =====
 Branch motion is controlled by five groups of properties: one for the motion shared by the entire model (like a tall pine rocking back and forth) and then four groups corresponding to each of the four discrete wind levels in the model.  Wind levels are determined by starting from the Tree generator and incrementing the wind level by one for every generator encountered on each path to the leaves that have wind enabled.  When you enable wind the Generation Editor displays the wind level on each generator where wind is enabled.  Consider the example below: Branch motion is controlled by five groups of properties: one for the motion shared by the entire model (like a tall pine rocking back and forth) and then four groups corresponding to each of the four discrete wind levels in the model.  Wind levels are determined by starting from the Tree generator and incrementing the wind level by one for every generator encountered on each path to the leaves that have wind enabled.  When you enable wind the Generation Editor displays the wind level on each generator where wind is enabled.  Consider the example below:
  
-{{ ::wind_levels.jpg?nolink |}}+{{wind_levels.jpg?nolink}}
  
 The "Trunk" has no number indicator because wind is not enabled on that generator (it usually isn't on trunks, "Shared" wind gets it).  Similarly, wind is not enabled for the "Roots" generator or its child labeled "Branch").  "Branch 1, 2, & 3" and "Twig 1, 2, & 3" all have wind enabled.  Notice how the wind level indicator starts at one, goes up to four, and then sticks at four for the last two twigs.  You can only have four discrete wind levels no matter how many generators have wind enabled.  It is okay to have fewer than four, and it is okay to have gaps in the number sequence as you see fit (sometimes it is better to concentrate the control near the trunk and twigs and leave middle sections alone). The "Trunk" has no number indicator because wind is not enabled on that generator (it usually isn't on trunks, "Shared" wind gets it).  Similarly, wind is not enabled for the "Roots" generator or its child labeled "Branch").  "Branch 1, 2, & 3" and "Twig 1, 2, & 3" all have wind enabled.  Notice how the wind level indicator starts at one, goes up to four, and then sticks at four for the last two twigs.  You can only have four discrete wind levels no matter how many generators have wind enabled.  It is okay to have fewer than four, and it is okay to have gaps in the number sequence as you see fit (sometimes it is better to concentrate the control near the trunk and twigs and leave middle sections alone).
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 The wind level indicator corresponds to the levels in the "[[fanvfx#VFX Branch Motion|VFX Branch Motion]]" group on the Fan.  Edit these properties to control the behavior of each wind level.  Edit the wind properties on each [[branch_generator#Wind|Branch]] generator to control weights and weight distribution along each branch. The wind level indicator corresponds to the levels in the "[[fanvfx#VFX Branch Motion|VFX Branch Motion]]" group on the Fan.  Edit these properties to control the behavior of each wind level.  Edit the wind properties on each [[branch_generator#Wind|Branch]] generator to control weights and weight distribution along each branch.
  
-When editing wind curves, the left-hand side of the curve corresponds to no wind ("Calm") and the right-hand side corresponds to maximum wind ("Stormy").  The black line indicates the current wind strength is pictured below:+When editing wind curves, the left-hand side of the curve corresponds to no wind ("Calm") and the right-hand side corresponds to the maximum wind ("Stormy").  The black line indicates the current wind strength is pictured below:
  
-{{ ::wind-curve.jpg?nolink |}}+{{wind-curve.jpg?nolink}}
  
 Use the curve to set low and high wind conditions and control how each level makes the transition.  Strength changes and gusts will cause the wind algorithm to look up this curve at various points to define the motion for a given simulation. Use the curve to set low and high wind conditions and control how each level makes the transition.  Strength changes and gusts will cause the wind algorithm to look up this curve at various points to define the motion for a given simulation.
  
-===== Editing Leaf Wind =====+===== Editing leaf wind =====
 Leaf wind animation is broken into two groups.  Assign a group and wind weight by editing the properties on [[batchedleaf_generator#Wind|Batched Leaf]] or [[leaf_mesh_generator#Wind|Leaf Mesh]] generators.  Typically, leaf group 1 corresponds to the leaves of the model while leaf group 2 corresponds to more rigid things like fruit. Leaf wind animation is broken into two groups.  Assign a group and wind weight by editing the properties on [[batchedleaf_generator#Wind|Batched Leaf]] or [[leaf_mesh_generator#Wind|Leaf Mesh]] generators.  Typically, leaf group 1 corresponds to the leaves of the model while leaf group 2 corresponds to more rigid things like fruit.
  
 Edit the properties in the "[[fanvfx#VFX Leaf Motion|VFX Leaf Motion]]" group to control leaf behavior. Edit the properties in the "[[fanvfx#VFX Leaf Motion|VFX Leaf Motion]]" group to control leaf behavior.
  
-===== Editing Frond Wind =====+===== Editing frond wind =====
 Frond wind is not broken into groups or levels.  All fronds share the same wind attributes.  Edit the properties in the "[[fanvfx#VFX Frond Motion|VFX Frond Motion]]" group to control frond behavior in general and edit the [[frond_generator#Wind|wind properties on each frond generator]] to fine-tune behavior. Frond wind is not broken into groups or levels.  All fronds share the same wind attributes.  Edit the properties in the "[[fanvfx#VFX Frond Motion|VFX Frond Motion]]" group to control frond behavior in general and edit the [[frond_generator#Wind|wind properties on each frond generator]] to fine-tune behavior.
  
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 You can force a gust to happen by double-clicking on the gust area of the wind overlay. You can force a gust to happen by double-clicking on the gust area of the wind overlay.
  
->**Note**:  “Duration” values of 0.0 still have an effect on gusting since the time to rise to the value and fall from it are not counted against the duration. Use 0.0 and low scalars to simulate turbulent conditions. +>**Note**:  “Duration” values of 0.0 still have an effect on gusting since the time to rise to the value and fall from it is not counted against the duration. Use 0.0 and low scalars to simulate turbulent conditions. 
  
 ===== Exporting ===== ===== Exporting =====
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 If you're exporting to Alembic you have the option to use the [[tooltimeline|Timeline Bar]] to control the wind.  Check the "Wind" box on the timeline and use the strength curve to explicitly control the wind strength.  This mechanism disables gusting and provides consistent, controllable wind strength on export. If you're exporting to Alembic you have the option to use the [[tooltimeline|Timeline Bar]] to control the wind.  Check the "Wind" box on the timeline and use the strength curve to explicitly control the wind strength.  This mechanism disables gusting and provides consistent, controllable wind strength on export.
  
->**Note**:  Wind animation does not loop.  You must export enough frames to cover your shot. +===== Best practices =====
- +
-===== Best Practices =====+
 The following list outlines a few things to keep in mind when tuning wind.  The following list outlines a few things to keep in mind when tuning wind. 
  
   * Always start with the Wind Wizard.  It should at least get you close.   * Always start with the Wind Wizard.  It should at least get you close.
   * Less is typically more - avoid large sweeping branch motions where possible, even in high wind conditions.  Medium "bending" and small "turbulences" typically work best.   * Less is typically more - avoid large sweeping branch motions where possible, even in high wind conditions.  Medium "bending" and small "turbulences" typically work best.
-  * Most frequencies should not be zero, even at calm wind conditions.  It's okay for motion to go to zero, but if anything moves on a tree it's usually moving quicker than you'd think!+  * Most frequencies should not be zero, even at calm wind conditions.  It's okay for the motion to go to zero, but if anything moves on a tree it's usually moving quicker than you'd think!
   * Make sure response times for multiple models are in agreement if they're going in the same scene.  Small, wispy models should have short response times while large models should have longer ones.   * Make sure response times for multiple models are in agreement if they're going in the same scene.  Small, wispy models should have short response times while large models should have longer ones.
   * Leaves usually start showing the effects of wind speed increases faster than branches.  Make sure your leaf curves reflect this with higher values on the left-hand side.   * Leaves usually start showing the effects of wind speed increases faster than branches.  Make sure your leaf curves reflect this with higher values on the left-hand side.