$treesway

Tree with treesway on de_lake in CS:GO (click to preview).

$treesway is a material shader parameter for the VertexLitGeneric shader available in all Source games since Left 4 Dead 2. (also in ) In , it can also be used for UnlitGeneric. $treesway morphs the vertices of a mesh with a given material around using the parameters of an env_wind entity to give the appearance of tree leaves and foilage blowing in the wind. The subparameters of $treesway determine how much the env_wind entity should affect the morphing, and all of them (except $treeswaystatic) must be specified in order for the effect to work properly. This shader parameter assumes any model using it is facing upwards.

Note:This shader parameter is disabled by default in the SDK. It can re-enabled by modding.

Warning:Due to the way bumped lighting is calculated, $treesway will not sway materials which use $bumpmap.

Bug:

• This shader parameter does not work with $detailtexturetransform.
• In , using a shadow-casting projected texture on materials with this parameter will cause flickering. As a workaround, try to keep trees away from where player flashlights can reach. $halflambert may also partially fix the issue.
• In , using a shadow-casting projected texture will cause shadows not reacting to $treesway, shadows don't move, expect in .

Todo: What about $singlepassflashlight and $flashlightnolambert?

  [todo tested in?]

Important:While $TreeSway can be used to animate a prop_static, lightmap shadows casted by swaying static props will remain static.
If CSM is unavailable, consider using a prop_dynamic instead. This can be combined with an animation containing more realistic pre-baked wind physics than can be achieved with $treesway.
As prop_dynamic cannot be lit by VRAD per-vertex, it may be desirable to use a pre-baked $lightmap (if available) in such situations, to restore some ambient lighting quality.

Parameters

$treesway <integer>

What option to use for the tree swaying effect.

• 0: No Sway
• 1: "Classic" tree sway.
• 2: Radial tree sway effect, intended for use on rectangular sheets of plastic/tarp attached at four corners. It inverts the sway scale radius to be 1 at (0,0,0) in model space and to fall off radially towards the edges of the model.
  Note:Models using $treesway 2 are expected to be built lying in the X Y plane in model space, with their center at the origin.

$treeswayheight <float>

The starting height in Hammer units where the effect should start being fully applied. Default 1000.

$treeswaystartheight <float>

The height from the model's origin in which the effect starts blending in. Default 0.2.

$treeswayradius <float>

The radius from the model's origin in Hammer units in where the effect should start being fully applied. Default 300.

$treeswaystartradius <float>

The radius from the model's origin in which the effect starts blending in. Default 0.1.

$treeswayspeed <float>

The speed multiplier of large movement such as the trunk. Default 1.

$treeswaystrength <float>

The distance multiplier of large movement such as the trunk. Default 10.

$treeswayscrumblespeed <float>

The falloff of the effect on large movement such as the trunk. Higher means a more stable center. Default 0.1.

$treeswayscrumblestrength <float>

The speed multiplier of the small movement such as the leaves. Default 0.1.

$treeswayscrumblefrequency <float>

The distance multiplier of the small movement such as the leaves. Default 0.1.

$treeswayfalloffexp <float>

The frequency of the rippling of a sine wave in small movement such as the leaves. Default 1.5.

$treeswayscrumblefalloffexp <float>

The falloff of the effect on small movement such as the leaves. Higher means a more stable center. Default 1.

$treeswayspeedhighwindmultipler <float>

Speed multiplier when env_wind triggers a gust. Default 2.

$treeswayspeedlerpstart <float>

Minimum wind speed in which a gust triggered by env_wind will start affecting the material. Default 3.

$treeswayspeedlerpend <float>

Minimum wind speed in which a gust triggered by env_wind will fully affect the material. Default 6.

$treeswaystatic <float> (only in )

Use a static wind value instead of the values from env_wind. If enabled, env_wind is not required.

$treeswaystaticvalues <vector2> (only in )

Sets the static wind values used by $treeswaystatic, syntax [x y]. Default [0.5 0.5].

External links

https://gamebanana.com/tuts/12924 - How to achieve a similar effect without $treeSway, on all source engine games. Alternatively, use an animated prop_dynamic, for a more realistic (but more expensive) effect.