$treesway
de_lake in CS:GO (click to preview).$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, except in and Games now running on the 'TF2 SDK' ( 2025 Version of SDK2013MP ). [todo tested in ?]
Note:There was a TODO here, asking about the impact of $singlepassflashlight and $flashlightnolambert on this.its important to clarify this to avoid further confusion:
These are Parameteres that affect the rendered Material only.
For creating the 'Shadow Map' ( Depth Texture, Projected Texture, etc ), an entirely separate Shader is used.
That Shader (DepthWrite) did not have the $TreeSway Code, causing Shadows to be entirely unaffected by this feature.
It can't 'simply' be added either, only some Parameters from the original Material are copied to it.
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
$treeswayheight
$treeswaystartheight
$treeswayradius
$treeswaystartradius
$treeswayspeed
$treeswaystrength
$treeswayscrumblespeed
$treeswayscrumblestrength
$treeswayscrumblefrequency
$treeswayfalloffexp
$treeswayscrumblefalloffexp
$treeswayspeedhighwindmultipler
$treeswayspeedlerpstart
$treeswayspeedlerpend
$treeswaystatic
$treeswaystaticvalues
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.