Clutter Effect Layer
The Clutter Effect Layer is an Effect Layer type which is used to render small localised ground clutter (small foliage, stones, etc.) As with all effect layers, clutter is painted onto the terrain and automatically generates appropriate geometry for the area surrounding the camera.
Using the Clutter Effect Layer In-Game
For specific guidance how to create and paint clutter layers in Surveyor see: Help:Effect_Layer_Dialog
Before you start looking at creating assets for Clutter Effect Layers you should have a very good knowledge on how you go about modelling efficient meshes for each LOD level and what textures you should be using for each mesh LOD. You can find an excellent reference on how to model and texture assets under the Modelling Overview on the Art Recommendations Trainz wiki page.
When using a large amount of clutter objects onscreen at one time, it's best to have at least the lowest LODs (which shouldn't be very far from the camera) using a Texture Atlas. The texture atlas should be as small as it can be while maintaining good visual results (256x256 perhaps) and will hold all the images for all the assets lowest LODs. This means when the lowest LODs are showing (which should be the majority of clutter onscreen most of the time) you'll only be paying the cost of 1 material shared across all the lowest LODs.
You will also want to share as many single textures between as many assets as possible to cut-down on draw calls where possible - If you have 3 ferns all of different sizes, don't make 3 copies of the same texture.
You will want to make sure you understand how to create a Trainz Mesh Library asset so you can utilise Texture Atlases and sharing of textures between multiple meshes.
Once you start to construct your Trainz mesh library asset be sure to use the m.clutter material for all your meshes. This will allow your clutter asset to fade in and out where required. You will also want to take note about the fadeInEndDistance and fadeOutEndDistance in your mesh metadata files to get your fade transitions correct.
Clutter Asset Selection
There are several factors to consider when determining which assets you should put in a clutter layer:
1. How big is the asset? Anything that has a size of ~1 meter cubed or smaller can be considered as clutter. This is not to say it must be clutter but anything larger than that you should place with the Objects tab.
2. To get the nice fade-out transition (and fade-in if you've configured that) your clutter asset should use the material m.clutter.
3. LODs are a MUST! If your asset has no LOD or poor LOD don't even consider using it for clutter as it will be very performance heavy.
You can find all the information on creating clutter assets under m.clutter.
It is strongly recommended that assets created for use in a clutter effect layer are small, relatively low polygon (100-500 polygons at highest LOD), with very efficient LOD (typically down to 5-10 polygons at lowest LOD) and using the m.clutter material type. It is possible to create very attractive and high-density scenery with well-built clutter assets. However inefficient asset creation can very quickly lead to very poor performance.
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