Overview

This tutorial will guide you through the creation and implementation of a mud 'splatter' Material Effect, which can be used with vehicles.

To do this we're going to create a new Particle Effect (or "PFX") and Surface Type as well as modify a vehicle script.

Particle Effect

First let's start with the Particle Effect as this will make up the bulk of our change. Start the Sandbox Editor with a new level open where we can create and test the effect.

Because this is a vehicle effect (although it doesn't have to be limited to that), the PFX will be created inside the existing "vehicles" PFX library.

To get started lets copy and modify the existing vehicles.Common.Ground.Light.Mud PFX and save it under vehicles.Common.Ground.New.NewMud. It now looks something like this:

It's a good idea to create your PFX against an easy-to-distinguish background, like a Designer object.

Material Effects

Okay, so we now have our new Particle but how exactly does the vehicle use it? Like most effects in-game, it runs through the Material Effects system.

Using Excel, open the file located in: <GameFolder>\Libs\MaterialEffects\MaterialEffects.xml

If you scroll down a bit you will find the following block of information:

Disregard the inclusion of the "SCAR" row for this tutorial.

Those of you familiar with the SDK will probably recognize some familiar sounding vehicles listed here. In this case we're going to be working closely with the HMMWV content.

Shortly we'll explain how exactly these setups all communicate, but for now, create a new row underneath (doesn't technically matter where) the vfx_HMMWV and call it "vfx_CarNew".

Also add a new column called mat_mud (typically you would arrange these better, in groups).

So, three new main pieces of content we've added here are:

• A new surface type reference called "mat_mud".
• A new mfx row called "vfx_CarNew".
• A new reference to the vehicles FXLib with "new_mud".

Surface Types

As mentioned just above, we've created a new reference to a new surface type, but that surface type does not yet exist, you cannot assign it to any materials yet.

To create a new surface type simply open the file: <GameFolder>\Libs\MaterialEffects\SurfaceTypes.xml

Add in a new entry as follows (copied mat_soil but lowered the friction value to better simulate mud):

 <SurfaceType name="mat_mud">
  <Physics friction="0.15" elasticity="0" pierceability="7" can_shatter="1" sound_obstruction="0.5" />
 </SurfaceType>

Now you can assign the "Mud" surface type in your material that you're going to be driving on.

FXLibs

Now we have our SurfaceType setup and our terrain material is using it. We also have our MaterialEffect setup but what was that "vehicles:new_mud" entry we made all about anyway? That was our FXLibs entry!

Open the following file: <GameFolder>\Libs\MaterialEffects\FXLibs\vehicles.xml

In here you'll find some familiar sounding entries that you may have noticed in the MaterialEffects spreadsheet. It's currently split into 3 sections: Heavy, Light and Helicopter.

We're going to make a new section, based off the last entry in the "Light" section:

    <Effect name="new_mud">
        <Particle>
            <Name>vehicles.Common.Ground.New.NewMud</Name>
        </Particle>
        <Sound>
            <Name>soil</Name>
        </Sound>
    </Effect>

Here we reference the Particle Effect we want to use as well as the Sound it should use (we'll use the existing "Soil" entry as it's close enough).

Vehicle Script

At this point we've got one final thing to do, and that's figure out what to do with the "vfx_CarNew" entry we created earlier.

Open up the HMMWV vehicle script here: <GameFolder>\Scripts\Entities\Vehicles\Implementations\Xml\HMMWV.xml

Scroll down towards the bottom and you'll see a "Particles" block which looks something like this:

Now lets modify the HMMWV script to see if our setup works. Change the mfxRow parameter to use our new "vfx_CarNew" row.

If you haven't already, now would be a good time to restart the Editor to bring in all of our changes.

Testing

New Mud Effect	No Grass Setup for the vfx_NewCar row!
Testing New Surface Types	Particle System only bound by your creativity!