this is the file segment about rain spray and skid
// Gravel
[FEEDBACK]
Dry=0.75 Wet=0.60 Resistance=5000.00 BumpAmp=0.022 BumpWavelen=10.0 Legal=false Spring=0.0 Damper=0.0 CollFrict=0.8 Sparks=0 Scraping=0 Sink=0.017 Sound=gravel
Reaction=dust Tex=DustBrown.tga Max=128 Scale=(1.75,1.75,1.75) Growth=(2.0,2.0,2.0) ASDEnvelope=(2.0,0.2,3.5) DestBlend=InvSrcAlpha SrcBlend=SrcAlpha
Reaction=dirt Tex=Dustroad.tga Max=256 Scale=(2.5,2.5,1.0) Growth=(0.8,0.8,0.8) ASDDEnvelope=(2.0,2.0,1.0) TopSpeed=60.0 DistBetweenParticles=1.0 RampSpeed=50.0 OffsetVel=7.0 DestBlend=InvSrcAlpha SrcBlend=SrcAlpha
Reaction=softskid Tex=skidbrown.tga Max=1024 Pixel=NoReduceDetail Particle=Plane+Deformable+SingleSided DestBlend=InvSrcAlpha SrcBlend=SrcAlpha
Reaction=wetskid Tex=skidmud.tga Max=4096 Duration=10.0 Scale=(0.006,0.006,0.002) power=0.01 Pixel=NoReduceDetail Particle=Plane+Deformable+SingleSided DestBlend=SrcAlpha SrcBlend=SrcAlpha
Reaction=spray Tex=rainmud.tga Max=4096 Scale=(0.4,0.5,1.0) Growth=(1.6,0.1,5.0) GrowthVel=(0.1,0.065,1.30) Power=0.21 RampSpeed=40.0 OffsetVel=1.10 ASDEnvelope=(0.05,0.07,1.50) DestBlend=InvSrcAlpha SrcBlend=SrcAlpha
Materials=grvl