Here is an ffp shader (fixed-function pipeline shader, these work on virtualy any video car) for a realistic blood stain effect :

Here's the code

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material bloodeffect
{
effect="
technique burn
{
pass p0
{
AlphaBlendEnable=true;
//ColorOp[0.n] = Subtract;
srcblend=destcolor;
destblend=invsrcalpha;
}
}";
}

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