float v1 = length(vector(point(1, "v", @ptnum)));
float v2 = length(vector(point(0, "v", @ptnum)));
if( v2-v1 > 0.5){
    //@Cd = set(1,0,0);
    f@emitparticles = 100000.0;

}else{
    f@emitparticles = 0.0;
    removepoint(0,@ptnum);
}

float maxVal = max(abs(@v.x), max(abs(@v.y), abs(@v.z)));

if( maxVal == abs(@v.x) ){
    @v = set(@v.x,0,0);
}else if(maxVal == abs(@v.y)){
    @v = set(0,@v.y,0);
}else if(maxVal == abs(@v.z)){
    @v = set(0,0,@v.z);
}