function trace_wing2_alpha(PARTICLE *p)
{
p.alpha -= 0.1*time_step;
p.size -=0.1*time_step;
if (p.alpha <= 0) p.lifespan = 0;
}
function trace_wing2(PARTICLE *p)
{
set(p, BRIGHT|TRANSLUCENT|BEAM);
p.alpha = 1;
p.size = 3;
p.event = trace_wing2_alpha;
}
action fly(){
while(1){
vec_for_vertex(wing_trace2.x,me,2258);
vec_set(last_pos_wing2.x,wing_trace2.x);
here is forward movement code using physics parameters...
phent_addforcelocal (my, vector(200,0,0),nullvector);
effect(trace_wing2,10,wing_trace2.x,vec_sub(last_pos_wing2.x,wing_trace2.x));
wait(1);}
}