// gStart, gEnd here are grenade trajectory points

for (t = 0.0; t <= dtime; t += dt)
{

    gEnd[0] = gStart[0] + GrenadeVelocity[0] * dt;
    gEnd[1] = gStart[1] + GrenadeVelocity[1] * dt;

    new Float:gForce = 0.4 * float(gravity.IntValue);
    new Float:NewVelocity = GrenadeVelocity[2] - gForce * dt;
    new Float:AvgVelocity = (GrenadeVelocity[2] + NewVelocity) / 2.0;

    gEnd[2] = gStart[2] + AvgVelocity * dt;
    GrenadeVelocity[2] = NewVelocity;

    new Float:mins[3] = {-2.0, -2.0, -2.0}, Float:maxs[3] = {2.0, 2.0, 2.0};

    new Handle:gRayTrace = TR_TraceHullEx(gStart, gEnd, mins, maxs, MASK_SHOT_HULL);

    if (TR_GetFraction(gRayTrace) != 1.0)
    {
        if (TR_GetEntityIndex(gRayTrace) == client && t == 0.0)
        {
            CloseHandle(gRayTrace);
            gStart = gEnd;
            continue;
        }

        TR_GetEndPosition(gEnd, gRayTrace);

        new Float:NVector[3];
        TR_GetPlaneNormal(gRayTrace, NVector);
        new Float:Impulse = 2.0 * GetVectorDotProduct(NVector, GrenadeVelocity);
        for (new i = 0; i < 3; i++)
        {
            GrenadeVelocity[i] -= Impulse * NVector[i];

            if (FloatAbs(GrenadeVelocity[i]) < 0.1)
                GrenadeVelocity[i] = 0.0;
        }

        new Float:SurfaceElasticity = GetEntPropFloat(TR_GetEntityIndex(gRayTrace), Prop_Send, "m_flElasticity");
        new Float:elasticity = 0.45 * SurfaceElasticity;

        ScaleVector(GrenadeVelocity, elasticity);

        new Float:ZVector[3] = { 0.0, 0.0, 1.0 };

        if(GetVectorDotProduct(NVector, ZVector) > 0.7) // old value from CS:Source

        {
            if (StrEqual(cWeapon, "weapon_incgrenade", false) || StrEqual(cWeapon, "weapon_molotov", false))
                dtime = 0.0;
        }
    }
    CloseHandle(gRayTrace);

    new Float:width = GetConVarFloat(sm_gtrajectory_size);
    TE_SetupBeamPoints(gStart, gEnd, _Laser, 0, 0, 0, trajectory_show_time, width, width, 0, 0.0, trailcolor, 0);
    TE_SendToAll(0.0);

    gStart = gEnd;
}