pg damage = 15, radius = 20

	points = damage * ( 1.0 - dist / radius );

points      dist      frames until landing
-------------------------------------------
0.696       19.072    10
1.9752      17.3664    9
3.2904      15.6128    8
4.6416      13.8112    7
6.0288      11.9616    6
7.452       10.064     5
8.9112      8.1184     4
10.4064     6.1248     3
11.9376     4.0832     2
13.5048     1.9936     1
(list of all dists less than 20 while coming down from a jump)


points is passed to G_Damage as damage


	knockback = damage;
	if ( knockback > 200 ) {
		knockback = 200;
	}

	...

	if ( !targ->client->ps.pm_time ) {
		int		t;

		t = knockback * 2;
		if ( t < 50 ) {
			t = 50;
		}
		if ( t > 200 ) {
			t = 200;
		}
		targ->client->ps.pm_time = t;
		targ->client->ps.pm_flags |= PMF_TIME_KNOCKBACK;
	}

all points values * 2 are less than 50 so t = 50
at 8 ms per frame, PMF_TIME_KNOCKBACK will be set for 6 frames

so in order for PMF_TIME_KNOCKBACK to still be set when PMF_TIME_LAND gets set
you need to land within 6 frames of getting pg knockback




the following notes don't change the fact that you have a 6 frame window

points is cast to an int when it is passed to G_Damage
dist is always an integer for two reasons:
    when a missile explodes its position is snapped (toward the direction it came from to make sure it doesn't end up outside the map)
  
    dist is calculated from a player's r.absmin/max, which is calculated in SV_LinkEntity from r.currentOrigin and r.mins/maxs
    r.mins/maxs are integral to begin with and r.currentOrigin is snapped after Pmove by BG_PlayerStateToEntityState
    additionally, r.absmins/max are padded by 1 unit