Meditation may use wrong formula

[GriffonSpade]

Meditation in the scripts uses this chance to successfully activate:

double chance = (50.0 + ((skillVal - (m.ManaMax - m.Mana)) * 2)) / 100;

This appears to be the pre-Publish-46 formula originally intended for players whose max mana was only 100. A player with 100 meditation and 0/125 mana would be unable to activate meditation, and one with 25/125 would have a 50% chance.

It seems likely it was moved to a percentage-based formula as such:

double chance = (50.0 + ((skillVal - ((m.ManaMax - m.Mana) * 100 / m.ManaMax) * 2)) / 100;

This would normalize everyone to have the same chances to meditate as a player with the same percentage as a 100 mana player has right now. (And it gets very silly if used by things with hundreds of mana who wind up with negative hundreds of percent chance to meditate at low mana)

Further, it may only be used with those who have over 100 mana, while those with less still use the old formula.

However, it needs some testing on live OSI to confirm, as repo only contains files going back to 2013. If the latter version is correct:

50% to meditate at 100 meditation, 0/125 mana
100% to meditate at 100 meditation, 32/125 mana (25% mana)
0% to meditate at 0 meditation, 75/100 or 94/125 mana (75% mana)
0% to meditate at 75 meditation, 0/125 mana
50% to meditate at 50 meditation, 63/125 mana (50% mana)
100% to meditate at 75 meditation, 63/125 mana (50% mana)

For checking sub-100 mana two likely possibilities:

Still uses old formula:
100% to meditate at 50 meditation, 0/25 man
50% to meditate at 25 meditation, 0/25 mana
50% to meditate at 0 meditation, 24/25 mana (99% mana)
0% to meditate at 0 meditation, 0/25 mana

Uses percentage formula:
50% to meditate at 100 meditation, 0/25 mana
100% to meditate at 100 meditation, 7/25 mana (25% mana)
50% to meditate at 0 meditation, 13/25 mana (50% mana)
0% to meditate at 75 meditation, 0/25 mana
0% to meditate at 50 meditation, 12/25 mana (50% mana)
0% to meditate at 25 meditation, 6/25 mana (25% mana)
0% to meditate at 0 meditation, 18/25 mana (75% mana)

 

[Dexter_Lexia]

I'm having trouble finding any forumla for meditation chance. All I can find is mana regen rates formulas.

 

[GriffonSpade]

Yeah, it took me something like a half-hour to an hour to dig anything up on it.

I found some mention on a forum from before build 46, 1 July 2007, which lined up quite well with what we have right now.

The Anti-Adam:
General rule - Don't attempt to Meditate if your Mana pool - Current Mana >= Meditation skill - 10.

Examples

40/120 Mana with 100 Meditation = Very good chance to meditate (probably will never fail)
30/120 Mana with 100 Meditation = Good chance to meditate (70-80%)
20/120 Mana with 100 Meditation = Moderate chance to meditate (40-60%)
0/120 Mana with 100 Meditaiton = VERY Small chance to meditate (5-10%)

Disclaimer: All numbers are made up/estimates off of my own observations.

Baldguy:
there is a purported fix by leurocian, but it has not made it into the publish schedule yet. The problem actually came about once we could take our int over 100.

Then, publish 46 in 10 August 2007:

• Having higher Meditation and / or Focus skill will give a bonus to mana regeneration gained from MR items.
• Meditation and /or Focus will now benefit for intermediate values and not just for multiples of 10 (i.e. 80.1 used to give you same MR bonus at 89.9).
• Players now have a better chance of actively meditating at high intelligence/low mana values.
• Fractional values of meditation will now count towards mana regen

Also, to make it not change for those at/under 100 mana, use these lines in meditation.cs line 79:

  double chance = m.ManaMax <= 100 ?
  (50.0 + ((skillVal - (m.ManaMax - m.Mana) * 2))) / 100 :
  (50.0 + ((skillVal - ((m.ManaMax - m.Mana) * 100 / m.ManaMax) * 2))) / 100;

 

[ppardalj]

At UO Legends we used to have:

double chance = ( 75.0 + ( ( skillVal - ( m.ManaMax - m.Mana ) ) * 2 ) ) / 100;

and it felt pretty accurate...

 

[GriffonSpade]

Eh, it would probably be pretty close for those with high int, but because that would be a flat 25% chance increase, it would also give low-int meditable builds the same improved chance. Improving chances for high int/low mana seems like the best way to do it is to use a percentage at over 100 int (max mana) values.