/**
* Copyright (c) 2005-2017, KoLmafia development team
* http://kolmafia.sourceforge.net/
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* [1] Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* [2] Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* [3] Neither the name "KoLmafia" nor the names of its contributors may
* be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
package net.sourceforge.kolmafia.combat;
public class CombatUtilities
{
public static final float hitChance( final int attack, final int defense, final float critical, final float fumble )
{
// The +d10-d10 in the Hit Chance formula means the distribution is not linear.
//
// According to the Wiki
// http://kol.coldfront.net/thekolwiki/index.php/Monsters#Monster_Hit_Chance
// it is the Cumulative Distribution Function of a triangular distribution
// https://en.wikipedia.org/wiki/Triangular_distribution
// a = -9, b = 10, c = 0.5, x = defense - attack
float missChance = CombatUtilities.triangularDistributionCDF( -9.0f, 10.0f, 0.5f, defense - attack);
return Math.min( 1.0f - missChance + critical, 1.0f - fumble );
}
public static final float triangularDistributionCDF( final float a, final float b, final float c, final float x )
{
/*
(defun cdf (a b c x)
(cond ((<= x a)
0)
((<= b x)
1)
((<= x c)
(/ (* (- x a) (- x a)) (* (- b a) (- c a))))
(t
(- 1 (/ (* (- b x) (- b x)) (* (- b a) (- b c)))))))
*/
return x <= a ? 0.0f :
b <= x ? 1.0f :
x <= c ? ( ( x - a) * ( x - a) ) / ( ( b - a) * ( c - a ) ) :
( 1.0f - ( ( b - x) * ( b - x) ) / ( ( b - a) * ( b - c ) ) );
}
}