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<section id="sbalistique" revision="$Revision: 1841 $ $Name$"
  vendor="1.12" xmlns:xi="http://www.w3.org/2003/XInclude">
  <title id="stbalistique">Balistic Shot</title>

  <para>Balistic shooting correspond to throwing a projectile in a
    curve so that it fall on the target.  This shot aren't one of
    precision but of distance instead and the important is often not
    the target itself but where the projectile fall
    effectively.</para>
  
  <para>Balistic shots are based on the result of a manipulation roll
    of the weapon used (which can be a simple Throw roll for example)
    after you have evaluate both the distance and direction that you
    want to reach.  The roll give you some degrees of success (DS)
    which will be used to determine the point of impact of the
    projectile, from the target.  The consequence are then determined
    from the type of projectile used and the place reach by it.</para>

  <variablelist>
  <varlistentry>
    <term>Vertical Error (E&b;)</term>
      <listitem>
        <para>The vertical error determine the distance by which the
          projectile miss the target.  This error is equal to E&b; =
          2×D - <link linkend="tpb">P&b;</link> - DS, where the Value
          of D is taken with the same units as P&b;.  This Value is
          converted in Measure and represent the distance between the
          target and the effective impact position, in the direction
          of the shooter.  So, it can be greater than the distance
          between this one and the target.</para>

        <note userlevel="adv">
          <para>A consequence of this rule is that the average maximum
            aim distance is equal to D = P&b; + DS.  The average
            maximum reach is equal to the quarter of this, which is
            P&b; + DS - 6.</para>
        </note>
      </listitem>
    </varlistentry>
    <varlistentry>
      <term>Lateral Error (l)</term>
      <listitem>
        <para>The lateral error determine of how much the shot has
          deviated and on which side.  You must first roll ±d10.  The
          sign of the roll indicate the direction.  If the result is
          negative, the shot will go on the left-hand side of the
          shooter.  If the sign is positive, the shot will go on the
          right-hand side.  If the result is 0 (for example 3-3, or
          6-6) and both number are odds, the shot will go on the left.
          Elsewhere, it will go on the right (the dice can't be
          different, since this will mean that the result is not
          zero).  The lateral distance is equal to the Measure of E&b;
          - <link linkend="tlb">L&b;</link>, sum up with the absolute
          value of the precedent roll.  For this, the maximum E&b; is
          equal to P&b;+Level-3, to avoid that the projectile goes too
          far.</para>

      </listitem>
    </varlistentry>    
  </variablelist>

  <section id="sbalconseil">
    <title id="stbalconseil">Conseil d'utilisation</title>

    <para>This method can be a bit unconfortable for the players if it
      is apply mecanically.  Normally, the characters have only an
      approximate idea of the target distance and the one they are
      able to reach.  So, they should make a roll to evaluate this
      distance approximately.  If the roll is a success, when the
      target is near (with 2×D approximately lesser or equal to P&b;),
      the player should try it's luck and aim directly the target, the
      shot having good chance to hit it.  If the distance is greater,
      she should try slightly behind the target to get an advantage
      from the error to reach the target.  For sure, more the
      character is good, less it should go far behind (in fact, simply
      add the level of the character to the weapon P&b; to evaluate
      the effective precision of the character).  Depending on the
      roll results and the distance from the impact point, the
      character will choose if he want to throw it a little farther or
      a little nearer the next shot.  So, add or remove a short
      distance according to the will of player description of the
      action, and try to take it into account in the next roll,
      without never communicate the exact distance to the player.  And
      remember about the optical illusions that the landscape can
      create on the distance!</para>
    
    <note userlevel="adv">
      <para>This rule are part of those rules that I hate much: the
        ones where the success margin must be interpreted in a
        quantitative manner (it's also the case of the damage).  As
        said in <xref linkend="smarge"/>, the degrees of success
        shouldn't modify the action itself but its quality only (less
        or more well execute, badly or atrociously failed).  The
        problem here is that I doesn't really have the choice to not
        take the DS into account in a quantitative way since the
        result of an error can be very important and couldn't be
        without consequence!</para>
    </note>

    <note userlevel="adv">
      <para>For the curious, the difficulty of the roll here is the
        distance.  That's why this one shouldn't be taken into account
        when rolling for the DS.  The roll could have a difficulty of
        -D, and the error equation would then be E = D - P&b; - DS.
        However, since the difficulty affects directly DS, we have DS
        = DS' - D and so, E = D - P&b; - ( MR' - D ) = 2×D - P&b; -
        DS'.  C.Q.F.D.  This error equation so it's really a
        quantification of the failure margin for a choose difficulty
        (the distance).</para>

      <para>I had a method that let me have a null error for a
        positive roll, but it make the calculation complicate and
        doesn't give anything more (we simply adjust the precision
        factor in consequence).  This method is simpler and
        quicker.</para>
    </note>
  </section>
</section>
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