[CF-Devel] skill doc.
crossfire-devel-admin at archives.real-time.com
crossfire-devel-admin at archives.real-time.com
Sat Apr 5 01:41:58 CST 2003
Started working on the new skill system. I decided to update the
documentation first to get an idea of where to go to/what to write. I figured I
might as well put it out to the list and see any comments or other notes people
might have.
SKILLS/EXPERIENCE DOCUMENTATION for DEVELOPERS
----------------------------------------------
- Summary -
0. Introduction
1. Sketch of system
a. Initialization - how skills and experience are linked
2. How to add new skills
a. creation of new skill: outline of needed steps
3. Detail of skill archetype values.
4. Skill Tools
5. Skill Scrolls
6. Workings of the Skill System
-------------------------------------------------------------------------
0. Introduction
---------------
Skills were redone to a large extent in April 2003. This document has been
updated to reflect how the skills work.
The main change is that experience categories were removed from the game.
Instead, experience goes to the skill itself. Thus. how good a player is at
the skills is directly proportional to how good they are at that skill, and
not the category itself.
1. Sketch of system
-------------------
In the skills/experience code, players gain experience for the activities
which they perform in the game ("You are what you do"). The activities a
player may engage in are controlled by the skills they possess. All players
start with a basic set of skills which they may expand through adventuring.
While monsters do not gain experience from the use of skills, they may use any
skills which exist in their inventory if they have the can_use_skill flag set.
In the code, skills are objects which exist in the player/monster inventory.
Both NPC/monsters and players use the same skill archetypes. Not all skills
are however enabled for monster use. Check the Skills_players.doc for
available NPC skills.
The experience one gets for a skill is greatly simplified. No longer
is it weighted based on the stats of the player. Rather, the experience is
based on what the skill was used for - opening a tough trap gets more
exp than opening an easy trap. The stats the player has will improve
the chances of success in most cases - this is bonus enough without also
gaining additional experience.
The chracters total experience is no longer related to the sum of experience
in the players skills - A player could for example only of 1000 exp, but have
skills with 2500 exp, 300 exp, etc. Removing the tie between skills and total
experience allows for reasonable skill advancement - you can allow a player
to easily get to level 20 in a skill without them now being level 20 player.
Note also that the only tunables are now in the code or in the archetypes -
if the exp for disarming is out of whack, the code would need to be changed
to give more appropriate amounts.
2. How to add new skills
-------------------------
Adding a new skill to CF is not overly difficult, it is little more difficult
than adding new archetypes and a spell to the game.
a. creation of new skill: outline of needed steps
A number of steps are required to create a new skill.
1) Edit a new skills archetype. See below for appropriate parameters. If
you desire the skill to be a skill tool, edit a "face" for the new skill.
If you want to have the skill to be learned via a skill scroll, edit a
skillscroll for the skill. Place the new archetype(s) in the
lib/arch/skills directory. Remember to name your new skill appropriately
(ie skill_<new skill name>). Make sure you select a unique subtype
for your new skill.
2) Edit skill_util.c. Add an entry for the skill in do_skill() (so that it may
be used as a "long-range attack"). If the new skill is a hth attack take a
look at the attack_hth_skills[] table in do_skill_attack() -- where does
the hth attack rank? The most useful attacks should occur earlier in the
table.
3) Create the skill code. If you created a hth attack, you probably can get
away with just using attack_hth. For other skills, put the skill code in
skills.c. If your new skill is to be an "associated" skill, then make sure
that it returns the value of calc_skill_exp().
4) Edit treasures/artifacts file as needed (esp. if your skill will become one
of the starting skills, or will show up in shops.)
3. Detail of skill archetype values.
------------------------------------
This section details the various object/archetype values.
First, we detail skill objects:
type: SKILL
subtype: subtype of skill
invisible: 1
no_drop: 1
name: Name of the skill, used by things like 'use_skill', as well as output
of 'skills' command.
stats (Str, Dex, sp, grace, etc): These modify the abilities of the player,
in a sense giving bonuses.
expmul: this is the ratio of experience the players total should increase by
when this skill is use. If this is zero, then experience only goes to
to the skill. Values higher than 1 are allowed. Note that experience
rewarded to the players total is in addition to that given to the
skill. Eg, if player should get 500 exp for using a skill, and
expmul is 1, the player will get 500 added to that skill as well as
500 to their total.
exp: The exp the player has in the skill.
level: The level of this skill
can_use_skill (flag): If this is set, the player knows the skill natively
(eg, does not need a skill tool, see below). If this is not set,
then this skill object is acting as a container for experience.
For example, if a player is using a holy symbol in order to get his
praying skill, we still need to have skill_praying in the players
inventory to store the experience in. However, the player can't
use that praying skill without a holy symbole until they learn it from a
skill scroll.
4. Skill Tools
-----------------
Skill tools are items that let a player use a skill they do not otherwise
know. Skill tools may also have advantages, eg, spellpaths they grant to the
caster, stat bonuses, etc.
Most of the values for the skill tools are just like normal equipment
(value, weight, face, body_..., ) fields.
type: skill_tool
skill: Name of the skill this object allows the user of.
5. Skill Scrolls
----------------
type: SKILLSCROLL
skill: Name of the skill to be learned
Rest of the values are per normal equipment (weight, value, identified,
etc).
6. Workings of the Skill System
-------------------------------
This section attempts to briefly explain how this all works.
Due to the addition of the skill pointer, it is no longer required
that a skill be in the ready_skill position to gain experience.
Whenever a player tries to use skill either directly (ready_skill ..)
or indirectly (cast a spell which requires knowledge of the skill), the
code will examine the players inventory to see if they an in fact
use the skill. This first checks to see if the player has the appropriate
skill archetype in their object. If they do, and can_use_skill is set
to 1, nothing more is done. If that is not the case, we then look for
a skill tool. If none is found, we tell the player the can't use the
skill. If one is found, we try to apply the skill tool - if this can not
be done, we also error out.
Only if the player explicitly activates a skill with ready_skill do
we change the players range pointer. Otherwise, it will remain as is
(but not that casting a spell might also change the range pointer).
add_exp has been modified to take two additional parameters -
skill_name and flag.
skill_name is the skill to add the experience to. By passing this
to add exp, a lot of the code no longer needs to change chosen_skill,
then reset it back again.
flag determines what to do if the player does not currently have the
skill pointer in their inventory. This can arise if the player
is using a skill tool, or part of a party.
In the default case of flag being 0, if the player does not currently
have the skill in their inventory, this is added (with can_use_skill 0).
If flag is 1, we add the exp to the players total exp, but don't
give them any in the skill. If it is 2, the player gets nothing.
This fixes many of the abuses of party combat - if a member of your
party is killing things with wizardry, you'll get wizardry exp. If
you don't have wizardry, you'll get some general exp, but you can't
funnel it into things like alchemy anymore.
The effect of flag 1 to add exp is so that that a player can't have
thousands of exp in a skill and never have used in themselves - for a player
to have any exp in a skill, he will have had to use it at least once. Note
however that a player could have used the skill just once (to say kill a
kobold) and yet get a bunch more exp from party members that are actually good
wizards.
The handling of add_exp with skill_name is pretty simple. In most cases, we
know immediately the skill that was used (eg, melee combat, search, disarm,
etc). In cases of indirect death (spells), we set the skill in the spell
object to the skill that it should get awarded to.
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