View source for Unlocking chapters in your mod

[[Category:Level Design]] [[Category:Tutorials]] [[Category:Programming]]

=Valve Approach=
This approach shows the ''best'' way to update chapters in your mod.
== Renaming ==
Your maps should be renamed to conform to a pattern which allows you and the game to tell at a glance where a map is chronologically. 

Notice [[Half-Life 2|Half-Life 2's]] maps are named according to this pattern:
 "d#_areaname_##"
where 
* "#" represents the "day" of the game, is 1 for the beginning, 2 for the middle, and 3 for the endgame
* "##" is some numbered segment of an area "areaname"
 Example: d1_trainstation_01

However, [[Half-Life|Half-Life 1's]] pattern might make unlocking the chapters a little easier:
 "c#a$"
where
* # is the '''c'''hapter number
* $ is the '''a'''rea of the chapter with an extra letter appended as necessary.
 Examples: c1a4 c4a1b

== Updating ==
In <code>gameinterface.cpp</code>, modify <code>void UpdateChapterRestrictions( const char* mapname )</code> and the array <code>static TITLECOMMENT gTitleComments[]</code> to conform to your maps' naming format.

Each TITLECOMMENT in gTitleComments contains a <code>char* pBSPName</code> (the map name or part of a map name) and a <code>char* pTitleName</code> (the chapter that map or set of maps is part of). If you want the map e2m4 to be part of Chapter 2 of the mod Doom, add <code>{"e2m4", "#Doom_Chapter2_Title"}</code> to the array (with a trailing comma if it's not last, of course). Replace "e2m4" with simply "e2" and <i>all</i> maps starting with "e2" will be part of Chapter 2.

Note the comment right above gTitleComments, which reads "This list gets searched for the first partial match, so some are out of order". Meaning, if e2m9 is part of Chapter 3 and the rest of the "e2" maps are in Chapter 2,  then <code>{"e2m9", "#Doom_Chapter3_Title"}</code> must come <i>before</i> <code>{"e2", "#Doom_Chapter2_Title"}</code> in the array.

=== Necessary Fixes ===
UpdateChapterRestrictions has an inherent flaw which only comes to light when Steam runs a Source mod. Steam puts the mod's entire path in the command line; the mod MyMod might be run with <code>hl2.exe -game "C:\Steam\SteamApps\SourceMods\MyMod"</code>. 

But UpdateChapterRestrictions assumes "-game" to be just "mymod"(Mod name in lowercase), so <code>char chapterNumberPrefix[64]</code> ends up as <code>#C:\Steam\SteamApps\SourceMods\MyMod_chapter</code>, rather than <code>#mymod_chapter</code> as it should be.

You can solve this problem in one of two ways. The first and easiest is to dispense with the "-game" parameter and simply hardcode "#mymod_chapter" as the chapterNumberPrefix. The second, which may be copied and pasted across mods, is to lop off the parent folders one by one, perhaps with strtok, until only the mod folder is left.

=Map Hack Approach=
This tutorial will demonstrate unlocking chapters for your game mods using entities. If you are unfamiliar with adding chapters to your mod read and review the [[Adding chapters to your mod]] tutorial before this one.

== Create the [[trigger_once]] brush ==
Create a [[trigger_once]] brush in Map2. This will be used as the trigger that will begin the process of unlocking a chapter. Map2 is the map that will be considered the first map for the second chapter. Be sure to give the [[trigger_once]] brush a name, something like '''Trigger001_UnlockChapter2''' for example.

== Create the point entities ==
Use the entity tool the create a [[logic_relay]] entity. Set the name of the logic_relay entity to '''Logic001_UnlockChapter2'''. Set the logic_relay '''Start Disabled''' property to Yes.

Now use the entity tool to create a [[point_clientcommand]] entity, and set the name to '''UnlockChapter2'''.

== Add the outputs for the [[logic relay]] ==
Open the object properties dialog for the [[logic_relay]] entity we created earlier, and select the Outputs tab.
Now add two outputs using the add button and fill in the info as follows:
{| 
! My Output !!Target Entity!!Target Input!!Parameter!!Delay!!Only Once
|- 
| OnTrigger||UnlockChapter2||Command||incrementvar sv_unlockedchapters 2 100 -1||0.01||Yes
|- 
| OnTrigger||UnlockChapter2||Command||incrementvar sv_unlockedchapters 2 100 1 ||0.02||Yes 
|}

The '2' after the <code>incrementvar sv_unlockedchapters</code> is the chapter to make available. If you have more than 100 chapters in your mod (unlikely), make that value high enough to encompass them all.

===How it works===
The [[incrementvar]] command takes a minValue, a maxValue and a delta. Using a delta of <code>0</code> sets the sv_unlockedchapters to the maxValue which can be avoided by decrementing the var, then re-incrementing it, ensuring that the chapter to unlock is set, but not forcing it to that value if it is already higher.

== Add the outputs for the [[trigger_once]] brush entity ==
Next open the object properties dialog box for the [[trigger_once]] entity we created earlier called '''Trigger001_UnlockChapter2''', and select the Outputs tab. Now add a output using the add button and fill in the info as it appears in the picture below...<br>
[[Image:UnlockChapObjectProps2.png]]

== Testing ==
Now save, compile, and run. After your mod is loaded, type <code>showtriggers 1</code> in console. Once you have done so, play the map and walk through the [[trigger_once]] entity. After you have walked through it, press escape and select '''New Game''' from the game menu. You should see that chapter 2 in your mod has been unlocked. 

After you quit the game open up the <code>cfg/config.cfg</code> file in your mod and scroll down near the botton of the file. You will notice that the line that used to read <code>sv_unlockedchapters "1"</code> now reads <code>sv_unlockedchapters "2"</code>.