Introduction to Half Life 2 Modding

1
Introduction to Half Life 2 Modding

• Seminar Seven
• The story so far
• Creating a mod via Source SDK
• Introduction to Hammer
• Hammer techniques
• Importing custom art content
• This week
• Mod organisation and starting to code
• Homework
• See how much you can break the code

2
Mod Layout

• Folder structure
• Bin contains all DLL files
• Cfg contains all configuration files
• Maps all files relating to maps (BSP, sound
  caches, nav graphs)
• Materials all texture / material files (VMT /
  VTF)
• Media video to play at game startup
• Models all model files (MDL, PHY, VVD and VTX)
• Resource files that dictate visual appearance
  (HUD, menus).
• Scripts files that control everything else
  (weapons, audio effects etc)
• Shaders compiled shader files (VCS) both
  pixel and vertex
• Sound all sound files (MP3 / WAV)

3
Altering the visual style

• ClientScheme.res
• Controls menu styles
• Font type, size and colour
• Setting background image
• Insert VTF/VMT into materials/console
• The VMT shader is UnlitGeneric
• Create / modify scripts/ChapterBackgrounds.txt
• Enter name of VMT file, minus extension and
  location.
• Altering the HUD
• Core file is scripts/HudLayout.res

4
Overview of code

• The code base is divided into two sections
• Client and Server
• Client controls rendering and visual effects
• Server controls game logic (it does the
  'thinking')
• There is communication between the two sections
  and some bits of code appear in both!
• The code base is not a simple beast!
• Over a million lines of code, only 15 of which
  are comments!
• The Hidden has added 20,000 lines of new code
  and it's still not done!

5
Working with the code

• The current code base can be opened in either
  Visual Studio 2003 or 2005.
• It's currently easier to work in 2005!
• It contains two projects, client_sdk and hl
• client_sdk is all client code
• hl is all server code
• Some code is found in both projects
• Open weapon_rpg.cpp find it in HL2MP / weapons
  on the sidebar.
• Note the series of statements such asifdef
  CLIENT_DLL.

6
Modifying the code

• With weapon_rpg.cpp still open
• Find the line that reads define RPG_SPEED 1500
• Modify the value to something significantly
  different
• 500 or 2500 would be good!
• Compile (Ctrl-Shift-B or Build Build Solution)
• This will take some time the first time you do
  it!
• You have now successfully created a modification
  for HL2 simple as it may be!

7
Adding code

• Now we'll look at adding an item to the code
• We'll copy an existing weapon
• This requires new code and new items in the mod
  folder
• Open weapon_smg1.cpp
• Note there is no matching header file (this makes
  our life a bit easier)
• Select all the code and copy it (Ctrl-A then
  Ctrl-C)
• Add a new folder to the client project
• Right Click 'client' Add New Folder
• Add a new item to that folder
• Right Click folder Add Add New Item
• Select C file, enter a file name
  (weapon_.cpp), create a new folder under
  game_shared use that as the save location

8
Adding code (cont.)

• In the empty window, paste the code we just
  copied
• Now we need to rename the class find a bit of
  code that says the class name (CweaponSMG1)
• Copy the WeaponSMG1 part (not the C!)
• Use Find and Replace (Ctrl-H)
• Enter WeaponSMG1 as the Find and WeaponSMGMine as
  the Replace press Replace All.
• Final stage in code add the new file to the
  server project!

9
Adding code (cont.)

• Add a new folder to the 'hl' project
• Rather than adding a new item, add an existing
  one and find the weapon_smg2.cpp file we just
  created.
• See now why we put the file in game_shared?
• One last change in code line 85
  (LINK_ENTITY_TO_CLASS) and 86, change weapon_smg1
  to weapon_smg2
• This tells the game where to look for the script
  information and stops it getting confused

10
Finishing off the weapon

• Find weapon_smg1.txt in the mod scripts folder
• Copy and paste it
• Rename it to weapon_smg2.txt
• Open weapon_smg2.txt
• Change bucket_position to 2
• Play with the values (alter the clip_size, change
  the view model etc)
• Boot up the game and see your changes
• Use give weapon_smg2 to play with your new
  weapon.