Oddworld : Stranger

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Oddworld Strangers Wrath
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The good news
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The bad news - youre not Valve or Bungie

• Most of your team are weak links
• Design is unclear and changes often
• Have to make demos with little notice
• Features get cut and added at all times
• Content team and other coders dont follow the
  rules

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(No Transcript)
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The Oddworld Method

• Lead Programmers make the whole company more
  productive
• Use the code and engine to help other coders,
  content developers
• Improve your weak points, dont perfect your
  strong points each company is unique
• Rapid development and messy design iteration,
  ease of changes, forgiving design tools

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The Oddworld Method, cont.

• robustness, flexibility, and rapid-response
• the engine is at all times crash-free and can be
  turned into a shippable demo on short notice
• little tips to improve productivity are worth
  millions
• many of your coders are junior make it hard for
  juniors to write broken code eg. Code that
  seniors write should be self-correcting
  self-enforcing

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Never bring down other people

• People make mistakes, you cant stop that
• Make mistakes only affect that one system
• Everything is in perforce roll back bad content,
  bad builds
• All code is reviewed
• Compiler asserts table size checks
• Exceptions

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Background engine summary

• All tools in Maya, all geometry triangle soup
• Visibility through portals, clip frustum, scissor
• Zones also define paging units and ticking
  objects only current adjacent zones tick
• Collision on triangle soup w/ KDtree and spatial
  index
• Lightmapper for static lighting cube maps for
  characters material-based renderer with high
  triangle throughput
• Objects tick one by one and move themselves
  simple zone-based manager
• Paging in big blocks huge continuous levels with
  persistent state

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Exceptions

• Not in final game
• Not for normal errors, only for fatal errors
• Default action is to propagate error better than
  return values (malloc example)
• Catch in individual object creation, tick
  render
• SEH is better than C EH, lets you write code in
  the catch and provides call stack
• Handler can detect attached debugger and int 3
• Bad for cross-platform

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Stack traces and error logs

• Small binary stack traces on Xbox (64 bytes)
• Parser on PC
• Mailer to coders
• VC double-click
• Used for many things
• Error messages for anything the artists can get
  wrong. Log stack traces with every error.

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Builder

• Use free POP3 client just check mail to build
  account
• Run the subject line as a command
• Batch file does syncincredibuildsubmit
• Can easily do any task so also process lipsync,
  make DVD, just use windows task scheduler

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NetSlave

• Simple distributed farm master machine controls
  a set of slaves
• Just a queue of commands, farmed out FIFO with
  dependency analysis
• Lets you use simple single-proc tools no need
  for multi-proc bugs!
• Slaves use p4 for data transfer

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Memory Management

• Systems use more or less memory at different
  times.
• Stack traced alloc tracker, parser for
  hierarchies in tabview.
• 3 heaps contiguous (20 M, relocatable), small
  block (5 M, fast), heap (used rarely at runtime).
• STL and XMemAlloc directed into our allocators
• Future separate heap for 64 meg debug data

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STL

• Saves dev time dev time is not just writing code
• STL-port configurable
• Vector is used heavily all other containers very
  rarely used
• Arrayltgt few C-style arrays, lots of vectors!

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STL - vector

• Release(), tighten(), tighten if excessive
• Modified vector growth scheme doubles on PC,
  limit at 4k on Xbox
• Vecsorted like a map, but tight in memory
  sometimes faster
• Vector_s, vector_t, vector_a note that the base
  vector class itself is 12 bytes

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Inst/Def paradigm

• Many insts created from one shared def
• CoreObject instance, made from tag, class
  factory, needs to be IOd in save games.
• Resource def, const, made from binary data
  blocks, const, shared, kept in memory across
  level loads, etc.
• Many other things use inst/def

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IOZ (the Z is for cool)

• Templated type-traits based IO system.
• Client code is very easy just call IOZ on all
  members all logic is compile-time
• Type traits and template specialization know if a
  type is binary or not, also if vectors are
  vectors of binary, etc.
• Pointer IO CoreObject or Resource?
• Resources written as Token references
• CoreObject data must be written once, but other
  pointers just write references (use the
  RefCounted table index)

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Smart Pointers

• Every type should clean itself up on destruction,
  so pointers should too.
• Other types of GC would be okay GC reduces
  errors, GC is required for exceptions. SP is the
  simplest form of GC.
• Weak Pointers a reference, not a hack 4 bytes
  4 for table entry. Table also provides index
  for IO. (2 byte table index, 2 byte UID)

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Smart Pointers, cont.

• Cant have loops use Weak or Naked for back
  pointers must have a tree-structure of
  ownership.
• Pass naked pointers avoids exposing interface
  and avoids temporaries cant do with boost style
  SP, need base class RefCounted need to be a
  little careful with this.
• Stack-trace ref tracking for ref leaks catches
  loops and other bugs.

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Tweaker and Prefs

• Text is nice for p4 diffs and searches with
  simple perl tools making spreadsheets of all
  healths, dependency finding, etc.
• Cvar no per instance overhead, handles MI. In
  the future, generic template Reflection visitor.
• GameControl system for spatial overrides and
  inheritance
• In the future more pref inheritance with
  rule-based inheritance, eg. Super Wolvark
  Wolvark w/ health2

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Resource Bundler

• Just load the level and track resource queries.
• Bundle resources for NPCs, Zones, cines, etc.
• Bundle optimization minimize bundle count,
  constrain to 64 meg limit, minimize total bundle
  size

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ArtWatcher

• Watch dirs with ReadDirectoryChangesW, copies
  content to Xbox and notifies game ArtWatched
  resources override bundled content
• Does p4 adds (we add .cpp and .h files too),
  helps artists a lot
• Right click menu for common tools
• One error on restart, ArtWatched info is lost

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Other stuff

• Skeleton LOD
• Cube Map Lighting
• Practical PSM
• Decorator Renderer
• AI System
• Animation control
• but technology is easy!

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Conclusion

• Code responds well to bad use enforces rules,
  never crashes, flexible, easily changed.
• Finish a good game on time clearly helped OW
• Hopefully one tip here is useful at your company
• No C bashing please