OpenSource Graphics Development with the Delta3D Game Engine

1
Open-Source Graphics Development with the
Delta3D Game Engine

• Chris Osborn
• Lead Software Engineer
• Delta3D, MOVES Institute
• cwosborn_at_nps.edu

2
Agenda

• Why Use Open-Source Software?
• Overview of the Delta3D Game Engine
• Building a Delta3D Application
• STAGE the Simulation, Training, And Game Editor
• Building Actor Libraries for STAGE
• Questions

3
Why Use Open-Source Software?

• Often cross-platform...
• Windows, Linux, OSX, BSD, and more
• Always the lowest bid!
• No vendor lock-in
• Freedom to modify and enhance code
• Often has commercial-friendly licensing

4
Licensing

• The Delta3D libraries are licensed under the
  LGPL.
• Lesser GNU Public License
• http//www.gnu.org/copyleft/lesser.html
• Applications may use a LGPL library and retain a
  commercial license.
• In contrast to the GPL, where programs that use a
  GPL library automatically fall under the GPL
  themselves.
• The STAGE source code is licensed with the GPL.

5
Whats in Delta3D?

• Libraries
• dtUtil General utilities
• dtCore Core engine
• dtABC Application Base Classes
• dtAudio Audio
• dtChar Characters
• dtGUI CEGUI implementation
• dtHLA HLA/RTI networking
• dtScript Python scripts
• dtTerrain Terrain framework
• dtDAL Dynamic Actor Layer
• dtGame GameManager
• dtActors STAGE export of dtCore
• dtBSP BSP Library
• dtInspector FLTK debugging tool

• Utilities
• bspCompiler
• STAGE
• hlaStealthViewer
• psEditor Particle Systems
• Viewer Model Viewer

6
Architecture
7
Building a Delta3D Application

• Rapid, iterative development is good.
• Delta3D provides base classes to facilitate this
  style of development.
• Derive from dtABCApplication to instantly have
  a working program with a window, scene, mouse
  keyboard callbacks, and an entry point into the
  frame loop.

8
dtABCApplication

• void Confg()
• Setup your scene here
• void KeyPressed()
• Keyboard callback
• void ButtonPressed()
• Mouse callback
• void PreFrame()
• Per-frame callback
• It is safe to add and remove objects from the
  scene here

9

• Lets take a look at a sample application.

10
STAGE

• The Simulation, Training, And Game Editor
• Assemble 3D scenes by placing actors and
  modifying their properties
• Contains core library of actors supporting almost
  all Delta3D classes
• Extensible plug-in interface for your own actors
• Intuitive user-interface
• Supports triggers and basic scripting

11

• Lets take a look at STAGE.

12
dtDAL STAGE Architecture
13
Building an Actor Library

• Create your Actor classes.
• Wrap the classes using ActorProxies.
• Export the ActorProxies in a shared library.
• Load the library via a GUI in STAGE.

14
Creating Actors

• Here, Actor refers to a custom Delta3D classes
  that you wish to use in STAGE.
• Actor classes must have a base class of
  dtCoreDeltaDrawable.
• An Actor Property is any member variable you wish
  to manipulate in STAGE. For example, a collision
  shape.
• You must define Gets Sets for all of the Actor
  Properties.

15

• Lets take a look at a custom Actor the
  TessellationActor.
• It represents a flag-like object that can be
  assigned a texture.

16
Wrapping classes with ActorProxies

• An ActorProxy is a generic interface to Actor
  Properties. They allow STAGE to manipulate Actor
  without understanding the Actor type.
• Custom ActorProxies dervie from
  dtDALActorProxy, dtDALTransformableActorProxy,
  etc.
• Often, you will need to wrap the Gets/Sets on the
  Actor itself to fit the interface required by
  STAGE.
• void BuildPropertyMap()
• Associates Properties with Gets/Sets.

17

• Lets take a look at the ActorProxy for our
  TessellationActor.

18
Exporting ActorProxies to a Library

• Finally, we must export the ActorProxy into a
  shared library that STAGE can use.
• On Windows, this would be a .dll.
• On Linux, the library is a .so.
• ActorProxy Libraries derive from
  dtDALActorPluginRegistry.
• void RegisterActorTypes()
• Defines which Actors are in this library.

19

• Lets take a look at the library containing our
  TessellationActorProxy.

20
Loading a ActorProxy Library in STAGE

• Edit -gt Map Libraries... -gt Import Library
• Then youll be able to use your Actor in STAGE!
• Oh, and if you want to open your map at another
  time, make sure you custom library is somewhere
  in your PATH (Windows) or LD_LIBRARY_PATH (Linux).

21

• Lets go check out our new Actors in STAGE.

22
Loading a Map from an Application

• dtDALProjectGetInstance().GetMap(MyMap)
• This function returns a reference to the map with
  the name MyMap.
• void LoadMap( dtDALMap map )
• You can then pass that reference into this
  function, which loads the map into the default
  Scene in your application.

23

• Lets see how to load map with
• some good ol C.

24
Finding Proxies in a Map

• dtDALMapFindProxies(vector,name)
• vector is of type stdvectorlt osgref_ptrltActorP
  roxygt gt
• name is of type stdstring (wildcards allowed,
  i.e. )
• This function will fill the vector with proxies
  that match the wildcard string name.
• Once you have the matching ActorProxies you can
  call ActorProxyGetActor() to return the
  internal Actor.
• Then you should dynamic_cast the Actor to your
  Actors static type.

25

• Lets see how to find our TessellationActorProxy
  in a Map.

26
Thank you!

• Questions?
• Chris Osborn
• cwosborn_at_nps.edu
• osb on the forums, come say hi!
• http//www.delta3d.org/IISECTutorial.zip