Outline

• Introduction to CAVERNsoft
• CAVERNsoft w/ OpenGL & CAVElib
• Introduction to Iris Performer
• CAVERNsoft + Performer + pfCAVE = LIMBO

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Introduction to CAVERNsoft

• What is CAVERNSoft?
• "a C++ hybrid-networking/database library optimized for the rapid construction of collaborative VR applications."
• simplify coding effort and improve distribution efficiency
• Concepts
• IRB - Information Request Broker
• Channels - determine network characteristics (e.g. TCP/UDP/Multicast, desired bandwidth, latency, jitter)
• Keys - handles on (pointers to) pieces of data to be shared through IRB
• Links - links local and remote key; defines what happens when data is sent or recieved; (e.g. active or passive updates, synchornization: automatic (based on timestamp), forced, etc)
• Non-graphical example
• irblisten.c++
• irbsend.c++

CAVERNsoft w/ OpenGL & CAVElib

• Simple example
• displayball.c++
• bounceball.c++
• single graphics server, possibly multiple (non-graphical) computation clients
• run "displayball" on local machine (e.g. trager), run "bounceball trager" on remote machine
• note the lack of a locking mechanism
• More of the same
• displayballs.c++
• bounceballs.c++
• More complex
• chess_server.c++
• chess_client.c++
• single (non-graphic) state server, multiple graphical clients
• run "chess_server" on remote machine (e.g. trager), run "chess_client trager" on local machine
• chess_full.c++ & head.h by John Huffman

Introduction to Iris Performer

• API somewhere between VRML and OpenGL
• high-level, object-oriented, and scene-graph-based like VRML
• direct programming and simulation control like OpenGL
• Features:
• File Importers - use perfly <filename> to see if your format works
• Built-in multi-processing - APP/CULL/DRAW processes (view frustum culling)
• Built-in shared memory - multi-buffering of scene graph reduces need for explicit shared memory calls and locks
• Object-oriented; build scene graph dynamically: i.e. create new object, set parameters, add to graph (addChild command)
• LOD, Billboards, Animation Paths, Switches, Morphs, special effects all built-in
• delivers best possible performance from graphics hardware (without lots of hand-tuning of OpenGL code); performance measurement capabilities (more)
• Available under Irix and Linux
• Works best for visual simulation applications (e.g. campus model, virtual display case, CAVE art) (as opposed to visualization applications.)
• OpenGL :       
• Performer:        
• Programming:
• library (& man page) organization (on mammoth)
• libpr - low level (types, math, state settings)
• libpf - high level (scene graph components, "objects")
• libpfdb - database loader libraries
• libpfui - user interface widgets (not applicable for CAVE use)
• Insight books (on mammoth)
• IRIS Perfomer Getting Started Guide
• IRIS Performer Programmer's Guide
• IRIS Performer Class Reference for C/C++ Programmers
• Performer CAVE Programming
• pfCAVE Library
• Dave Pape's Performer Programming Resources
• Presentation
• Performer by Example
• behaviors by overriding APP callback
• Examples:
• key for interaction is the pfDCS (Dynamic Coordinate System) node
• equivalent to the Transform node in VRML
• pfSCS (Static Coordinate System) are more efficient for static transformations
• Note: Performer uses Z-up right-handed coordinate system
• pfbounce.c++
• pfnav.c++
• pfnav.traversal.c++

LIMBO

• LIMBO is a fully-functional collaborative VE made from a combination of CAVERNsoft, Performer, and pfCAVE
• Features:
• customizeable avatars
• navigation with collision detection (standard 4 DOF navigation + fly-to navigation)
• store & forward audio
• persistent database
• may load any Performer-compatible object (use delimbo)
• database objects may be manipulated and deleted