08: encapsulated models & protos

encapsulated models

definitions

• encapsulation :
  combining elements into a single entity
• interface :
  a common point of interaction for otherwise unrelated objects
• data hiding (encapsulation + interface) :
  keeping the object's real details away from the user and instead providing a restricted, clearly defined interface for affecting the object
• emodel :
  "An encapsulated model is an animated object containing an integrated set of dynamic attributes – e.g., shape, motion, materials (surface properties), light sources, cameras, user interfaces, sound – represented by a procedural data format (i.e., a program written in a procedural animation language).", Stephen S. May

properties of encapsulated models
(from May, 'Encapsulated Models: Procedural Representations for Computer Animation')

encapsulated models:
• have a procedural specification
• are parameterized
• can be replicated
• have components that can be related (constrained) in mathematically precise ways
• use approximations to geometric surfaces only when necessary; otherwise, exact specifications are used
• are implicit functions of time
• exhibit high levels of compression (and database amplification conversely)
• are composable
• contain components derived using simulation techniques
• contain light sources, surface materials, and atmospheric effects
• contain sound effects

vrml applications

• game programming [.pdf] (1 Mb)
• PROTO
• EXTERNPROTO
• simple PROTO / EXTERNPROTO examples:

  • PROTO Name [
       fieldType dataType fieldName /defaultValue/
    ]
    
    {
       #definition as one node (may have many internal nodes)
    }

  • map internal fields to interface with IS:
    

    PROTO ColorBox [
       exposedField SFColor color 1 1 1
       exposedField SFVec3f position 0 0 0
       field SFVec3f size 2 2 2
    ]
    
    {
       Transform {
          translation IS position
          children [
    
             Shape {
                appearance Appearance {
                   material Material {
                      diffuseColor IS color
                   }
                }
                geometry Box { size IS size }
             }
    
          ]
       }
    }

  • color box [»]
  • jumping box [»]
• implementing abstract interfaces [»]
• H-anim

examples

• pure encapsulation: Inline{}
• parameterization
  • nGon [»]
  • filled wireframe [»]
• high level animation controls
  • facial controls [5 lines] [10 lines]
  • inverse kinematics [5 lines] [10 lines]
• mathematical constraints
  • visible widgets
    • light [»]
    • sound [»]
    • transform [»]
  • lookat [»]
• time / state dependent
  • clock [»]
  • sunlight [»]
  • degradable texture
• compression
  • elevation grid
  • dynamic instancing [»]
  • procedural sphere [»]
  • iterative placement, protos with routes: light panel 1 [»]
  • iterative placement, dynamically invoked protos: light panel 2 [»]
  • fractal terrain
  • isosurfaces
  • lindenmeyer systems
• composition
  • EXTERNPROTOs with geometry sensors: othello board [»]
  • rocket clock [»]
  • galaxy [»]

links

• proto library [»]
• ken perlin [»]
• paul bourke [»]
• hugo elias [»]