02: intro to vrml

vrml overview

• vrml is a scene description language, related to open inventor (ancestor of openGL)
• scene graph = directed acyclic graph of nodes (a node tree)

• 54+ nodes: for geometry, transformation, color, texture, sound, etc.
• node cheat sheet [»]
• node reference [»]
• nodes have family tree relationships (parents, siblings, children)
• node characteristics are specified via fields

• 20 field types, similar to variables in c, java, etc.
• SF = single field, MF = multi-field
• basic data types:
  

  Bool	boolean value	TRUE, FALSE
  Float	rational (floating point) number	-63.012, 3.14159, 1.03e25
  Int	whole (integer) number	-5, 0, 299
  Node	scene graph element	ImageTexture{}, IndexedFaceSet{}, Coordinate{}
  String	sequence of characters	"", "43", "hello, world!"

• vrml file = ascii text, can be zipped for considerable compression
• required header: #VRML V2.0 utf8
• # for single line comments
• general syntax is:
  

  NodeName {
    fieldName fieldValue
  }

• case is important! Shape is not the same as shape
• commas and whitespace are not required for validity (just readability)
• publishing step can remove non-critical data for smallest file size

vrmlpad

• cut and paste a simple vrml file:
  

  #VRML V2.0 utf8
  
  Background {
    skyColor .33 .33 .33
  }
  NavigationInfo {
    type "EXAMINE"
  }
  Viewpoint {
    description "start"
    position 0 0 8
  }
  
  Shape {
    appearance Appearance {
      material Material {
        diffuseColor 0 .2 .4
      }
    }
    geometry Box {
      size 3 2 1
    }
  }

• things to try:
  • set up F1 to point to Annotated VRML Reference [»]
  • adjusting syntax coloring, node folding, error checking to your liking
  • auto-completion (pops up while typing or CTRL-SPACE, use arrow keys to hilite, ENTER to select)
  • navigating scene graph through tree view
  • auto-formatting (CTRL-SHFT-F)
  • quick preview (F5)

vrml warm-up

• titling your work
  

  WorldInfo{
     title "My Vrml Work"
     info [
        "a basic shape"
        "made by me"
     ]
  }

• a basic shape
  

  Shape {
    geometry NULL
  }

• geometry primitives (possible nodes to replace NULL above)
  • Box{}
  • Cone{}
  • Cylinder{}
  • Sphere{}
• example [»]

task01 [»]