VRML Nodes
VRML Nodes
Prefined VRML Shapes
Shape
Shape {
appearance NULL
geometry NULL
}
Box
geometry Box { size 2.0 2.0 2.0 }
Cylinder
geometry Cylinder {
radius 1.0
height 2.0
}
Cone
geometry Cone {
bottomRadius 1.0
height 2.0
}
Sphere
geometry Sphere { radius 1.0 }
Text
geometry Text {
string "3D Text"
fontStyle FontStyle {
family "SERIF"
style "BOLD"
}
}
Complex VRML shapes
Sets
- PointSet (set of points)
- IndexedLineSet (ordered points to draw lines)
- IndexedFaceSet (ordered points to draw 'solid' shapes)
Elevation Grids
- ElevationGrid (ordered list of heights for an x-z grid)
Extruded Shapes
- Extrusion (2D cross section swept across a 3D path)
Transformation
A Transformation node is a kind of grouping node that is used to translate, rotate and scale its children
Translation
- Used to position an object by specifying its location relative to a fixed point
VRML Translation Example
#VRML V2.0 utf8
Group {
children [
...
Transform {
translation 2.0 2.0 0.0
children [
Shape {
appearance Appearance {
material Material {
diffuseColor 1.0 0.0 0.0
}
}
geometry Box {
size 2.0 2.0 2.0
}
}
]
}
]
}
Rotation
- Pitch, rotation around X axis
- Yaw, rotation around Y axis
- Roll, rotation around Z axis
- VRML uses Quaternions to describe rotations
- R(X,Y,Z,theta), where X,Y,Z is a vector and theta is the angle
VRML Rotation Example
#VRML V2.0 utf8
Group {
children [
...
Transform {
rotation 0.0 1.0 0.0 0.785
translation 2.0 2.0 0.0
children [
Shape {
appearance Appearance {
material Material {
diffuseColor 1.0 0.0 0.0
}
}
geometry Box {
size 2.0 2.0 2.0
}
}
]
}
]
}
Scaling
- Vertices multiplied by a scaling factor to scale an object
- Can also be used to deform objects
VRML Scaling Example
#VRML V2.0 utf8
Group {
children [
...
Transform {
scale 0.5 0.5 0.5
translation 0.0 1.5 0.0
children [
Shape {
appearance Appearance {
material Material {
diffuseColor 1.0 0.0 0.0
}
}
geometry Box {
size 2.0 2.0 2.0
}
}
]
}
]
}
Appearance
The appearance of a surface is defined by setting properties that define the material from which it is made. A texture can also be defined to improve the appearance of a surface.
- Diffuse colour
- Colour of reflected light from diffuse reflection (light scattered randomly)
- Specular colour
- Colour of reflected light from specular reflection (light reflected in a regular manner)
- Emissive color
- Colour of light emitted by a the surface
- Ambient intensity
- Amount of background light the surface reflects
- Shininess
- Amount of specular reflection
- Transparency
- Transparency of the surface
- Texture
- Image (ImageTexture) or Movie (MovieTexture) mapped onto the surface
VRML Material Example
#VRML V2.0 utf8
Group {
children [
...
Shape {
appearance Appearance {
material Material {
diffuseColor 0.22 0.15 0.0
specularColor 0.71 0.70 0.56
emissiveColor 0.0 0.0 0.0
ambientIntensity 0.4
shininess 0.16
transparency 0.0
}
}
geometry Box {
size 2.0 2.0 2.0
}
}
]
}
VRML Texture Example
#VRML V2.0 utf8
Group {
children [
...
Shape {
appearance Appearance {
material Material {}
texture ImageTexture {
url "surface.gif"
}
}
geometry Box {
size 2.0 2.0 2.0
}
}
]
}
Without textures
With textures
Lighting
Light can be...
- Ambient (background)
- Directional
- Point (Omni-directional)
- Spot
VRML Lighting Example
#VRML V2.0 utf8
Group {
children [
...
DirectionalLight {
on TRUE
intensity 0.6
ambientIntensity 0.0
color 0.0 1.0 0.0
direction 0.0 0.5 -1.0
},
PointLight {
on TRUE
intensity 0.8
color 0.0 0.0 1.0
location 5.0 5.0 0.0
},
SpotLight {
on TRUE
intensity 0.6
color 1.0 0.0 0.0
location 5.0 -2.0 0.0
direction -1.0 0.0 0.0
cutOffAngle 0.5
}
]
}
Fog
Fog can be used to provide a depth cue, add atmosphere, and increase realism.
VRML Fog Example
#VRML V2.0 utf8
Group {
children [
...
Fog {
color 1.0 1.0 1.0
fogType "EXPONENTIAL"
visibilityRange 30.0
}
]
}
Without fog
With fog
Animation
- Static environments are not usually very interesting
- Interpolation is typically used to define animation in a virtual environment
- In VRML, interpolator nodes can be used to control animation
- A TimeSensor is used to generate events that can be sent to an interpolator node to set it's fraction time
- An interpolator has a set of key fractional times and a set of key values
- When the current key value of an interpolator changes, an event can be sent to another node to update a property such as position, orientation, or colour
- The type of the event generated depends on the type of interpolator node used
- A PositionInterpolator and OrientationInterpolator can be used to implement simple keyframe animation
VRML animation using an OrientationInterpolator
This is a rotating box.
VRML Animation example
#VRML V2.0 utf8
Group {
...
DEF GreenBox Transform {
children [
Shape {
appearance Appearance {
material Material {
diffuseColor 0.0 1.0 0.0
}
}
geometry Box {
size 2.0 2.0 2.0
}
}
]
},
DEF Clock TimeSensor {
enabled TRUE
cycleInterval 5.0
loop TRUE
},
DEF Path OrientationInterpolator {
key [ 0.0 0.5 1.0 ]
keyValue [
0.0 1.0 1.0 0.0,
0.0 1.0 1.0 3.14,
0.0 1.0 1.0 6.28
]
}
]
}
ROUTE Clock.fraction_changed TO Path.set_fraction
ROUTE Path.value_changed TO GreenBox.set_rotation
Interaction
- Objects need to be able to receive event messages triggered by user actions, and react on them, in order to be able to support interaction
- In VRML, sensor nodes are used to detect user actions and generate events
- A TouchSensor is used to detect touch and can generate several different output events that describe how, when and where a user touched an object
- A CylinderSensor, PlaneSensor, or SphereSensor can be used both to detect whether a shape is 'active' and to update it's position or orientation
- Other sensor node types exist to detect proximity and visibility
- Collision and Anchor nodes also detect user actions
- Typical reactions include
- Modifying a node's property
- Starting an animation
- Providing audio feedback
- Deforming an object
- Passing a value to a script node for processing
- ...
VRML Interaction using a SphereSensor
This is a box that that the user can rotate by dragging it.
VRML Interaction example
#VRML V2.0 utf8
Group {
children [
...
DEF GreenBox Transform {
children [
Shape {
appearance Appearance {
material Material {
diffuseColor 0.0 1.0 0.0
}
}
geometry Box {
size 2.0 2.0 2.0
}
}
]
},
DEF Drag SphereSensor { },
]
}
ROUTE Drag.rotation_changed TO GreenBox.rotation
Anchors
In VRML, objects can represent links that can be used to access other virtual worlds or Net resources such as Web pages.
VRML Anchor example
#VRML V2.0 utf8
Group {
children [
...
Anchor {
url "../index.html"
description "Return to lecture"
children [
Shape {
geometry Text {
string ["Go back to", "Web3D Lecture" ]
fontStyle FontStyle {
justify "MIDDLE"
}
}
}
]
}
]
}
Inline nodes
Inline nodes are used to reference other VRML files, enabling their contents to be included in a virtual environment.
The basic syntax is simply Inline { url "url_goes_here" }
Inlined nodes are loaded after the main file has been loaded.
