Intro to Virtual Reality Markup Language

1
Intro to Virtual Reality Markup Language
2
Overview

• What is VRML?
• Adding a VRML file to your web page
• VRML Basics with example code
• Shapes, transforms, lights
• Info about the lab

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What is VRML?

• Virtual Reality Markup Language
• Also called Vermal
• A programming language for creating 3D worlds.
• Can be viewed from a webpage (with a plugin)
• Allows users interaction and exploration

4
What you need to do VRML

• Text editor
• Emacs (linux, windows, unix)
• Notepad, Wordpad (windows)
• Web browser
• Mozilla
• Internet Explorer
• Opera
• Netscape
• Plugin
• Cortona (the one we use)
• CosmoPlayer

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Where can I find that stuff?

• Emacs for Windows
• http//www.xemacs.org/Download/index.html
• Cortona plug-in
• http//www.parallelgraphics.com/products/cortona/
  
• Opera, Mozilla och Netscape
• http//www.netscape.com/
• http//www.opera.com/
• http//www.mozilla.org/

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Adding VRML to your web site

• Put VRML code in a separate file.
• Filename should end with .vrml or .wrl
• Use the embed command in HTML to add the file.
• I.E.,
• lt EMBED SRC"test.vrml" WIDTH600 HEIGHT200 gt

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The basics

• File header
• Comments
• Brackets
• Shapes
• Colors
• 3D coordinates and transforms
• Lights

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File Header

• IMPORTANT Your VRML file must always start with
  the with
• VRML V2.0 utf8
• Tells that the file is a VRML file
• Tells the file is compatible with version 2.0 of
  the VRML specification
• Tells that the file is encoded with the
  international standard utf8
• The VRML header not found or unsupported
  encoding type

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Comments

• Comments can be added to your code by starting a
  line with a . So
• Add this to your VRML code and everything
• will be ok
• Do not add this to your VRML without a
• Why use comments?
• It helps you formulate thoughts and keep focused
  on what you are working on.
• It makes it easier to come back later to your
  code and remember what it does.
• It makes it easier for other people to understand
  your code.

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Brackets

• Brackets and are used in order to group
  things together logically.
• Using indentation with brackets is VERY important
  and makes code much easier to read

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Brackets example

• Shapegeometry Box size 2.0 2.0 2.0appearance
  Appearancematerial Material diffuseColor 0 1 0
  
• Is much harder to read than
• Shape
• geometry Box size 2.0 2.0 2.0
• appearance Appearance
• material Material diffuseColor 0 1 0
  

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Shapes

• There are four primitive shapes in VRML.
• Box, Sphere, Cone and Cylinder
• The general syntax for a shape is
• Shape
• The geometry includes physical features like the
  shape and size
• geometry
• appearance Appearance
• The appearance includes the color etc.
• material Material

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Some example shapes

• A red sphere
• Shape
• Create a shpere with a radius of 2
• geometry Sphere radius 2
• appearance Appearance
• diffuseColor referes to the color of a
  shape
• lets make the sphere red
• material Material diffuseColor 1
  0 0
• --------------------------------------------------
  ------------------------------
• A blue box
• Shape
• geometry Box size 2.0 2.0 2.0
• appearance Appearance

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Color

• Colors are described in VRML using RGB values.
• Example colors
• 1, 1, 1 White
• 0, 0, 0 Black
• 1, 0, 0 Red
• 0, 1, 0 Blue
• 0, 0, 1 Green
• 1, 1, 0 Yellow
• 0, 1, 1 Cyan
• 1, 0, 1 Magenta
• Dark Colors
• .5, 0, 0 Dark Red
• 0, .5, 0 Dark Blue

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3-Dimentional Coordinates

• Points are represented by 3 variables
  corresponding to the x,y and z axis.
• The point (0,0,0) is referred to as the origin
• Other points are referenced in relation to the
  origin. E.g. (1,1,1), (-1,0,0)

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Placing objects in VRML

• Use the Transform function along with 3D
  coordinates
• For example,
• Transform
• translation 1 1 1
• children
• objects (shapes etc.) added here will be at
  the point 1 1 1
• objects added here will be at the origin
• Note Transforms can also change scale and cause
  rotations but you dont need to know this to do
  the labs.

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Lighting

• VRML contains 3 types of lights.
• Point light shoots light out in all directions
  from a single point.
• Spot light shoots light in a single direction
  from a single point.
• Directional light shoots light rays parallel to
  a single direction. Only effects objects in the
  same group as the light.

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A directional light

• Group
• children
• DirectionalLight
• on TRUE
• intensity 1
• ambientIntensity 0
• color 1 1 1
• direction 0 0 -1
• Shapes created here will be effected by the
  directional light
• Shapes here will not be effected by the light
  because they are outside the group

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The lab

• In case you have not read the web page yet
• 3 shapes, 1 light
• There is a helper file to get you started.

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An important tip

• WATCH THOSE BRACKETS!
• Easy to mess up.
• Can take a long time to figure out what is going
  wrong.