1. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 VRML Virtual Reality Modeling Language http://www.parallelgraphics.com/products/cortona/

2. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 VRML In addition to HTML (HyperText Markup Language), that has become a standard authoring tool for the creation of home pages, VRML provides 3D worlds with integrated hyperlinks on the Web. Home pages become home spaces.

3. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 A text file format A simple language for describing 3-D shapes and interactive environments A web standard VRML is endorsed by most 3-D graphics vendors and most web browser vendors Virtual environments are realized by a player (browser) that interprets, executes, and presents VRML files 1. What is VRML

4. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 You can write VRML files using: Any text editor Many world builder applications You can view VRML files using: A VRML browser A VRML plug-in to an HTML browser such as Cortona Player or Cosmo Player Writing and Viewing VRML Files

5. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 VRML Example boink-penrose.wrl

6. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 VRML files contain: Header Comments - notes to yourself Nodes - nuggets of scene information Fields - node attributes you can change Field Values - attribute values Node Names - names for reusable nodes Nodes have field and field values that describe their attributes. Shape nodes are used to define shapes with appearance and geometry. VRML File Format

7. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Nodes can be named, and used repeatedly DEF MyCylinder Shape {... }... USE MyCylinder... USE MyCylinder Defining Names for Nodes

8. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Shapes are the building blocks of a VRML world Primitive Shapes are standard building blocks: Box Cone Cylinder Sphere Example: prim.wrl 2. Building Primitive Shapes

9. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Understanding Shapes Shape nodes describe: geometry - form, or structure appearance - color and texture Shape { geometry... appearance... }

10. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Shape geometry is built with geometry nodes Standard, primitive geometry nodes include: Box {... } Cone {... } Cylinder {... } Sphere {... } Specifying Geometry

11. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Geometry node fields control dimensions Box { size 2.0 0.5 3.0 } Cone { height 3.0 bottomRadius 0.75 } Cylinder { height 2.0 radius 1.5 } Sphere { radius 1.0 } Dimensions are usually in meters, but they can be anything Setting Geometry Dimension

12. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 #VRML V2.0 utf8 # A Cylinder Shape { appearance Appearance { material Material { } } geometry Cylinder { height 2.0 radius 1.5 } } Examples: cylinder.wrl A Sample Primitive Shapes

13. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 children - a list of member nodes for the group Group { children [ Shape {... }, Shape {... },... ] } Understanding Groups

14. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 A Sample Group Example: space.wrl

15. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Text Shapes build text in a VRML world Signs, notes, annotation, control panels Text shapes are flat and have no thickness You can choose the font family, style, size, etc. 3. Building Text Shapes

16. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Text geometry nodes describe: text strings - the text to build font style - how to build the text Shape { geometry Text { string... fontStyle... } Understanding Text

17. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Text strings list the text to build Each string is built on its own line or column Text { string [ "SIGGRAPH 96", "Conference" ] } Building Text Strings

18. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Font styles have: family - serif, sans, or typewriter style - bold, italic, both, or none size and spacing- character size and spacing FontStyle { family "SERIF" style "BOLD" size 1.0 spacing 1.0 } Specifying Font Style

19. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Font styles also have: justification - begin, middle, end direction - left/right, up/down FontStyle { justify "BEGIN" horizontal TRUE leftToRight TRUE topToBottom TRUE } Specifying Font Direction

20. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Shape {... geometry Text { string [ "SIGGRAPH 96", "Conference" ] fontStyle FontStyle { style "BOLD" } } Examples: sigtext.wrl A Sample Text Shape

21. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 4. Transform Shapes By default, all shapes are built at the center of the world A transform enables you to 1. Translate shapes 2. Rotate shapes 3. Scale shapes

22. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 A VRML file builds components for a world A file's world components are built in the file's world coordinate system Understanding Coordinate System

23. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學  A transform creates a coordinate system that is translated, rotated, scaled relative to a parent coordinate system  Shapes built in the new coordinate system are translated, rotated, and scaled along with it Understanding Coordinate System Transform

24. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 A Transform group node controls: translation - position rotation - orientation scale - size Transform { translation... rotation... scale... children [... ] } Specifying Transform

25. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Translating positions a coordinate system in X, Y, and Z Transform { # X Y Z translation 2.0 0.0 0.0 children [... ] } Translating

26. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Rotating orients a coordinate system about a rotation axis by a rotation angle Angles are measured in radians Transform { # X Y Z Angle rotation 0.0 0.0 1.0 0.52 children [... ] } Rotating

27. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 A rotation axis defines a pole to rotate around Like the Earth's North-South pole Typical rotations are about the X, Y, or Z axes: Rotate about Axis X-Axis 1.0 0.0 0.0 Y-Axis 0.0 1.0 0.0 Z-Axis 0.0 0.0 1.0 Understanding Rotating Axis

28. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Using the Right Hand Rule

29. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Scaling grows or shrinks a coordinate system by a scaling factor in X, Y, and Z Transform { # X Y Z scale 0.5 0.5 0.5 children [... ] } Scaling

30. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Scale, Rotate, and Translate a coordinate system, one after the other Transform { translation 2.0 0.0 0.0 rotation 0.0 0.0 1.0 0.52 scale 0.5 0.5 0.5 children [... ] } Scaling, Rotating & Translating

31. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Transform { translation 4.0 0.0 0.0 rotation 0.0 1.0 0.0 0.785 scale 0.5 0.5 0.5 children [... ] } Examples: archs.wrl A Sample Transform Group

32. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 5. Controlling Appearance with Material The primitive shapes have a default emissive (glowing) white appearance You can control a shape's Shading color Glow color Transparency

33. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 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. material properties - color, transparency, etc. Shape { appearance Appearance { material... } geometry... } Understanding Appearance

34. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 A Material node controls: diffuse color - main shading color emissive color - glowing color transparency - opaque or not Material { diffuseColor... emissiveColor... transparency... } Understanding Materials

35. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Three types of Material Reflection diffuseColor  Color of reflected light from diffuse reflection (light scattered randomly) ambientIntensity  Amount of background light the surface reflects specularColor  Color of reflected light from specular reflection (light reflected in a regular manner)

36. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Colors specify: A mixture of red, green, and blue light Values between 0.0 (none) and 1.0 (lots) Color Red Green Blue White 1.0 1.0 1.0 Black 0.0 0.0 0.0 Yellow 1.0 1.0 0.0 Magenta 1.0 0.0 1.0 Brown 0.5 0.2 0.0 Understanding Colors

37. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Shape { appearance Appearance { material Material { diffuseColor 1.0 1.0 1.0 } } geometry... } Example: slabs.wrl A Sample World using Appearance

38. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Making a Shape Shining By specifying "high" values for the Material node's shininess field, direct light will cause a specular hilight (or shiny spot) on a shape By specifying a value for the Material node's specularColor field, you can control the color of specular hilights (or shiny spots) on a shape

39. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 A Sample of Shape Shining

40. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 6. Grouping Nodes Shapes can be grouped to compose more complex shapes VRML has several grouping nodes, including: Group {... } Switch {... } Transform {... } Billboard {... }

41. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 The Group node creates a basic group Every child node in the group is displayed Group { children [... ] } Understanding Basic Groups

42. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 The Transform group node creates a group with its own coordinate system Every child node in the group is displayed Transform { translation... rotation... scale... children [... ] } Understanding Transform Groups

43. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 The Switch group node creates a switched group Only one child node in the group is displayed You select which child Switch { whichChoice 0 choice [... ] } Understanding Switching Groups

44. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 The Billboard group node creates a group with a special coordinate system Every child node in the group is displayed Coordinate system is turned to face viewer Billboard { axisOfRotation... children [... ] } Understanding Billboard Groups

45. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 A rotation axis defines a pole to rotate round Similar to a Transform node's rotation field, but no angle (auto computed) Billboard Rotation Axes

46. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Group { children [ Billboard { axisOfRotation 0.0 1.0 0.0 children [... ] }, Transform {... } ] } Example: robobill.wrl A Sample Billboard Group

47. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Inlining World Components VRML files describe components of a world: tables, chairs, lamps, walls, floors, doors Inlining combines files to build larger components: rooms, buildings, neighborhoods

48. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 The Inline node creates a special group Children are read from a VRML file selected by a URL Every child node in the group is displayed Inline { url "table.wrl" } Understanding Inlining

49. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學... Inline { url "table.wrl" },... Transform { translation... children [ Inline { url "chair.wrl" } ] },... Example: dinette.wrl A Sample Inlined File

50. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Adding Anchors to Your World Any shape or group of shapes can be an anchor Selecting the anchor jumps to a new VRML world Like the syntax of HTML

51. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 The Anchor node creates a group Every child node in the group is displayed Selecting any child jumps to VRML file specified by URL The anchor can have a description string Understanding Anchors

52. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 A Sample Anchor Anchor { url "stairway.wrl" description "Floating Stairs" children [... ] } Example: anchor.wrl

53. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 7. Coordinate based Geometry: Points, Lines, and Faces Create more complex shapes than primitives Generate more efficient VRML worlds Have more control and flexibility than primitives

54. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Hard to build using primitives There's a more flexible way to describe shapes...

55. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 (1) Specifying Coordinates (Define location of "dots “ ) Location of dots (points) using Coordinate node Coordinate { point [ 2.0 1.0 3.0, 4.0 2.5 5.3,... ] } (2) Creating Geometry Using Coordinates (Connect the dots ) Three nodes have a coord field which accepts a Coordinate node PointSet IndexedLineSet IndexedFaceSet Describe Geometry in two steps

56. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 PointSet Node A dot is drawn at each point PointSet { coord Coordinate { point [... ] } color Color { color [... ] } } No control over size of dot Also supports color field for Color node Example: ptplot.wrl

57. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Straight lines are drawn between points IndexedLineSet { coord Coordinate { point [... ] } coordIndex [ 1, 0, 3, -1,... ] } Example: lnplot.wrl IndexedLineSet Node

58. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 coordIndex [ 1, 0, 3, -1,... ] Indexes reference ordered points of coord field Index order is arbitrary (eg: 1, 0) Indexes are Zero-based (eg: 0) Can skip coordinates (eg: 0, 3) Poly-line can be many points (eg: 1, 0, 3) End of poly-line (eg: -1) Multiple poly-lines (eg:...) CoordIndex Value

59. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 IndexedFaceSet Node Faces are drawn within perimeter of points IndexedFaceSet { coord Coordinate { point [... ] } coordIndex [ 1, 0, 3, -1,... ] } Example: vase1.wrl

60. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 8. Binding Color to Coordinate based Geometry Override Material node (overall color) Better color control for IndexedFaceSet, IndexedLineSet, PointSet, and ElevationGrid nodes Apply color per-face or per-vertex

61. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 The Color node is used as the color field value of IndexedFaceSet, IndexedLineSet, PointSet or ElevationGrid nodes The Color node contains a list of RGB values Color { color [ 1.0 0.0 0.0,... ] } Color Node

62. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 IndexedFaceSet { coord Coordinate {... } coordIndex [... ] color Color { color [ 1.0 0.0 0.0,... ] } colorIndex [ 3, 0, 1,... ] colorPerVertex TRUE } IndexedFaceSet using a color node

63. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 In IndexedFaceSet, IndexedLineSet nodes When colorPerVertex is TRUE, specify one color index per coordinate index (don't forget to account for the - 1's !) When colorPerVertex is FALSE, specify one color index per face or line (eg. per -1) ColorPerVertexField

64. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Colored triangles: per-face and per-vertex Example: color_face.wrl, color_vertex.wrl A sample Color Binding

65. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 9. Mapping Texture Wrap images around shapes Apply an image as an opaque "decal" Apply an image with transparent "holes" Wrap a movie's images around shapes Add realistic appearance to shapes

66. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Texture color overrides Material node color Appearance node's texture field wraps an image around geometry The texture can be an ImageTexture, MovieTexture, or PixelTexture Texture Property

67. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Appearance { material Material {} texture ImageTexture { url "myimage.jpg" } } ImageTexture Node

68. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Appearance { texture MovieTexture { url "mymovie.mpg" speed 1 loop FALSE } } MovieTexture Node

69. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 The PixelTexture node contains data stored as width, height, number of channels, followed by width*height hex values representing the image Example: A 2x4 RGB image PixelTexture { image 2 4 3 0xFF0000 0x00FF00 0 0 0 0 0xFFFFFF 0xFFFF00 } PixelTexture Node

70. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 A sample Texture Mapping Example: can.wrl

71. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 10. Texture Control When applying a texture, you sometimes need to control: What piece of a texture is extracted from an image How the piece of texture is applied to a face

72. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 I. Build cookie cutter of desired size and shape II. Set position, rotation and scale over sheet III. Extract a piece of dough from sheet, and apply extracted piece of dough onto shape Three steps to apply a piece of texture

73. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 texCoord TextureCoordinate { point [ 0.2 0.2, 0.8 0.2, 0.8 0.8, 0.2 0.8 ] } Note: texCoord is a field of IndexedFaceSet, ElevationGrid nodes I. Build Cookie Cutter Shape

74. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Appearance node's textureTransform field sets position, rotation and scale of cutter over the dough TextureTransform { translation 0.5 0.5 rotation 0.0 scale 2.0 2.0 } II. Texture Transform

75. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 IndexedFaceSet extracts and applies the piece of texture to faces IndexedFaceSet { coord Coordinate {... } coordIndex [... ] texCoord TextureCoordinate {... } texCoordIndex [... ] } III. Extract and Apply Texture

76. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Texture Transform: Scale TextureTransform { scale 3.0 3.0 }

77. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Texture Transform: Transform TextureTransform { translation 0.166 0.0 } # 1/6

78. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Texture Transform: Rotation TextureTransform { rotation 0.785 # 45 degrees }

79. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 11. Shading Control using Normals Normals define the direction of faces Faces used to approximate smooth surfaces, but normals can be used to control whether a surface is flat or smoothly shaded Default Normals are often good enough !

80. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 To control shading of ElevationGrid, and IndexedFaceSet nodes Specify normal, normalIndex, and normalPerVertex field values or … Set the creaseAngle field to automatically generate normals Shading Control Tools

81. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 The normal field specifies face direction Normal { vector [ 1.0 0.0 0.0, 0.0 1.0 0.0, 0.0 0.0 1.0,... ] } Normal Node

82. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 CreaseAngle Field If angle between adjacent faces is larger than creaseAngle, then faces are flat shaded. If angle between adjacent faces is smaller than creaseAngle, then faces are smoothly shaded.

83. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Shading Flat Surface colored uniformly according to its orientation towards light sources Faceted appearance Smooth (Gouraud) Each vertex is assigned a color according to its orientation towards light sources and intermediate points are a blend of the surrounding vertex colors Smooth shading Can be too smooth (can smooth away detail)

84. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 12. Lights Light sources illuminate and effect shading of faces Several types of lights available for maximum control Lights do not cast shadows

85. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Three different light nodes PointLight, DirectionalLight, SpotLight Standard fields (common to all 3) and defaults: on TRUE intensity 1.0 ambientIntensity 0.0 color 1.0 1.0 1.0 Light Node

86. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Point lights have a location and glow radially PointLight { # Standard fields, plus: location 0.0 0.0 0.0 radius 1.0 # specifies the maximum distance for the light rays to travel attenuation 1.0 0.0 0.0 } PointLight Node

87. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Directional lights point in a specified direction DirectionalLight { # Standard fields, plus: direction 1.0 0.0 0.0 } Directional Light

88. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Spot lights point in a direction and focus in a cone SpotLight { # Standard fields, plus: location 0.0 0.0 0.0 direction 1.0 0.0 0.0 cutOffAngle 0.785 radius 1.0 attenuation 1.0 0.0 0.0 } Spot Light

89. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Backgrounds add realism to VRML worlds Backgrounds are cheaper than using geometry Backgrounds always stay "infinitely distant" 13. Background

90. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Two types of background (can be combined) Backdrop: Sky and Ground color gradients (Mapped to inside of a sphere) Panorama: Surrounding images (Mapped to inside faces of a cube) Backdrop vs. Panorama

91. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 xxxColor specifies color values xxxAngle specifies angles in radians (0.. PI) Background { groundColor [.14.28 0,.09.11 0, 0, 0, 0 ] groundAngle [.785, 1.57 ] skyColor [.02 0.26,.02 0.65, 0, 0, 0 ] skyAngle [.785, 1.57 ] } Example: m_bkgd1.wrl Specifying Backdrop

92. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Specifying Panorama xxxUrl fields specify images Images overlay backdrop (if any) (backdrop shows through transparent regions) Background { frontUrl "f_image.jpg" backUrl "b_image.jpg" leftUrl "l_image.jpg" rightUrl "r_image.jpg" } Example: m_bkgd2.wrl

93. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Fog is a "special effect" for added realism Exact effects (if any) are browser dependent Colors "fade" to a specified value over distance 14. Fog

94. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 VRML Fog Example #VRML V2.0 utf8 Group { children [... Fog { color 1.0 1.0 1.0 fogType "EXPONENTIAL" visibilityRange 30.0 } ] } Fog Node

95. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Fog can be used to provide a depth cue, add atmosphere, and increase realism Colors fade to value specified in color field. visibilityRange specifies distance at which fog color predominates. Value 0 disables node. Example: fog1.wrl, fog2.wrl, fog4.wrl Fog Example

96. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 15. Level of Detail LOD (Level Of Detail): Can reduce "upfront" download time (have simpler models loaded first) Can improve frame rate (use simpler models for far away objects) Useful as a depth cue

97. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 An object is rendered with more detail when a user is close to it than when the user is far away An object can have several levels of detail, each valid for a different range of distances Hardware assist the transition between levels of detail to make them as smooth as possible Levels of Detail

98. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Range specifies distance from center of LOD to viewer (for each transition between levels) Grouping node (one child displayed at a time). LOD { range [... ] center 0 0 0 level [... ] } LOD Node

99. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Using Ranges List range values in increasing order. Define children in order of highest to lowest detail. For N ranges, provide N+1 children range [ 20, 100 ] < 20 m 1st child used >= 20 & < 100 m 2nd child used >= 100 m 3rd child used Example: m_lod1.wrl, m_lod2.wrl

100. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Making good levels of detail is tricky. Two or three levels are usually enough. Remove "details" that are easy to remove Simplify geometry if appropriate Everything is a hint! (Browser decides which level to display.) LOD can get large, use Inline for some kids. Don't use LOD to simulate behavior. center is not a translation. Optimizing Strategy

101. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Primarily used to define named camera positions Browser will usually present a list of viewpoints using their description strings. Browser may animate between viewpoints. 16. Controlling the View Point

102. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Using Viewpoint Orientation defines direction of view and "up" direction (relative to default orientation).  Rotation Viewpoint { position 0 0 9 orientation 0 0 1 0 description "DefaultView" } Example:m_vwpts1.wrl

103. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Sound adds realism and allows special effects General uses: 1. Continuous background (traffic, muzak,...) 2. Continuous localized (waterfall, monster,...) 3. Triggered (bumping wall, clicking switch,...) 17. Adding Sound

104. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 A Signal AudioClip or MovieTexture Node Think of this as the "CD player" A Location Sound Node Think of this as the "speaker" CD Player vs. Speaker

105. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 AudioClip specifies a signal Typically.wav or.mid file Start time, pitch, looping or not Sound specifies a place Location, direction, attenuation region Intensity, "spatialized" or not AudioClip vs. Sound

106. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Playback started by: Setting startTime field Setting loop to TRUE AudioClip { url [... ] loop FALSE startTime 0 } AudioClip Node

107. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Audible if clip is playing and node is "traversed" Sound { source AudioClip {... } intensity 1 location 0 0 0 direction 0 0 1 spatialize TRUE } Basic Sound Node

108. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Advanced Sound Node Defines two ellipsoids aligned with direction Full intensity within inner ellipsoid Intensity drops to zero between inner and outer Sound {... minFront 1 maxFront 10 minBack 1 maxBack 10 }

109. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學

110. In AudioClip node set loop field to TRUE (Will start on entering world) In Sound node set minFront and minBack to large values. spatialize to FALSE (stereo clip will play as stereo) Example: m_sound1.wrl Continuous Background Sound

111. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Set AudioClip node same as previous. In Sound node set position and direction minFront, maxFront,... values spatialize to TRUE (clip will play as monaural) Example: m_sound2.wrl Continuous Localized Sound

112. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 In AudioClip node set loop field to FALSE (for a "one shot") startTime each time sound should play (discussed later) In Sound node set location, direction,... spatialize to TRUE (usually) Example: m_sound3.wrl Triggered Sound

113. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 18. Fields and Events Each node has specific fields and events 1.Field: A stored value (parameter), eg. url 2.EventIn: An event node can receive, eg. set_url 3.EventOut : An event node can send, eg. url_changed Event: A message that contains a data value

114. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 Routes Route: Connects an EventOut to an EventIn A Route is not a node! Output type must match input type exactly Output may connect to multiple inputs (fan-out) Multiple outputs may connect to single input (fan-in) Nodes must be named in order to use Routes

115. CVVR Lab.@ National Dong Hwa Univ. 國立東華大學 DEF NODE1 Collision {... } DEF NODE2 AudioClip {... } ROUTE NODE1.CollideTime TO NODE2.startTime Example: m_route.wrl Route Example