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Chapter 5 – Animation in VRML

Chapter 5 – Animation in VRML. Understanding Animation and Time. Animation is the change of something as time progresses

edwardjenkins
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Chapter 5 – Animation in VRML

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  1. Chapter 5 – Animation in VRML

  2. Understanding Animation and Time • Animation is the change of something as time progresses • The change may be to a coordinate system’s position, thereby causing the coordinate system and a group of shapes built within it to translate from one location to another as the time progresses • The change caused by animation can be to a coordinate system’s orientation and scale as well

  3. Understanding Animation and Time • Any animation requires two elements: • a clock to control the playback of the animation • a description of how something changes during the course of the animation • We can create a clock using the TimeSensor node • The node provides features for starting and stopping the animation and controlling how quickly the animation plays

  4. Understanding Animation and Time • To describe the change to occur during an animation, we use PositionInterpolator and OrientationInterpolator nodes • To create animation, we need to use ROUTE syntax to wire an output from a TimeSensor node to the input of a PositionInterpolator or OrientationInterpolator node • Once wired, the TimeSensor node’s clock can start and event will flow from the TimeSensor node to the Interpolator and from there to the Transform node causing the node’s coordinate system to translate, rotate and scale as animation plays back

  5. Understanding Animation and Time • Time is measured either absolutely or relatively • Absolute time represents the real-world clock • For relative time, it could consider as starting an animation at fractional time 0.0 and running to the end at fractional time 1.0 • The length of time between fractional time 0.0 and fractional time 1.0 is independent of absolute time • A time sensor could create a time loop that cycles from fractional time 0.0 to fractional time 1.0. Using this feature, we could loop the animation endlessly until we stopped the animation

  6. Understanding Key Frame Animation • An animation description must provide a position or orientation for each new time as the animation’s fractional time progresses from 0.0 to 1.0 • The most straightforward is to use a table of orientations, one for each possible fractional time between 0.0 and 1.0 • Unfortunately there is infinite number of possible fractional times between 0.0 and 1.0 making it impossible to construct this table

  7. Understanding Key Frame Animation • An animation description must provide a position or orientation for each new time as the animation’s fractional time progresses from 0.0 to 1.0 • The most straightforward is to use a table of orientations, one for each possible fractional time between 0.0 and 1.0 • Unfortunately there is infinite number of possible fractional times between 0.0 and 1.0 making it impossible to construct this table

  8. Understanding Key Frame Animation • Instead we use a technique called keyframe animation where a position or rotation is specified for only a few key fractional times known as key values. • VRML will then make use of these key values to fill in the values in between as needed. The PositionInterpolator and OrientationInterpolator nodes both use a list of key fractional times and key values to describe an animation.

  9. Understanding Key Frame Animation • To wire an interpolator node into animation circuit, the fraction_changed eventOut of a time sensor is routed to the set_fraction eventIn of the interpolator. • Each time the time sensor outputs a new fractional time, the interpolator uses the input fractional time, computes a new position or rotation, the outputs it via its value_changed eventOut. • That output is then in turn wired to a Transform node to cause the node’s coordinate system to translate and rotate as the time sensor ticks away.

  10. The TimeSensor Node • The TimeSensor node creates a clock that generates events to control animations as follows: TimeSensor { enabled TRUE # exposedField SFBool startTime 0.0 # exposedField SFTime stopTime 0.0 # exposedField SFTime cycleInterval 1.0 # exposedField SFTime loop FALSE # exposedField SFBool isActive # eventOut SFBool time # eventOut SFTime cycleTime # eventOut SFTime fraction_changed # eventOut SFFloat }

  11. Understanding Key Frame Animation • The value of the enabled exposed field specifies whether the time sensor is turned on or off • If the field value is TRUE, then the time sensor is on and the test of the node’s field are used to control the output of the sensor • If the value is FALSE, then the time sensor is off and no outputs are generated except those in response to changing an exposed field • The value of the startTime exposed field specifies the time at which if the sensor is enabled, it beings outputting events via its eventOuts

  12. Understanding Key Frame Animation • The value of the stopTime exposed field specifies the time at which the time sensor stops output events • The value of the cycleInterval exposed field specifies the length of time the time sensor takes to vary its fractional time output from fractional time 0.0 to 1.0 • The value of the loop exposed field specifies whether the time sensor loops or not. If the field value is set to TRUE, the time sensor outputs floating point fractional time values from 0.0 to 1.0 during the cycle interval

  13. Understanding Key Frame Animation • The isActive eventOut outputs a single TRUE event value when the time sensor becomes active and starts outputting events • The time eventOut outputs an absolute time event value continuously as long as the timesensor is generating events • The cycleTime eventOut outputs an absolute time event value each time the cycle starts over again • The fraction_changed eventOut outputs a fractional floating point time value between 0.0 and 1.0 as the time sensor progresses through a cycle

  14. The PositionInterpolator Node • The PositionInterpolator node describes a series of key positions available for use in an animation PositionInterpolator { key [ ] # exposedField MFFloat keyValue [ ] # exposedField MFVec3f set_fraction # eventIn SFFloat value_changed # eventOut SFVec3f }

  15. The PositionInterpolator Node • The value of the key exposed field specifies a list of key fractional floating point times and typically the range of these time falls between 0.0 and 1.0 • The keyValue exposed field specifies a list of key positions. • Each key position is a group of 3 values containing an X, a Y and a Z floating value making up a 3D coordinate or translation distance • The set_fraction eventIn is used in wiring a route from the fraction_changed eventOut of a TimeSensor node

  16. The OrientationInterpolator Node • The OrientationInterpolator node describes a series of key rotations available for use in an animation OrientationInterpolator { key [ ] # exposedField MFFloat keyValue [ ] # exposedField MFRotation set_fraction # eventIn SFFloat value_changed # eventOut SFRotation }

  17. The OrientationInterpolator Node • The value of key is defined as before. • The keyValue exposed field specifies a list of key rotations. • The key fractional times and rotations are used together so that the first key fractional time specifies the time for the first key rotation and so on • The rest of the fields work exactly as mentioned in the prior section

  18. Animating Position #VRML V2.0 utf8 Group { children [ # Moving box DEF Cube Transform { children Shape { appearance Appearance { material Material { } } geometry Box { size 1.0 1.0 1.0 } } },

  19. Animating Position # Animation clock DEF Clock TimeSensor { cycleInterval 4.0 loop TRUE }, # Animation path DEF CubePath PositionInterpolator { key [ 0.00, 0.11, 0.17, 0.22, 0.33, 0.44, 0.50, 0.55, 0.66, 0.77, 0.83, 0.88, 0.99 ]

  20. Animating Position keyValue [ 0.0 0.0 0.0, 1.0 1.96 1.0, 1.5 2.21 1.5, 2.0 1.96 2.0, 3.0 0.0 3.0, 2.0 1.96 3.0, 1.5 2.21 3.0, 1.0 1.96 3.0, 0.0 0.0 3.0, 0.0 1.96 2.0, 0.0 2.21 1.5, 0.0 1.96 1.0, 0.0 0.0 0.0 ] } ] } ROUTE Clock.fraction_changed TO CubePath.set_fraction ROUTE CubePath.value_changed TO Cube.set_translation

  21. Animating Rotation #VRML V2.0 utf8 Group { children [ # Rotating cylinder DEF Column Transform { rotation 0.0 0.0 1.0 0.0 children Shape { appearance Appearance { material Material { } } geometry Cylinder { height 1.0 radius 0.2 } } },

  22. Animating Rotation # Animation clock DEF Clock TimeSensor { cycleInterval 4.0 loop TRUE }, # Animation path DEF ColumnPath OrientationInterpolator { key [ 0.0, 0.50, 1.0 ] keyValue [ 0.0 0.0 1.0 0.0, 0.0 0.0 1.0 3.14, 0.0 0.0 1.0 6.28 ] } ] }

  23. Animating Rotation ROUTE Clock.fraction_changed TO ColumnPath.set_fraction ROUTE ColumnPath.value_changed TO Column.set_rotation

  24. Animating Scale #VRML V2.0 utf8 Group { children [ # Pulsing ball DEF Ball Transform { children Shape { appearance Appearance { material Material { } } geometry Sphere { } } },

  25. Animating Scale # Animation clock DEF Clock TimeSensor { cycleInterval 2.0 loop TRUE }, # Animation path DEF BallPath PositionInterpolator { key [ 0.0, 0.20, 0.65, 1.0 ] keyValue [ 1.0 1.0 1.0, 1.5 1.5 1.5, 1.1 1.1 1.1, 1.0 1.0 1.0, ]

  26. Animating Scale } ] } ROUTE Clock.fraction_changed TO BallPath.set_fraction ROUTE BallPath.value_changed TO Ball.set_scale

  27. Animating Multiple Shapes using one Interpolator #VRML V2.0 utf8 Group { children [ # Moving box DEF Cube1 Transform { children DEF ACube Shape { appearance Appearance { material Material { } } geometry Box { size 1.0 1.0 1.0 } } },

  28. Animating Multiple Shapes using one Interpolator Transform { translation -2.0 0.0 0.0 children DEF Cube2 Transform { children USE ACube } }, Transform { translation 2.0 0.0 0.0 children DEF Cube3 Transform { children USE ACube } },

  29. Animating Multiple Shapes using one Interpolator # Animation clock DEF Clock TimeSensor { cycleInterval 4.0 loop TRUE }, # Animation path DEF CubePath PositionInterpolator { key [ 0.00, 0.11, 0.17, 0.22, 0.33, 0.44, 0.50, 0.55, 0.66, 0.77, 0.83, 0.88, 0.99 ]

  30. Animating Multiple Shapes using one Interpolator keyValue [ 0.0 0.0 0.0, 1.0 1.96 1.0, 1.5 2.21 1.5, 2.0 1.96 2.0, 3.0 0.0 3.0, 2.0 1.96 3.0, 1.5 2.21 3.0, 1.0 1.96 3.0, 0.0 0.0 3.0, 0.0 1.96 2.0, 0.0 2.21 1.5, 0.0 1.96 1.0, 0.0 0.0 0.0 ] } ] }

  31. Animating Multiple Shapes using one Interpolator ROUTE Clock.fraction_changed TO CubePath.set_fraction ROUTE CubePath.value_changed TO Cube1.set_translation ROUTE CubePath.value_changed TO Cube2.set_translation ROUTE CubePath.value_changed TO Cube3.set_translation

  32. Using Multiple Interpolators #VRML V2.0 utf8 Group { children [ # Three rotating bars DEF Bar1 Transform { children Shape { appearance DEF White Appearance { material Material { } } geometry Box { size 1.5 0.2 0.2 } } },

  33. Using Multiple Interpolators DEF Bar2 Transform { children Shape { appearance USE White geometry Box { size 0.2 1.5 0.2 } } }, DEF Bar3 Transform { children Shape { appearance USE White geometry Box { size 0.2 0.2 1.5 } } },

  34. Using Multiple Interpolators # Animation clock DEF Clock TimeSensor { cycleInterval 4.0 loop TRUE }, # Animation paths, one for each bar DEF BarPath1 OrientationInterpolator { key [ 0.0, 0.50, 1.0 ] keyValue [ 0.0 0.0 1.0 0.0, 0.0 0.0 1.0 3.14, 0.0 0.0 1.0 6.28 ] },

  35. Using Multiple Interpolators DEF BarPath2 OrientationInterpolator { key [ 0.0, 0.50, 1.0 ] keyValue [ 1.0 0.0 0.0 0.0, 1.0 0.0 0.0 3.14, 1.0 0.0 0.0 6.28 ] }, DEF BarPath3 OrientationInterpolator { key [ 0.0, 0.50, 1.0 ] keyValue [ 0.0 1.0 0.0 0.0, 0.0 1.0 0.0 3.14, 0.0 1.0 0.0 6.28 ]

  36. Using Multiple Interpolators } ] } ROUTE Clock.fraction_changed TO BarPath1.set_fraction ROUTE Clock.fraction_changed TO BarPath2.set_fraction ROUTE Clock.fraction_changed TO BarPath3.set_fraction ROUTE BarPath1.value_changed TO Bar1.set_rotation ROUTE BarPath2.value_changed TO Bar2.set_rotation ROUTE BarPath3.value_changed TO Bar3.set_rotation

  37. Using Multiple Time Sensors #VRML V2.0 utf8 Group { children [ # Stationary Sun Shape { appearance DEF White Appearance { material Material { } } geometry Sphere { } },

  38. Using Multiple Time Sensors # Several orbiting planets DEF Planet1 Transform { translation 2.0 0.0 0.0 center -2.0 0.0 0.0 children Shape { appearance USE White geometry Sphere { radius 0.2 } } }, DEF Planet2 Transform { translation 3.0 0.0 0.0 center -3.0 0.0 0.0 children Shape { appearance USE White geometry Sphere { radius 0.3 } } },

  39. Using Multiple Time Sensors DEF Planet3 Transform { translation 4.0 0.0 0.0 center -4.0 0.0 0.0 children Shape { appearance USE White geometry Sphere { radius 0.5 } } }, # Animation clocks, one per planet DEF Clock1 TimeSensor { cycleInterval 2.0 loop TRUE }, DEF Clock2 TimeSensor { cycleInterval 3.5 loop TRUE },

  40. Using Multiple Time Sensors DEF Clock3 TimeSensor { cycleInterval 5.0 loop TRUE }, # Animation paths, one per planet DEF PlanetPath1 OrientationInterpolator { key [ 0.0, 0.50, 1.0 ] keyValue [ 0.0 0.0 1.0 0.0, 0.0 0.0 1.0 3.14, 0.0 0.0 1.0 6.28 ] },

  41. Using Multiple Time Sensors DEF PlanetPath2 OrientationInterpolator { key [ 0.0, 0.50, 1.0 ] keyValue [ 0.0 0.0 1.0 0.0, 0.0 0.0 1.0 3.14, 0.0 0.0 1.0 6.28 ] }, DEF PlanetPath3 OrientationInterpolator { key [ 0.0, 0.50, 1.0 ] keyValue [ 0.0 0.0 1.0 0.0, 0.0 0.0 1.0 3.14, 0.0 0.0 1.0 6.28 ] } ] }

  42. Using Multiple Time Sensors ROUTE Clock1.fraction_changed TO PlanetPath1.set_fraction ROUTE Clock2.fraction_changed TO PlanetPath2.set_fraction ROUTE Clock3.fraction_changed TO PlanetPath3.set_fraction ROUTE PlanetPath1.value_changed TO Planet1.set_rotation ROUTE PlanetPath2.value_changed TO Planet2.set_rotation ROUTE PlanetPath3.value_changed TO Planet3.set_rotation

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