PROSEMINAR WEB3D

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PROSEMINAR WEB3D

• ANIMATIONS
• COLORS LIGHTING
• TEXTURES
• By Riff Roger

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Whats the Goal?
Get Objects to change move in a scene
Animations

Lightening up the scene,and describing
materials colors
Colors Lighting
Adding textures to your scene for realism
Textures
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Picturing view

• Cartoons

Scientific (molecule)
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Picturing view

• Our earlier animations didnt show moves, they
  were just static, here are some moving.
• http//www.animationcentral.com/symbols.htm

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I. Animations

• Def Changes in the virtual universe that are
  independant of the user action.
• ExTic Tac of our watch (happens without any
  interaction).
• To create animations,
• We use the behaviors classes
• Of the Java3D-API.

Java3D-API
Behaviors classes
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I.1.How to create Animations?
Dealing view positions Orientations in
Animations
Time-based Animations
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I.1.A.Time-based Animations
InterpolatorsAlpha Object
Time-based Animations

• The defined interpolator behaviors smoothly
  interpolates between two
• extreme values which are 0.0 and 1.0 which is
  called the alpha value
• (thats why the name interpolators).
• Alpha Value
• time (ms) is mapped to alpha value in range
  0,1.
• alpha value 0,1 is mapped onto predefined
  behavior.
• 0 is mapped to minimum extreme value .
• 1 to maximum extreme value.
• Alpha 1
• Value
• 0 1
  time

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Phases of the Alpha wave form
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Main steps to create a time-based animation
(thru an Ex. of ClockAnimation)

• public class ClockAnimation // using the
  RotationInterpolator
• public BranchGroup createSceneGraph( )
• // create the root of the Branch
• BranchGroup obj new BranchGroup( )
• // 1.create a Target object with the
  appropriate capability(here TransformGroup)
• TransformGroup target new
  TransformGroup( )
• target.setCapability(Tr
  ansformGroup.ALLOW_TRANSFORM_WRITE)
• // 2.create an Alpha object (here it rotates
  with a period of 1 min)
• Alpha alpha new Alpha (-1,6000)

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(follows here)

• // 3.create an Interpolator referencing the Alpha
  and the Target
• RotationInterpolator rot new
  RotationInterpolator (alpha,target)
• // 4.Add Scheduling bounds to the
  Interpolator
• rot.setSchedulingBounds(new
  BoundingSphere( ))
• // 5.Add the Interpolator to the scene graph
• obj.addChild(target)
• target.addChild(new Clock( ) )
• obj.addChild(rot)
• // let Java3D perform
• obj.compile( )
• return obj
• // end of createSceneGraph( )
• // end of ClockAnimation

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Output of the complete prog.

• ClockAnimation by 430

N.B the alpha effect stays up to the programmer,
hes the one to decide how to increase or
decrease it (Smoothing of the alphawaveform).
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Overviewing the API

• Interpolators Behaviors They are called
  interpolators because they smoothly interpolate
  between the two extreme values that an
  interpolator can produce.

(Fig. Interpolators classes Hierachy)
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Two Scenes showing various Interpolators with
their divergences.
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Overviewing the API

• Alpha Behaviors.
• Four General constructors
• 1.Alpha()constructs an alpha with
  modeINCREASING-ENABLE, loop count-1,
  increasing alpha duration1000,and all others
  parameters0,except Starttime.
• 2.Alpha (int loopcount,long increasingAlphaduratio
  n).
• 3.Alpha(int loopcount,long triggerTime,long
  increasingAlphaduration ....).
• 4.Alpha( with all the different parameters.....).

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I.1.B.Dealing View positions Orientations

• A.Billboard Classes
• Billboard refers to the technique of
  automaticallly rotating a planar visual object
  such it is always facing the viewer.
• Motivationtextured plane as a low cost
  replacement for the complex geometry.
• Classic example Trees as 2D Textures because
  they look the same when viewed in the back or
  front.

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Steps for creating a billboard object(same as
the interpolator object but no alpha object to
drive the animation)

• public BranchGroup createSceneGraph(SimpleUniverse
  su)
• BranchGroup objRoot new BranchGroup()
• Vector3f translate new Vector3f()
• Transform3D T3D new Transform3D()
• TransformGroup TGT new TransformGroup()
• //1.create a target TransformGroup with
  ALLOW_TRANSFORM_WRITE capability
• TransformGroup TGR new TransformGroup()
• Billboard billboard null
• BoundingSphere bSphere new BoundingSphere()

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(follows here)

• translate.set(new Point3f(1.0f, 1.0f, 0.0f))
• T3D.setTranslation(translate)
• TGT.set(T3D)
• // set up for billboard behavior
• TGR.setCapability(TransformGroup.ALLOW_TRANSFORM_W
  RITE) //1.step as above
• //2.create a Billboard referencing the Target
  Transformation
• billboard new Billboard(TGR)
• //3.supply ascheduling bound
• billboard.setSchedulingBounds(bSphere)
• //4. assemble scene graph
• objRoot.addChild(TGT)
• objRoot.addChild(billboard)

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TGT.addChild(TGR) TGR.addChild(createTree())

• Scene Graph

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Output
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Overview of Billboard API

• Four consructors
• Billboard()constructs a Billboard node with
  default
• parametersmodeROTATE_ABOUT_AXIS,axis(0,1,0).
• Billboard(TransformGroup tg)contructs a
• Billboard node with default parameters that
  operates on
• the specified TransformGroup node .
• Billboard(TransformGroup tg,int mode,Vector 3f
  axis)Thru
• a vector as axis, with a defined mode that
  operates on the defined TransformGroup node.
• Billboard(TransformGroup tg,int mode,Point 3f
  axis)Thru a point as axis.

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Some Billboard Methods
Billboard class

void setAlignementAxis(Vector3f axis)sets the
Alignement axis thru a vector. void
setAlignementAxis (float x,floty,float z) do the
same but thru a 3D axis. void setRotationpoint(Po
int3f point) void setRotationPoint(float x,float
y,float z) void setTarget(TaransformGroup tg)
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B.LOD (level of DetailAnimations)

• LOD is a general term for a technique that varies
  the amount of detail in a visual object based on
  some value from the virtual world.
• They are designed to provide increasingly
  detailed models as the user approaches
• The typical Example is to vary the LOD based on
  the distance to the viewer(sometimes on the
  rendering speed).

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LOD animation example(LOD snowflakes)

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Steps for Creating a LOD Object(same as the
Interpolator but no alpha value)

• public BranchGroup createSceneGraph()
• BranchGroup objRoot new BranchGroup()
• BoundingSphere bounds new BoundingSphere()
• // create target TransformGroup with Capabilities
• TransformGroup objMove new TransformGroup()
• //1. create DistanceLOD target object
• Switch targetSwitch new Switch()
• targetSwitch.setCapability(Switch.ALLOW_SWITCH_WRI
  TE)

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//6. add visual objects to the target switch
targetSwitch.addChild(new Sphere(.40f, 0, 25))
targetSwitch.addChild(new Sphere(.40f, 0, 15))
targetSwitch.addChild(new Sphere(.40f, 0, 10))
targetSwitch.addChild(new Sphere(.40f, 0, 4))

• // 2.create list of distances tresholds array for
  the distanceLod object
• float distances 5.0f, 10.0f, 20.0f
• //3.create DistanceLod object using that array
• DistanceLOD dLOD new DistanceLOD(distances,
  new Point3f())
• //4.Set the Target switch object for the distance
  LOD
• dLOD.addSwitch(targetSwitch)
• //5.supply ascheduling boundsfor the distance LOD
  Object
• dLOD.setSchedulingBounds(bounds)

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// 6.assemble scene graph objRoot.addChild(objMo
ve) objMove.addChild(dLOD) // make the bounds
move with object objMove.addChild(targetSwitch)
// must add switch to scene graphreturn
objRoot // end of CreateSceneGraph method of
DistanceLODApp

• Scene Graph...

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Output
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Overviewing the LOD API

• Constuctor LOD()constructs and initializes an
  LOD node.
• LOD methods summary

void addSwitch(Switch switchNode)Apppends the
specified switch Node to this LODs List of
switches. void insertSwitch(Switch node,int
index)inserts the specified switch node at the
specified index. int numSwitches() returns a
count of the LODs switch. void setSwitch(Switch
switchnode, int index)repalces the
specified Switch node with the switch node
provided.
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C.MORPH

• Interpolators classes change various visual
  attributes in the virtual,but theres no
  interpolators to change geometry of a visual
  object,thats what does the Morph class.
• Morph objects can be used to turn stuff into
  another that means to change any Geometry into
  another(pyramids into cubes, dogs into cats)
• To create Morph object, we should
• 1.create an array of Geometry Arrayobjects,
• 2.create a Morph object with ALOW_WEIGHTS_WRITE,
• 3. assemble the scene Graph.

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Example of a Morph Code

• public class MorphBehavior extends Behavior
• private Morph targetMorph
• private Alpha alpha
• // the following two members are here for
  efficiency
• private double weights 0, 0, 0, 0
• private WakeupCondition trigger new
  WakeupOnElapsedFrames(0)
• // create MorphBehavior
• MorphBehavior(Morph targetMorph, Alpha alpha)
• this.targetMorph targetMorph
• this.alpha alpha

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public void initialize()// set initial wakeup
conditionthis.wakeupOn(trigger)

• public void processStimulus(Enumeration
  criteria)
• // don't need to decode event since there is only
  one trigger
• weights0 0 weights1 0 weights2 0
  weights3 0
• float alphaValue 4f alpha.value() // get
  alpha
• int alphaIndex (int) alphaValue // which Geom
  obj
• weightsalphaIndex (double) alphaValue -
  (double)alphaIndex
• if(alphaIndex lt 3) // which other obj
• weightsalphaIndex 1 1.0 -
  weightsalphaIndex
• else weights0 1.0 - weightsalphaIndex

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targetMorph.setWeights(weights)
this.wakeupOn(trigger) // set next wakeup
condition // end of class MorphBehavior

• Fig-OUTPUT

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Overviewing the Morph API
Node

• Constructors
• Morph(GeometryArray geometryArrays)constructs
  and initializes a Morph object with specified
  arry and null appearance object
• Morph(GeometryArray geometryArrays,Appearance
  appearance)constructs and initializes a Morph
  object with specified arry and the defined
  appearance object

Morph
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Morph Method Summary

• void setApperance(Apearnce appearance) sets he
  appearance Component of the Morph node
• void setGeometryArrays(GeometryArray
  geometryArrays) sets the Geometry arrays
  Components of the Morph Node.
• void setWeights(double weights)sets this Morph
• Nodes morph weight vector.

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II.COLORS LIGHTING

• We have seen so far how to create time based
  and Billboard-Lod animations ,
• Now we think about coloring
• and lighting them.

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A.COLORS

• What is the Color?
• You can specify color in 3 places
• per-vertex geometry - has highest precedence .
• material - enables lighting. only used for lit
  objects .
• coloring attributes - only used for unlit objects
  when no material is specified.

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B.LIGHTING

• To obtain Lighting effect, one must
• add light objects to the scene graph .
• attach a material to the shape's appearance .
• add normals to shape's geometry.
• Shadows and inter-object reflection are not
  modeled (as seen in the picture B.1.).

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Picture B.1.
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Lights objects
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Directional light
Ambient Light (soft and general)

• Directional light

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Point light

• Point light

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Spot light

• Spot light

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Steps for Creating Lights(Thru the Teapotcode)

• public BranchGroup createSceneGraph()
• // Create the root of the branch graph
  BranchGroup
• objRoot new BranchGroup()
• ...
• // 1.Create Directional light with color and
  direction. Add it to scene.
• DirectionalLight light new DirectionalLight(new
  Color3f(1.f,1.f,1.f),new Vector3f(-1,-1,0))
  light.setCapability(Light.ALLOW_COLOR_WRITE)
  light.setInfluencingBounds(new BoundingSphere())
  objRoot.addChild(light)

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Following...

• //2. Create AmbientLight light with color. Add it
  to scene.
• AmbientLight ambientLight new AmbientLight(new
  Color3f(.3f,.3f,.3f)) ambientLight.setInfluencing
  Bounds(new BoundingSphere()) objRoot.addChild(amb
  ientLight)
• ...
• return objRoot

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Output

• Check it on
• This ouput helps us to see clearly the Lightening
  on a Teapot.
• http//www.willamette.edu/gorr/classes/cs445/lect
  ures/Java_Overview/demos/LightedTeapot/teapot.html
  

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IIITEXTURES

• You could model every detail of every 3D shape in
  your scene .
• This requires an enormous amount of modeling
  effort
• More shapes means more to draw and worse
  interactivity .
• Instead, create the illusion of detail
• Take a photograph of the "real thing" .
• Paste that photo onto simple 3D geometry .
• Increases realism without increasing the amount
  of geometry to draw .
• Not every aspect of texture mapping are
  availaible in Java3D, but the main one.

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• So,the detail that characterizes the surface
  color and texture of many objects is difficult to
  model simply using polygons.
• The brick shown below is an example. On the left
  is the 3D image.
• Texture coordinates
  Textured Object

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Code snippet for loading textures(Recipe)

• public BranchGroup createSceneGraph()
• // Create the root of the branch graph
• BranchGroup objRoot new BranchGroup()
• ...
• // Load in the Texture File
• TextureLoader loader new TextureLoader("brick.jp
  g",this)
• //Create Texture object
• Texture brick loader.getTexture()
• //Create Appearance Object
• Appearance appearance new Appearance()

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(follows here)-Rotating cube code

• // Create Appearance Attributes and give to
  Appearance.
• // TextureAttributes can be used for
  transforming texture (e.g. scaling)
• TextureAttributes ta new TextureAttributes()
  appearance.setTextureAttributes(ta)
• // Attach Texture object to Appearance object
  appearance.setTexture(brick)
• // Create Shape object and assign it the
  Appearance object. Sphere mySphere new
  Sphere(0.7f,Primitive.GENERATE_TEXTURE_COORDS,appe
  arance)
• ...
• return objRoot

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Texture modes
The Texture mode in TextureAttributes controls
how texture pixels affect shape color
. TCtexture color , SM Shape mode

• Textures can be combined with the "color" of the
  shape.

PaTa
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Explaining the terms.

• Prgb is the color of the pixel being texture
  mapped, as if no texture-mapping was to take
  place
• Pa is the alpha of the pixel being texture
  mapped, as if no texture-mapping was to take
  place
• Trgb is the texture color
• Ta is the texture alpha
• Brgb is the blend color
• Non-primed quantities denote before
• Primed quantities denote after

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Sum up

• After all this talk,we still need to got deep
  into the Java3D API to master and know how each
  method needs to be handled,
• Mean time, we have seen that animating objects
  requires to lighten them up as well and add some
  textures for more realism.
• To have a picturingview
• http//www.animation-central.com/symbols.htm