Transcript No Slide Title

INTRODUCTION TO JAVA 3D
Martin Čadík
Czech Technical University in Prague, Czech Republic
department of computer science
and engineering
Content
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Overview
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Scene graph
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Java 3D classes
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Simple application
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Describing objects
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Groups, transforms
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Behaviors, interpolators, picking
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Lighting, Sound
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What Is Java3D?
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API
– Applications or Applets
– “Write once, run anywhere”
platform independent (IBM AIX, HP-UX, Linux, SGI IRIX, Solaris/Sparc,
Windows)
• display environments
•
– higher level API
• objects instead of vertices
• content instead of rendering process
– scalable
– scene graph - based
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Java3D - Overview
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Java
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Applications
– JRE
– SDK
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– scientific visualization,
animation, web design,
simulations, virtual world
construction (CAVE), training,
games, design automation
Java 3D
– JRE
– SDK
– OpenGL
– DirectX
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Code examples in
distribution
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Java3D Scene Graph
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VirtualUniverse
–
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to contain all 3D data
typically one per application
SimpleUniverse
Locale object
View
– describes how to view 3D
content
– multiple views per universe
– View Platform (movable)
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Content Branch
– describes 3D content
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Java 3D Renderer
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Canvas 3D
– surface onto which a View renders
– one canvas per view
– there can be multiple canvases per app
while (true) {
Process input
if (exit request)break
Check for collisions
Perform behaviors
Start playing sounds
Traverse scene graph and render objects
}
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Java 3D Classes
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javax.media.j3d package
javax.media.j3d.VirtualUniverse (java.lang.Object)
Enumeration getAllLocales( )
javax.media.j3d.Locale
VirtualUniverse getVirtualUniverse( )
void addBranchGraph( Branchgroup branchGroup )
removeBranchGraph( Branchgroup branchGroup ) void
Enumeration getAllBranchGraphs( )
javax.media.j3d.SceneGraphObject
Capabilities (read/write transforms, geometry coords...)
javax.media.j3d.Node
javax.media.j3d.NodeComponent
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Java 3D Classes
javax.media.j3d.Node
– Shapes, Groups, Sounds, Lights, etc.
– parent node
– location (local, VWorld transform)
– bounding volume (automatical computation)
javax.media.j3d.NodeComponent
– attributes
– Shape geometry, Shape appearance, Shape texture, etc.
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javax.vecmath package
javax.vecmath.Tuple3d
Vector3d
Point3d, Color3d, etc.
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Coordinate System, Elements
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Coordinate system
– Right-handed
• +X is to the right
• +Y is up
• +Z is towards the viewer
– Angles in radians
– Distance in meters
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Elements in a Geometry
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–
–
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Coordinates
Normals
Colors
TextureCoordinates
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Simple Java3D Application
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Construct view branch
– Canvas3D
– SimpleUniverse
• VirtualUniverse, Locale,
BranchGroup, TransformGroup,
ViewPlatform, View
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Construct content branch
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–
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–
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BranchGroup
TransformGroup
Shape3D, Light, Sound...
Behavior
SimpleApp3D
– code
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Shape3D
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Fundamental mean of describing object
javax.media.j3d.Shape3D (Leaf)
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Geometry
void setGeometry(Geometry geometry)
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Appearance
void setAppearance(Appearance appearance)
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Geometry
javax.media.j3d.Geometry (NodeComponent)
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GeometryArray
– LineArray, PointArray, TriangleArray, QuadArray
– Indexed~
– Stripped versions
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Text3D
javax.media.j3d.Text3D
– example
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Raster
– raster image
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Appearance
javax.media.j3d.Appearance (NodeComponent)
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Specifies how to render Geometry sibling
– Color (intrinsic) and shading (flat, Gouraud)
• ColoringAttributes
• Material
– Transparency
• TransparencyAttributes
– Line, point, polygon attributes
• LineAttributes, PointAttributes,
PolygonAttributes
– Rendering control
– Texture mapping
– example
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Loading content
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Loader
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Available loaders
– creates scene graph elements
from a file
com.sun.j3d.loaders
– 3DS, COB, DEM, DXF, IOB,
LWS, NFF, OBJ, PDB, PLAY,
SLD, VRT, VTK, WRL
– only the interface included in
Java 3D
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Usage
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–
–
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import loader
create loader object
Scene variable
load file
insert Scene into the scene
graph
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Grouping
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exactly one parent, arbitrary children
javax.media.j3d.Group (Node)
BranchGroup, OrderedGroup, SharedGroup (Link),
Switch, TransformGroup
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child rendering order determines Java 3D
– can perform sorting for better rendering efficiency
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BranchGroups
– can be attached to Locale --> it makes it live --> constrains by
capabilities
– can be compiled
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Transforming
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world coordinate system
TransformGroup
– new coordinate system relative to parent
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transformation accumulate as graph is traversed
Transform3D (Object)
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4 x 4 matrix of doubles - Matrix4d
translate, rotate, scale, shear
must be affine (no perspective)
helper methods
• setIdentity, rotX.., setScale, setTranslation, setRotation, etc.
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Texture mapping
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Appearance node
Texture2D (abstract Texture (NodeComponent))
- image textures, example
Texture3D - volume textures
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Texture format
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– Intensity
– Luminance, Alpha
– RGB, RGBA
TextureAttributes (NodeComponent)
– Mode: Blend, Decal, Modulate, Replace
– Transform
– Perspective correction
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Behaviors
javax.media.j3d.Behavior
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code to run (processStimulus)
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wakeup conditions
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frame or milliseconds have elapsed
AWT event
transform change
collision, view platform or sensor is close
scheduling bounds
– activation radius intersects scheduling bounds
– runs only when necessary
– common error - forgetting scheduling bounds
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Interpolators
javax.media.j3d.Interpolator
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simple behaviors
– vary a parameter from starting to ending value
– Time-to-Alpha mapping (Alpha (Object) <0,1>)
– Alpha-to-Value mapping
• transforms, colors, switches
– Target (f.e. TransformGroup)
PositionInterpolator,
RotationInterpolator,
ColorInterpolatorm, etc.
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Input devices
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joysticks
6DOF devices (Magellan, Ultrasonic tracker...)
buttons
real / virtual
javax.media.j3d.InputDevice interface
– implementation maps physical detectors onto
(process input, return Sensor)
Sensor
object
javax.media.j3d.Sensor (Object)
– SensorRead
object
• time-stamp
• 6DOF value, button state
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Picking features
– selecting Shapes
– interaction methods
– designed for speed (Bounds)
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Pick methods (Node)
– take PickShape (PickPoint, PickRay, PickSegment)
– return SceneGraph objects
– f.e.: pickAll, pickAllSorted, pickClosest
– example
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Lighting the environment
javax.media.j3d.Light
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Light attributes
– on/off
– color
– bounding volume and scope
Types of lights
– ambient - AmbientLight
– directional - DirectionalLight
– point - PointLight
• by default universal scope
– again: common error - forgetting
scheduling bounds
• attenuation
– spot - SpotLight
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Sounds
javax.media.j3d.Sound
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Sound properties
– sound data
Sounds
• AIF, AU, WAV
– triggered
– continuous
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(MediaContainer)
– looping parameters
– playback priority
– scheduling bounds
Sound types
– background - BackgroundSound
– point - PointSound
• attenuated
– cone - ConeSound
• attenuated
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Misc
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Background
javax.media.j3d.Background
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Fog
– exponential, linear
javax.media.j3d.Fog
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Acceleration
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Performance Guide
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capability bits
compilation
bounds, activation radius
geometry by reference
unordered rendering
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News
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FastScript 3D
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–
–
open source
web applets using Java3D via JavaScript and HTML
Java, Java3D required
fs.jar
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Java 3D
Thank you
for your attention
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