3D Objects

Subject : T0934 / Multimedia Programming FoundationSession : 12Tahun : 2009Versi : 1/0

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Learning Outcomes

In the end of this session, students must be able to: – Understand the basic principal

of 3D objects

Outline

• 3D Coordinates systems• 3D Models• 3D Transformation• 3D Rendering• Java 3D API

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Coordinate Systems

• Use x,y,z coordinates to represent a 3D object width, height, and length

• Left-handed coordinate system x positive to the right

• Right-handed coordinate system (default for Java) x positive to the left or z positive toward the viewer

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YY

XX

ZZYY

XX

ZZYY

XX

ZZ

Object Coordinates

• Geometric center the point in object where x,y, and z are all zero in values, usually located inside the object.

• Object coordinates start from its geometric center

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YY

XX

ZZ

World Coordinates

• Coordinates that shows how the objects are located in relation to the 3D world they are in

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ZZ

YY

3D Model

• Vertices (Vertex for singular) corner points of an object

• Edges lines which connect the vertices

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Vertex

Edge

Hidden line

Surface/face

Hidden surface

3D Polygon

• A closed figure created by three or more vertices connected with edges

• Simplest polygon triangle• Complex 3D shapes can be decomposed

into a collection of triangles, commonly called a mesh

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Displaying 3D Model

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commonly called "eye space" or "camera space”. Objects are converted to view space to know what is visible on the screen.

project the view coordinates into 2D coordinates that map directly to viewport (window or rectangle which limits the visibility of 3D world).

3D Transformation

• Position (translation)• Size (scaling)• Orientation (rotation)• Shapes (shear)

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x’

y’

z’

1

1 0 0 tx

0 1 0 ty

0 0 1 tz

0 0 0 1

x

y

z

1

= *

XX

ZZ

tt

Rendering

• Process of converting the 3D model into an on-screen 2D image

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3D Rendering Techniques

• Flat shading• Lambert shading• Gouraud shading• Phong shading• Texture mapping• Bump mapping• Cel shading• Raytracing• Radiosity• And so on …

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Scene Graph

• Maintains information about all entities in the 3D world in structures called nodes

• Group nodes contain information about themselves and point to other nodes (descendants)

• Leaf nodes contain only information about themselves and have no children

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Scene Graph

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SceneScene

TerrainTerrain

Player1Player1 Player2Player2

Java 3D API

• Enables the creation of three-dimensional graphics applications and Internet-based 3D applets.

• Provides high-level constructs for creating and manipulation 3D geometry and building the structures used in rendering that geometry.

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Sample Code

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Create 3D canvas

Create The 3D World

Sample Code

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Create Background The 3D World

Sample Code

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Prepare color for the ball

Prepare The Texture for the ball

Sample Code

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Prepare appearance for the ball by including The color and Texture

Create The ball

Sample Code

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Prepare PointLight for lightning effect

Sample Code

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Adding component to The Universe

Sample Code

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Setting action for application

Sample Code

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Rotate The Ball

Result

References

• Java 3D API Tutorial. 2009. http://java.sun.com/developer/onlineTraining/java3d/

• 3D Game Programming All in One. Finney, Kenneth C. 2004. Ch 3.

• 3D Basic. 1999. http://www.gamedev.net/reference/articles/article673.asp

• Graphics Pipeline. 2000. http://www.arch.ttu.edu/visualization/5347-Digital_VIZ/VideoLectures/PptLecturePdfs/GraphicsPipelineAlgorithmic_12sep08.pdf

• Java 3D Tutorial. 2001. http://www.java3d.org/tutorial.htm• Combining Rotation and Translation in Java 3d. 2009.

http://www.developer.com/java/other/article.php/3712226• Creating a 3D Universe with Java3D. 1998.

http://www.acm.org/crossroads/xrds5-2/ovp52.html

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