Graphics

cgvr.korea.ac.kr Graphics Lab @ Korea University

Lighting, Fogging, Alpha Blending & Progressive

MeshesByeong-Seon Jeong

2002.1.22

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Contents

Lighting Fogging Alpha Blending Progressive Meshes Demo

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Lighting

Ambient Light is effectively everywhere in a scene a general level of light that fills an entire scene has no position or direction, only color and intensity

Direct Light Point

give off light equally in all directions have color and position within a scene, but no single direction

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Lighting(directional)

Directional emit parallel light have only color and direction, not position a light source at near infinite distance, such as the sun

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Lighting(spot)

Spot is made up of a bright inner cone and a larger outer cone have color, position, and direction in which they emit light

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Lighting(global illumination)

Global Illumination Formula

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Lighting(ambient)

Lighting Model Ambient

provides constant lighting for a scene lights all object vertices the same Formula

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Lighting(ambient)

Scene

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Lighting(ambient)

Source Code

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Lighting(diffuse)

Diffuse comes from one direction is scattered equally in all directions once it hits a surface Formula

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Lighting(diffuse)

Attenuation Factor

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Lighting(diffuse)

Spotlight Factor

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Lighting(diffuse)

Scene

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Lighting(diffuse)

Source Code

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Lighting(specular)

Specular comes from a particular direction tends to bounce off the surface in a preferred direction Shiny metal, plastic Formula

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Lighting(specular)

Scene

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Lighting(specular)

Source Code

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Lighting(emissive)

Emissive is emitted by an object Glow Formula

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Lighting(emissive)

Scene

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Lighting(emissive)

Source Code

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Fogging

Fogging Adding fog to a 3-D scene can enhance realism provide ambiance or set a mood, and obscure artifacts Formula

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Fogging(factors)

Factors Linear

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Fogging(factors)

Exp

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Fogging(factors)

Exp2

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Fogging(graph)

The Illumination graph of the formula

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Fogging(scene)

Scene

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Fogging(source code)

Source code

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Alpha Blending

Alpha Blending combines the color value of the processed polygon pixel

with the pixel already stored in the frame buffer Formula

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Alpha Blending(scene)

Scene

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Alpha Blending(source code)

Source Code

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Progressive Meshes

Progressive Meshes A progressive mesh is one in which the vertex information

is stored internally in a special tree that can be accessed to render the mesh with any number of vertices.

This procedure is fast, so progressive meshes are ideal for level-of-detail scenarios, where objects in the distance are rendered with fewer polygons.

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Progressive Meshes(diagram)

Progressive Mesh Flow Diagram

Graphic files

Ex. *.3DS, *.ASE etc Dynamic LOD

User inputEx: Distance

*.X file load

Material & Texturesetup

Progressive Meshcreation

Progressive MeshLevel Control

Rendering

Initialization Update frame

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Progressive Meshes(scene)

Scene

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Demo