Computer Graphics with OpenGL, 4th Edition

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Computer Graphics with OpenGL, 4th Edition
Pearson education limited Edinburgh gate Harlow Essex CM20 2JE England and associated Companies throughout the world VisitusontheWorldWideWebat:www.pearsoned.co.uk c Pearson education Limited 2014 All rights reserved. no part of this publication may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photoco pying recording or otherwise, without either the prior written permission of the publisher or a licence permitting restricted copying in the United Kingdom ssued by the Copyright Licensing Agency Ltd, saffron House, 6-10 Kirby Street, London EClN 8TS All trademarks used herein are the property of their respective owners. The use of any trademark in this text does not vest in the author or publisher any trademark ownership rights in such trademarks, nor does the use of such trademarks imply any affiliation with or endorsement of this book by such owners. PEARSON ISBN 10: 1-292-02425-4 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library Printed in the united states of america PEA O N CU ST M ABRAR Y Table of contents Computer Graphics Hardware Donald D. hearn/m. pauline baker Warren carithers Computer graphics hardware Color plates Donald d. hearn/M. Pauline baker Warren Carithers 27 2. Computer Graphics Software Donald d. hearn/M. Pauline baker. Warren carithers 29 3. Graphics Output Primitives Donald d. hearn/M. Pauline baker. Warren Carithers 45 4. Attributes of Graphics Primitives Donald d. Hearn/M. Pauline baker. Warren Carithers 99 5 Implementation Algorithms for Graphics Primitives and Attributes Donald d, hearn/m. pauline baker. Warren carithers 131 6. Two-Dimensional Geometric Transformations Donald D. Hearn/M. Pauline baker. Warren Carithers 189 7. Two-Dimensional Viewing Donald D. Hearn/M. Pauline baker. Warren Carithers 227 8. Three-Dimensional Geometric Transformations Donald D. Hearn/M. Pauline baker. Warren Carithers 273 9. Three-Dimensional viewing Donald D. Hearn/M. Pauline Baker. Warren Carithers 301 Three-Dimensional viewing Color Plate Donald d, hearn/m. pauline baker Warren carithers 353 0. Hierarchical Modeling Donald d. hearn/M. pauline baker. Warren Carithers 355 I Computer Animation Donald d. hearn/m. pauline baker. Warren carithers 365 2. Three-Dimensional Object Representations Donald d. hearn/m. pauline baker. Warren carithers 389 Three-Dimensional object Representations Color plate Donald d. hearn/M. pauline baker. Warren carithers 407 13. Spline Representations Donald D. Hearn/M. Pauline baker. Warren Carithers 409 4. Visible-Surface Detection Method Donald d. hearn/m. pauline baker. Warren Carithers 465 15. Illumination Models and Surface-Rendering Methods Donald d. hearn/m. pauline baker Warren carithers 493 Illumination Models and Surface-Rendering Methods Color Plates Donald d. hearn/m. pauline baker. Warren carithers 541 6. Texturing and Surface-Detail Methods Donald d. hearn/m. pauline baker Warren carithers 543 Texturing and Surface-Detail Methods Color plates Donald d. hearn/M. Pauline baker Warren Carithers 567 7. Color Models and Color Applications Donald d. hearn/m. pauline baker warren carithers 569 Color Models and Color Applications Color Plate Donald d. hearn/M. pauline baker. Warren carithers 589 8. Interactive Input Methods and Graphical User Interfaces Donald d. hearn/M. Pauline baker. Warren Carithers 591 Interactive Input Methods and Graphical User Interfaces Color Plates Donald d. hearn/m. pauline baker Warren carithers 631 9. Globa‖ amination Donald d. hearn/m. pauline baker Warren carithers 633 Global lllumination Color plates Donald d. hearn/m. pauline baker. Warren carithers 659 20. Programmable Shaders Donald d. hearn/M. Pauline baker. Warren Carithers 663 Programmable Shaders Color Plates Donald d. hearn/m. pauline baker. Warren carithers 693 21. Algorithmic Modeling Donald d. hearn /M. Pauline baker. Warren Carithers 695 Algorithmic Modeling Color Plates Donald d. hearn/M. Pauline baker. Warren Carithers 725 22. Visualization of Data Sets Donald d. hearn/m. pauline baker. Warren carithers 729 Visualization of data sets color plates Donald d. hearn/m. pauline baker Warren carithers 735 Appendix: Mathematics for Computer Graphics Donald d. Hearn/M. Pauline baker. Warren carithers 737 Appendix: Graphics File Formats Donald d. hearn/M. Pauline baker Warren carithers 773 Bbi。 graphy Donald D. Hearn/M. Pauline baker. Warren Carithers 789 Index 801 This page intentionally left blank Computer Graphics Hardware 1 Video Display Devices 2 Raster-Scan Systems 3 Graphics Workstations and Viewing Systems 4 Input Devices 5 Hard-Copy Devices 6 Graphics Networks 7 Graphics on the Internet 8 Summary phics is wide nized, and a broad range of graphics hardware and soft- ware systems is now available for applications in virtually all fields. Graphics capabilities for both two-dimensional and three dimensional applications are now common, even on general-purpose computers and handheld calculators With personal computers, we can use a variety of interactive input devices and graphics software packages For higher-quality applications, we can choose from a num ber of sophisticated special-purpose graphics hardware systems and technologies. In this chapter, we explore the basic features of graphics hardware components and graphics software packages From Chapter 2 of Computer Graphics with Opengl, Fourth Edition, Donald Hearn, M. Pauline Baker, Warren R Carithers Copyright o 2011 by Pearson Education, Inc. Published by Pearson Prentice Hall. All rights reserved Computer graphics Hardware 1 Video Display Devices Typically, the primary output device in a graphics system is a video monitor. Historically, the operation of most video monitors was based on the standard cathode-ray tube(Crt) design, but several other technologies exist. In recent years, flat-panel displays have become significantly more popular due to their reduced power consumption and thinner designs Refresh Cathode-Ray Tubes Figure 1 illustrates the basic operation of a CRT. a beam of electrons(cathode rays), emitted by an electron gun, passes through focusing and deflection systems that direct the beam toward specified positions on the phosphor-coated screen The phosphor then emits a small spot of light at each position contacted by the electron beam. Because the light emitted by the phosphor fades very rapidly, some method is needed for maintaining the screen picture. One way to do this is to store the picture information as a charge distribution within the crt. this charge distribution can then be used to keep the phosphors activated However the most common method now employed for maintaining phosphor glow is to redraw the picture repeatedly by quickly directing the electron beam back over the same screen points. This type of display is called a refresh CRt, and the frequency t which a picture is redrawn on the screen is referred to as the refresh rate The primary components of an electron gun in a CRT are the heated metal cathode and a control grid(Fig. 2). Heat is supplied to the cathode by directing a current through a coil of wire, called the filament, inside the cylindrical cathode structure. This causes electrons to be boiled off"the hot cathode surface. In Magnetic Deflection Coils Phosphor Focusing Coated System Screen B Electron Connector Ele FIGURE 1 Beam Ins Basic design of a magnetic-deflection Electron Bcam Path Heater ng Filament Control Accelerating Operation of an electron gun with an accelerating anode Computer graphics hardware the vacuum inside the CrT envelope, the free, negatively charged electrons are hen accelerated toward the phosphor coating by a high positive voltage. The accelerating voltage can be generated with a positively charged metal coating on the inside of the CRT envelope near the phosphor screen, or an accelerating anode, as in Figure 2, can be used to provide the positive voltage. Sometimes the electron gun is designed so that the accelerating anode and focusing system are within the same unit Intensity of the electron beam is controlled by the voltage at the control grid which is a metal cylinder that fits over the cathode. A high negative voltage applied to the control grid will shut off the beam by repelling electrons and stopping them from passing through the small hole at the end of the control- grid structure. A smaller negative voltage on the control grid simply decreases the number of electrons passing through. Since the amount of light emitted by the phosphor coating depends on the number of electrons striking the screen, the brightness of a display point is controlled by varying the voltage on the control grid. This brightness, or intensity level, is specified for individual screen positions with graphics software commands The focusing system in a Crt forces the electron beam to converge to a small cross section as it strikes the phosphor. Otherwise the electrons would repel each other, and the beam would spread out as it approaches the screen Focusing is accomplished with cither electric or magnctic ficlds. With electrostatic focusing, the electron beam is passed through a positively charged metal cylinder so that electrons along the center line of the cylinder are in an equilibrium position. This arrangement forms an electrostatic lens as shown in Figure 2, and the electron beam is focused at the center of the screen in the same way that an optical lens ocuses a beam of light at a particular focal distance. Similar lens focusing effects can be accomplished with a magnetic field set up by a coil mounted around the outside of the CrT envelope, and magnctic lens focusing usually produces the smallest spot size on the screen Additional focusing hardware is used in high-precision systems to keep the beam in focus at all screen positions. The distance that the electron beam must travel to different points on the screen varies because the radius of curvature for most CRTs is greater than the distance from the focusing system to the screen center. Therefore, the clectron beam will be focused properly only at the center of the screen. As the beam moves to the outer edges of the screen, displayed images become blurred. To compensate for this, the system can adjust the focusing according to the screen position of the beam As with focusing, deflection of the electron beam can be controlled with either electric or magnetic fields. Cathode-ray tubes are now commonly constructed with magnetic-deflection coils mounted on the outside of the Crt envelope, as lustrated in Figure 1. Two pairs of coils are used for this purpose. One pair is mounted on the top and bottom of the Crt neck and the other pair is mounted on opposite sides of the neck. The magnetic field produced by each pair of coils results in a transverse deflection force that is perpendicular to both the direction of the magnetic field and the direction of travel of the electron beam. horizontal deflection is accomplished with one pair of coils, and vertical deflection with the other pair. The proper deflection amounts are attained by adjusting the current through the coils. When electrostatic deflection is used, two pairs of parallel plates are mounted inside the crt envelope. One pair of plates is mounted horizontally to control vertical deflection and the other pair is mounted vertically to control horizontal deflection(Fig 3) Spots of light are produced on the screen by the transfer of the Crt beam energy to the phosphor. When the electrons in the beam collide with the phosphor 【实例截图】
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