OpenGL Programming Guide Second Edition - Niksula

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guide. Finally, an extensive Glossary defines the key terms used in this guide. What’s New in This Edition To the question, "What’s new in this edition?" the wiseacre answer is "About 100 pages." The more informative answer follows. Detailed information about the following new features of OpenGL Version 1.1 has been added. − Vertex arrays − Texturing enhancements, including texture objects (including residency and prioritization), internal texture image format, texture subimages, texture proxies, and copying textures from frame buffer data − Polygon offset − Logical operation in RGBA mode Program examples have been converted to Mark Kilgard’s GLUT, which stands for Graphics Library Utility Toolkit. GLUT is an increasingly popular windowing toolkit, which is well−documented and has been ported to different window systems. More detail about some topics that were in the first edition, especially coverage of the OpenGL Utility (GLU) Library. − An entire chapter on GLU tessellators and quadrics − A section (in Chapter 3) on the use of gluProject() and gluUnProject(), which mimics or reverses the operations of the geometric processing pipeline (This has been the subject of frequent discussions on the Internet newsgroup on OpenGL, comp.graphics.api.opengl.) − Expanded coverage (and more diagrams) about images − Changes to GLU NURBS properties − Error handling and vendor−specific extensions to OpenGL − Appendix C expanded to include OpenGL interfaces to several window/operating systems The first edition’s appendix on the OpenGL Utility Library was removed, and its information has been integrated into other chapters. A much larger and more informative index Bug fixes and minor topic reordering. Moving the display list chapter is the most noticeable change. What You Should Know Before Reading This Guide This guide assumes only that you know how to program in the C language and that you have some background in mathematics (geometry, trigonometry, linear algebra, calculus, and differential OpenGL Programming Guide − About This Guide − 3
geometry). Even if you have little or no experience with computer−graphics technology, you should be able to follow most of the discussions in this book. Of course, computer graphics is a huge subject, so you may want to enrich your learning experience with supplemental reading. Computer Graphics: Principles and Practice by James D. Foley, Andries van Dam, Steven K. Feiner, and John F. Hughes (Reading, MA: Addison−Wesley, 1990)⎯This book is an encyclopedic treatment of the subject of computer graphics. It includes a wealth of information but is probably best read after you have some experience with the subject. 3D Computer Graphics: A User’s Guide for Artists and Designers by Andrew S. Glassner (New York: Design Press, 1989)⎯This book is a nontechnical, gentle introduction to computer graphics. It focuses on the visual effects that can be achieved rather than on the techniques needed to achieve them. Once you begin programming with OpenGL, you might want to obtain the OpenGL Reference Manual by the OpenGL Architecture Review Board (Reading, MA: Addison−Wesley Developers Press, 1996), which is designed as a companion volume to this guide. The Reference Manual provides a technical view of how OpenGL operates on data that describes a geometric object or an image to produce an image on the screen. It also contains full descriptions of each set of related OpenGL commands⎯the parameters used by the commands, the default values for those parameters, and what the commands accomplish. Many OpenGL implementations have this same material on−line, in the form of man pages or other help documents, and it’s probably more up−to−date. There is also a http version on the World Wide Web; consult Silicon Graphics OpenGL Web Site (http://www.sgi.com/Technology/openGL) for the latest pointer. OpenGL is really a hardware−independent specification of a programming interface, and you use a particular implementation of it on a particular kind of hardware. This guide explains how to program with any OpenGL implementation. However, since implementations may vary slightly⎯in performance and in providing additional, optional features, for example⎯you might want to investigate whether supplementary documentation is available for the particular implementation you’re using. In addition, you might have OpenGL−related utilities, toolkits, programming and debugging support, widgets, sample programs, and demos available to you with your system. How to Obtain the Sample Code This guide contains many sample programs to illustrate the use of particular OpenGL programming techniques. These programs make use of Mark Kilgard’s OpenGL Utility Toolkit (GLUT). GLUT is documented in OpenGL Programming for the X Window System by Mark Kilgard (Reading, MA: Addison−Wesley Developers Press, 1996). The section "OpenGL−Related Libraries" in Chapter 1 and Appendix D gives more information about using GLUT. If you have access to the Internet, you can obtain the source code for both the sample programs and GLUT for free via anonymous ftp (file−transfer protocol). For the source code examples found in this book, grab this file: ftp://sgigate.sgi.com/pub/opengl/opengl1_1.tar.Z The files you receive are compressed tar archives. To uncompress and extract the files, type uncompress opengl1_1.tar OpenGL Programming Guide − About This Guide − 4
Page 1 and 2: OpenGL Programming Guide Second Edi
Page 3 and 4: Examples of Composing Several Trans
Page 5 and 6: Bitmaps and Fonts The Current Raste
Page 7 and 8: Chapter 12 Evaluators and NURBS Pre
Page 9 and 10: Implementation−Dependent Pixel De
Page 11 and 12: Rotation Perspective Projection Ort
Page 13 and 14: depth−cuing diffuse directional l
Page 15 and 16: RGBA mode server shading shininess
Page 17 and 18: To Tom Doeppner and Andy van Dam, w
Page 19: textures onto three−dimensional o
Page 23 and 24: Acknowledgments The second edition
Page 25 and 26: Chapter 1 Introduction to OpenGL Ch
Page 27 and 28: of motion. "Plate 8" shows the scen
Page 29 and 30: } glVertex3f (0.25, 0.75, 0.0); glE
Page 31 and 32: OpenGL as a State Machine OpenGL is
Page 33 and 34: is enabled and the primitive is a p
Page 35 and 36: If you are directly accessing a win
Page 37 and 38: glVertex3f (0.75, 0.75, 0.0); glVer
Page 39 and 40: human eye is only so good. The key
Page 41 and 42: Figure 1−3 Double−Buffered Rota
Page 43 and 44: Chapter 2 State Management and Draw
Page 45 and 46: appropriate size and location for a
Page 47 and 48: Chapter 5 for details on these topi
Page 49 and 50: Example 2−1 Reshape Callback Func
Page 51 and 52: See Figure 2−3 for some examples
Page 53 and 54: glVertex4f(2.3, 1.0, −2.2, 2.0);
Page 55 and 56: GL_LINES Draws a series of unconnec
Page 57 and 58: ones in blue, despite the extra col
Page 59 and 60: void glLineWidth(GLfloat width); Se
Page 61 and 62: void display(void) { int i; glClear
Page 63 and 64: GL_FILL to indicate whether the pol
Page 65 and 66: Figure 2−10 Constructing a Polygo
Page 67 and 68: 0xAA, 0xAA, 0xAA, 0xAA, 0x55, 0x55,
Page 69 and 70: glPolygonMode(GL_FRONT_AND_BACK, GL
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Figure 2−14 Six Sides; Eight Shar
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void glEdgeFlagPointer(GLsizei stri
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glEnableClientState (GL_VERTEX_ARRA
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process as few as eight vertices. (
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} else glColorPointer(sc, tc, str,
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GL_ALL_ATTRIB_BITS −− GL_COLOR_
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glBegin(GL_LINE_STRIP); for (i = 0;
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} out[0] = v1[1]*v2[2] − v1[2]*v2
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} } for (i = 0; i < 3; i++) { } v12
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Chapter 3 Viewing Chapter Objective
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the following. 1. Set up your tripo
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program, not necessarily the order
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} glViewport (0, 0, (GLsizei) w, (G
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interior spaces look when viewed fr
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Philosophy" in Chapter 7.) (OpenGL
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x−axis), if you want the object t
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shown in Figure 3−6. Figure 3−6
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glLoadIdentity(); glScalef(1.5, 0.5
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Figure 3−10 Separating the Viewpo
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Figure 3−12 Using gluLookAt() So,
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glMatrixMode(GL_PROJECTION); glLoad
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GLdouble near, GLdouble far); Creat
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planes and locate them wherever you
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(Chapter 10 discusses the depth buf
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{ } double radtheta, degtheta; radt
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Figure 3−21 Pushing and Popping t
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Advanced If you know enough mathema
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* clip left half −− x < 0 */ }
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#include #include #include stati
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Figure 3−25 Robot Arm You can use
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} } case ‘S’: shoulder = (shoul
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#include #include #include #incl
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Chapter 4 Color Chapter Objectives
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is called the color buffer. The siz
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number of bitplanes, 0.0 specifies
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Figure 4−4 A Color Map A painter
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mode. Then you must control the vis
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GL_FLAT. With flat shading, the col
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independent quad 4i Table 4−2 How
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"Real−World and OpenGL Lighting"
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desire a more accurate (or just dif
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Example 5−1 accomplishes these ta
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Example 5−1, the only element of
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GLfloat light_ambient[] = { 0.0, 0.
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Figure 5−2 GL_SPOT_CUTOFF Paramet
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A light position that remains fixed
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*/ void display(void) { } GLfloat p
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} gluLookAt (ex, ey, ez, 0.0, 0.0,
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it doesn’t matter what the back
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glMaterialfv(GL_FRONT_AND_BACK, GL_
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glTranslatef (1.25, 3.0, 0.0); glMa
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void display(void) { } glClear(GL_C
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colors when in RGBA mode. (See "The
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The diffuse term needs to take into
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of using this color ramp with a sin
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drawn in a window on the screen? Wh
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To blend three different images equ
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#include static int leftFirst = GL
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already in the framebuffer (the des
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} glPushMatrix (); glTranslatef (0.
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Figure 6−2 Aliased and Antialiase
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#include static float rotAngle = 0
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} glutDisplayFunc (display); glutMa
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} } rotAngle += 20.; if (rotAngle >
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#include #include #include #incl
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{ } switch (key) { } case ‘t’:
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} } glFogf (GL_FOG_DENSITY, 0.35);
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In these three equations, z is the
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} glFogf (GL_FOG_START, 1.0); glFog
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where m is the maximum depth slope
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Chapter 7 Display Lists Chapter Obj
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} } } } glEnd(); glVertex3f(x, y, z
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glEnd() calls are stored in the dis
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implementation may be able to perfo
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} return 0; The glTranslatef() rout
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arrays, so these operations can be
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mechanism requires that you put the
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} CP; int type; CP Adata[] = { }; {
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} glTranslatef(10.0, 30.0, 0.0); pr
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glEndList(); If you use the display
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Chapter 8 Drawing Pixels, Bitmaps,
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0xff, 0x00, 0xff, 0x00, 0xc0, 0x00,
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Drawing the Bitmap Once you’ve se
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an offset to every entry in the str
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{0x00, 0x00, 0x7e, 0xe7, 0xc3, 0xc3
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} glutMainLoop(); return 0; Images
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component, followed by a blue color
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current drawing buffers with glDraw
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Figure 8−8 glCopyTexImage*() and
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Figure 8−9 *SKIP_ROWS, *SKIP_PIXE
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Pixel Mapping All the color compone
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} int i, j, c; for (i = 0; i < chec
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} glutMotionFunc(motion); glutMainL
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3. Each component (R, G, B, A, or d
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5. If the storage format is one of
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lend a texture color with the surfa
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An Overview and an Example This sec
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#define checkImageHeight 64 static
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} init(); glutDisplayFunc(display);
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texture of internal format GL_R3_G3
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Note: There is one major limitation
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{ } switch (key) { } case ‘s’:
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GL_READ_BUFFER and are processed ex
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#include #include #include GLuby
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} glTexEnvf(GL_TEXTURE_ENV, GL_TEXT
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Figure 9−5 Texture Magnification
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eturned in textureNames do not have
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} GL_NEAREST); glTexParameteri(GL_T
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texture objects. void glPrioritizeT
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lended with the texture color in a
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the surface, the more distortion of
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Figure 9−8 Clamping a Texture You
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Initially in Example 9−6, equally
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} glFlush(); void reshape(int w, in
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calculated only at the time they’
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indexed by s’/q’ and t’/q’
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Figure 10−1 Region Occupied by a
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you might use them for saving an im
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can be one of the following: GL_FRO
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7. Logical operation Each of these
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You can obtain the values for all s
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} glPushMatrix(); glRotatef (90.0,
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pixel appears, it’s drawn only if
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Table 10−4 Sixteen Logical Operat
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} xwsize = right − left; ywsize =
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} glutSolidSphere (1.0, 16, 16); gl
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} glFlush(); void reshape(int w, in
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Example 10−5 Depth−of−Field E
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} } glAccum (GL_RETURN, 1.0); glFlu
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Chapter 11 Tessellators and Quadric
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hurts to be tidy. Tessellation Call
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void errorCallback(GLenum errorCode
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GLdouble value); For the tessellati
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The winding rules are also designed
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for several vertices may not get th
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The GLU provides a routine for obta
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GLUquadricObj* gluNewQuadric (void)
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sweepAngle are measured in degrees,
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} glTranslatef(0.0, 2.0, 0.0); glPu
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Chapter 12 Evaluators and NURBS Cha
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vertices can be used like any other
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} A cubic Bézier curve is describe
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You can use glEvalCoord1() with any
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}; {0.5, −1.5, −1.0}, {1.5, −
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Figure 12−3 Lit, Shaded Bézier S
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} for (i = 0; i < imageWidth; i++)
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once with the control points (ratio
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} glRotatef(330.0, 1.,0.,0.); glSca
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The default value for GLU_DISPLAY_M
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points, respectively. You might als
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Figure 12−6 Trimmed NURBS Surface
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Chapter 13 Selection and Feedback C
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As mentioned in the previous sectio
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void drawTriangle (GLfloat x1, GLfl
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} glPushMatrix (); glMatrixMode (GL
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different components of a primitive
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glMatrixMode (GL_PROJECTION); glPus
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} glPopMatrix(); /* draw last two w
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} if (mode == GL_SELECT) glLoadName
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} return 0; Try This Modify Example
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hand, selection in three dimensions
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A Feedback Example Example 13−7 d
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} glMatrixMode (GL_PROJECTION); glL
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Chapter 14 Now That You Know Chapte
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GL_STACK_OVERFLOW Command would cau
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extension that is available only on
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Each time through the loop, you cle
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} } set_color(i,j); glVertex2i(x(i,
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the bits of the appropriate color d
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C, ..., I, where region I is outsid
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Shadows Every possible projection o
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you’ll need to clear the stencil
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Figure 14−3 Dirichlet Domains If
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Video⎯Even if your machine doesn
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from specialized vertex arrays. Per
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applied to the top matrix on the st
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OpenGL State Variables The followin
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GL_FOG_START Linear fog start fog 0
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GL_TEXTURE_WRAP_x Texture wrap mode
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GL_DOMAIN 1D domain endpoints ⎯
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Appendix C OpenGL and Window System
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glFinish(), glXWaitGL() doesn’t r
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Use aglQueryVersion() to determine
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AGLDrawable aglGetCurrentDrawable (
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A shortcut for using OS/2 logical f
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directly. CreateDIBitmap() creates
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Appendix D Basics of GLUT: The Open
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depending upon whether the mouse ha
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Appendix E Calculating Normal Vecto
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evaluated at a particular point (x,
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Sometimes, you need to vary this me
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transformations.) After transformat
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As before, the inverses are obtaine
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Appendix G Programming Tips This ap
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computations. If your application r
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Appendix H OpenGL Invariance OpenGL
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Appendix I Color Plates This append
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Plate 4 The scene drawn with flat
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Plate 7 The scene drawn with one of
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. Plate 10 Teapots drawn with jitte
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Plate 14 Gray teapots drawn with di
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. Plate 18 Lighted, green teapots d
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Plate 21 An environment−mapped ob
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Plate 23 A magnification of the pre
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Plate 27 Sophisticated use of textu
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Plate 31 Another scene from a diffe
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itplane A rectangular array of bits
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decal A method of calculating color
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gamma correction A function applied
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A source of illumination which has
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A point, a line, a polygon, a bitma
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The 4×4 matrix that transforms tex
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Index
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