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Welcome! Today: Administrative stuff. Introductory remarks. Voting on course arrangements.

Welcome! Today: Administrative stuff. Introductory remarks. Voting on course arrangements. Basic graphics + OpenGL revision or curves & surfaces. Administrivia. Web page: http://www.cse.unsw.edu.au/~cs9018 Includes a notice board + message board.

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Welcome! Today: Administrative stuff. Introductory remarks. Voting on course arrangements.

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  1. Welcome! • Today: • Administrative stuff. • Introductory remarks. • Voting on course arrangements. • Basic graphics + OpenGL revision or curves & surfaces. COMP9018 - Advanced Graphics

  2. Administrivia • Web page: • http://www.cse.unsw.edu.au/~cs9018 • Includes a notice board + message board. • Tim & I will read/contribute regularly. • Also lots of links and stuff. COMP9018 - Advanced Graphics

  3. Administrivia • People • Waleed (that's me) (waleed@cse.unsw.edu.au) • Tim (the smart guy) (lambert@cse.unsw.edu.au) • Who to e-mail: • Enrolments: waleed • Software problems: waleed • Web issues: waleed • Lecture material: whoever presented it • Tricky questions: lambert • Lecturer-in-charge/complex admin: lambert COMP9018 - Advanced Graphics

  4. Attitude to the course • Graphics is HUGE! • No one person can grasp all of it • Tim & I know stuff but we don't know it all: guides rather than experts COMP9018 - Advanced Graphics

  5. Fourth year • This is a fourth year subject/graduate subject • So rules are a little different. • Smaller numbers = • more flexibility • higher standard (we hope) • more interactivity COMP9018 - Advanced Graphics

  6. Things we’d like you to do • Common sense: • Doing the best you can in the subject • Respecting fellow students • Shutting up when you're not supposed to talk • Participating • Doing the preparation/homework we ask you to • Not cheating (we'll come down HARD on cheats) • Actually showing up to appointments/not expecting us to be available all the time COMP9018 - Advanced Graphics

  7. Some basic rules • Questions allowed at any time ... but raise your hands and wait for us to ask • Open to suggestions • Academic etiquette: You’re allowed to borrow or copy, but when you do, ACKNOWLEDGE it. COMP9018 - Advanced Graphics

  8. Anybody scared? • Can discontinue without failure until end of week 4 (I think) COMP9018 - Advanced Graphics

  9. Run through handout • See handouts COMP9018 - Advanced Graphics

  10. Voting issues • Vote on lots of critical things • ... but you can't vote people out of the course • Course isn't going to get smaller and smaller as time goes on, 'til last person gets an HD COMP9018 - Advanced Graphics

  11. Issue 1 • Language preference • C/C++ vs Java • Any other bizarre languages? Fortran, Perl, Python, Haskell? • Examples in both? • Assignments: both allowed COMP9018 - Advanced Graphics

  12. Issue 2 • Last time had a local games company give a seminar/demo • Couldn’t organise film person; but will try again this year … if you are interested • Vote? COMP9018 - Advanced Graphics

  13. Issue 3 • Syllabus material • Rough outline of what was covered last time • Any topics from the list people feel strongly about? • What to drop to include? COMP9018 - Advanced Graphics

  14. Week 13 demo night • Put it in your calendars • No lectures week 13 • From 5pm to 10pm • Can bring in own equipment if you like • Do you guys want me to ask outsiders (e.g. industry people) to attend? COMP9018 - Advanced Graphics

  15. Text • Graphics has 2 properties: • Diverse • Fast-moving • Generally means textbooks get out of date quickly • The Net is a very good resource. • See links on Web page for online info. COMP9018 - Advanced Graphics

  16. … but if you really want … • Textbooks • Computer Graphics: Principles & Practice Brown et al. Known as “Old Testament” • Advanced Animation & Rendering Techniques by Watt & Watt. Known as “New Testament” • OpenGL Programming Guide by OpenGL ARB. Known as the “Red Book” or “Lego book”. Available online. COMP9018 - Advanced Graphics

  17. Labs • Have hardware acceleration (TNT2 cards -- not great, but better than nothing) • Linux is official platform (not by choice, really) • For compatibility: Only use standard Java libraries + gl4java; for C/C++: standard libraries + OpenGL + GLU + GLUT + MUI ... must compile with gcc • If you want something else, let us know. COMP9018 - Advanced Graphics

  18. Project possibilities • Write your own game • Write your own modeller • Extend an open source program with some feature • Make a short CG movie • But be careful with your time budget! Don’t want you to fail other subjects (almost happened last time) COMP9018 - Advanced Graphics

  19. Examples from last time • Some examples • Movie scenes: • Lord of the Rings + modelling tools (4 ppl). • Story of a fly. • Games: • 3D pool (2 ppl). • 3D tetris • 3D multiplayer networked robot/shooter/transfomer game (2ppl). • Halflife level modelled on Ground & Basement of CSE. • Global thermonuclear war with Ronald Raygun, COMP9018 - Advanced Graphics

  20. More examples • Interactive applications • Origami tutor • CT-Scan lung visualiser • Photo-etching animation. • Artificial creatures lab • Lego modeller • Screen savers: • Rollercoaster generator. • Rubik’s snake. COMP9018 - Advanced Graphics

  21. Special resources • Generally • Increased disk quota (+ 20Mb) • Increased IP quota (+ 200Mb) • Trying to arrange special access to bongo lab. COMP9018 - Advanced Graphics

  22. Project-specific • With access to bongo: • 6 Maya floating licenses. • VirTools. • May be able to arrange other tools, but may be difficult. COMP9018 - Advanced Graphics

  23. Special resources • Available on request • Good for the project • Two clusters: • vina: 18 machines, 1x866MHz, 256MB RAM, Linux • tines: 17 machines, 2x450MHz, 512MB RAM, Linux COMP9018 - Advanced Graphics

  24. Software available • GLUT 3.7 • OpenInventor • POVRay • Blue Moon Rendering Tools (RenderMan compatible, radiosity support) • Java3D • Blender COMP9018 - Advanced Graphics

  25. Break time • After break, revision of basic graphics + OpenGL or • Get straight into curves and surfaces. • Vote!! COMP9018 - Advanced Graphics

  26. Graphics Revision • What is graphics? • About anything computer generated that you see: • In print • On a monitor • On television • At the movies • At art exhibitions COMP9018 - Advanced Graphics

  27. Usual representation • Most common representation of an image is a bitmap: A 2D array of pixels • Each pixel holds a description of the colour of that point • The bitmap that holds the current image on display is called the frame buffer COMP9018 - Advanced Graphics

  28. Representing colour • Usual way is as a combination of red green and blue; but monochrome is also possible • Different approaches: • Fixed set of colours (e.g. CGA, EGA). Colour represented by a bit value • Each pixel stores an index into an array of customisable colours (e.g. VGA) aka colour index mode • Each pixel directly represents its colour directly (e.g. HighColor, TrueColor) aka RGB mode. COMP9018 - Advanced Graphics

  29. Objects • Primitive objects in graphics: • Points: A single coordinate. • Lines: usually a parametric representation (a + tb; 0 < t < 1) or a pair of coordinates. • Polygons: A sequence of points. Usually talk of closed polygons (end is same as beginning) COMP9018 - Advanced Graphics

  30. But first ... what is a polygon? • Sequence of points enclosing a plane. • In 3D, we use polygons that only have one face ... there is no "back" of a polygon. • How do you decide which way a polygon is facing? Convex polygon Concave polygon COMP9018 - Advanced Graphics

  31. Using the normal • If not specified, use the right hand rule. D B C C A A B D Out of the page Into the page COMP9018 - Advanced Graphics

  32. Types of polygon • Nasty polygons: • Non-planar: Not all vertices are in the same plane. • Self-intersecting: Polygons that intersect themselves are problematic. • Concave: Have internal angles greater than 180 degrees. Complicate lots of things. • We'll assume we don't have any of these. COMP9018 - Advanced Graphics

  33. Transformations • Frequently want to represent "doing" things to objects. Doing things = "transformations". • Many useful transformations can be represented as matrices applied to vectors • Homogeneous matrices are used so that translations can be represented as matrices. • Homogenous means 1 more dimension than underlying space: 3x3 for 2D, 4x4 for 3D COMP9018 - Advanced Graphics

  34. Why homogenous? • Allows us to represent translations as a matrix multiply -- making almost all interesting modelling transforms COMP9018 - Advanced Graphics

  35. Example transforms • Rotate about origin in 2D • Scale • Translate • Rotation about y axis in 3D? • Perspective • etc etc etc COMP9018 - Advanced Graphics

  36. Window to Viewport mapping • Maps part of the 2D plane of interest onto the monitor • Usually includes an inversion because monitors are upside down • Except with OpenGL, which maintains a Cartesian representation COMP9018 - Advanced Graphics

  37. Clipping • Finding bits outside the screen • Why? • Speed ... don't render what we don't need to render • Avoid overwriting random bits of memory COMP9018 - Advanced Graphics

  38. Graphics pipelines - 2D • Start with description of 2D objects (lines, points, polygon) • Apply transformations to position them • Apply window-to-viewport mapping • Clip • Rasterise COMP9018 - Advanced Graphics

  39. OpenGL • Provides a general platform independent graphics API that's a rich but thin and efficient layer over the hardware. • About 150 commands • For real-time 2D and 3D point, line and polygon based rendering • Also does 3D lighting and texturing COMP9018 - Advanced Graphics

  40. What OpenGL doesn't do • Doesn't deal with windows or I/O • Doesn't handle curves or curved surfaces • Doesn't have a file format or handle complicated objects - only points lines and polygons • Doesn't create image files COMP9018 - Advanced Graphics

  41. Companion libraries to OpenGL • GLU (GL utility): Does tesselation of curved surfaces, some more flexible projections, etc • GLUT (GL utility toolkit): A platform-independent window and I/O system (also now includes MUI - micro user interface for menus, dials etc) • WGL, GLX: Platform-specific window and I/O systems • OpenInventor: Provides high-level scene graph libraries COMP9018 - Advanced Graphics

  42. OpenGL and Java • Too slow to have an OpenGL implementation in Java. • So usual technique: use a Java native interface to OpenGL and provide a Java interface to it. • We’ll be using GL4Java COMP9018 - Advanced Graphics

  43. Why not use Java3D? • Java3D is a high-level scene graph library • More like OpenInventor than OpenGL • Java3D is implemented on top of OpenGL! • Have a look at Java3D later • Grrr ... COMP9018 - Advanced Graphics

  44. More about OpenGL • Funky thing about it: It's basically a state machine - i.e. another computer • Most commands don't produce visible output - they set up the state for what happens between glBegin and glEnd commands • Interesting stuff happens between the glBegin and the glEnd COMP9018 - Advanced Graphics

  45. Open GL + C/Java • Anatomy of a simple OpenGL program in C/GLUT - hello.c • ... from the OpenGL Programmer's Guide • Java’s pretty much the same. COMP9018 - Advanced Graphics

  46. The matrix stack • How OpenGL does transformations • A perfect fit for scene graph traversal • How matrix stacks work COMP9018 - Advanced Graphics

  47. Basic operations • glMatrixMode(Mode)sets the matrix stack we want to use. For now, only concerned with GL_MODELVIEW. • glPushMatrix()copies current top of matrix stack and pushes on top of stack. • glPopMatrix()pops off the top of the stack • glLoadIdentity()loads identity matrix onto top of stack COMP9018 - Advanced Graphics

  48. How matrix stack is used. • When you do glTranslatef(...)it actually postmultiplies by the matrix on top of stack and puts it back on top of the stack. • Means that last matrix op is done first. COMP9018 - Advanced Graphics

  49. Example - On blackboard • Initialise stack with glMatrixMode(GL_MODELVIEW);glLoadIdentity(); • Scale by 2glScaled(1.0, 2.0, 1.0); • Rotate around x by 90glRotated(90, 1, 0, 0); • Push on stackglPushMatrix(); I S(2) S(2).R(90) S(2).R(90) copy S(2).R(90) COMP9018 - Advanced Graphics

  50. Example - cont'd • Translate by a glTranslatef(a.x, a.y, a.z); • Draw a point on screen.glBegin(GL_POINTS);glVertex3f(1,1,1);glEnd();would actually draw at S(2).R(90).Tr(a).(1,1,1) • Pop off stackglPopMatrix(); S(2).R(90).Tr(a) S(2).R(90) S(2).R(90)Tr(a) S(2).R(90) S(2).R(90) COMP9018 - Advanced Graphics

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