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Introduction to Computer Graphics

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  1. Introduction to Computer Graphics Mohan Sridharan Based on Slides by Edward Angel and Dave Shreiner CS4395: Computer Graphics

  2. Overview • Slides based on book by Edward Angel and Dave Shreiner: Interactive Computer Graphics, A Top-down Approach with Shader-Based OpenGL (Sixth Edition), Addison-Wesley, 2011. • Lots of resources on companion website: http://www.cs.unm.edu/~angel/BOOK/INTERACTIVE_COMPUTER_GRAPHICS/SIXTH_EDITION/ • Some useful resources listed on course website: http://www.cs.ttu.edu/~smohan/Teaching/Spring12_CS4395/index.html CS4395: Computer Graphics

  3. Objectives • Broad introduction to Computer Graphics: • Software. • Hardware. • Applications. • Top-down approach: • Shader-Based OpenGL compatible with: • OpenGL 3.1 (and later). • Open GL ES 2.0 • webGL CS4395: Computer Graphics

  4. Prerequisites • Good programming skills in C (or C++). • Basic Data Structures: • Linked lists. • Arrays. • Geometry. • Simple Linear Algebra. CS4395: Computer Graphics

  5. Requirements • 4-5 programming projects: • Increasing levels of difficulty: totally 65% of grade. • Will move from 2D to 3D with lighting and texture. • Term Project: • You pick!  • Substantial challenge since it constitutes 25% of grade. • Responses + classroom participation: 10% CS4395: Computer Graphics

  6. Resources • Can run OpenGL on any system: • Windows: check graphics card properties for level of OpenGL supported. • Linux. • Mac: may need extensions for 3.1 equivalence. • Get GLUT from web if needed: • Provided on Macs. • freeglut available on web. • Get GLEW from web. • WebGL: most newer browsers. CS4395: Computer Graphics

  7. References • www.opengl.org • Standards documents, sample code. • The OpenGL Programmer’s Guide (the Redbook) 7th Edition: • The definitive reference. • Mixes 3.0 and 3.1 • OpenGL Shading Language, 3rd Edition. • OpenGL ES 2.0 Programming Guide. CS4395: Computer Graphics

  8. Outline: Part 1 • Part 1: Introduction. • Text: Chapter 1. • Chapter topics: • What is Computer Graphics? • Applications Areas. • History. • Image formation. • Basic Architecture. CS4395: Computer Graphics

  9. Outline: Part 2 • Part 2: Basic OpenGL. • Text: Chapter 2. • Chapter topics: • Architecture. • GLUT. • Simple programs in two and three dimensions. • Basic shaders and GLSL. • Interaction. CS4395: Computer Graphics

  10. Outline: Part 3 • Part 3: Three-Dimensional Graphics. • Text: Chapters 3-5. • Chapter Topics: • Geometry. • Transformations. • Homogeneous Coordinates. • Viewing. • Lighting and Shading. CS4395: Computer Graphics

  11. Outline: Part 4 • Part 4: Implementation. • Text: Chapter 6. • Chapter topics: • Approaches (object vs. image space). • Implementing the pipeline. • Clipping. • Line drawing. • Polygon Fill. • Display issues (color). CS4395: Computer Graphics

  12. Outline: Part 5 • Part 5: Discrete Methods. • Text: Chapter 7. • Chapter topics: • Buffers. • Texture Mapping. • Shader Applications. • Compositing and Transparency. CS4395: Computer Graphics

  13. Outline: Part 6 • Part 6: Hierarchy and Procedural Methods. • Text: Chapters 8-9. • Chapter topics: • Tree Structured Models. • Traversal Methods. • Scene Graphs. • Particle Systems. CS4395: Computer Graphics

  14. Outline: Part 7 • Part 7: Curves and Surfaces. • Text: Chapter 10. CS4395: Computer Graphics

  15. Outline: Part 8 • Part 8: Advanced Rendering. • Text: Chapter 11. • We are finally done! CS4395: Computer Graphics

  16. Extra Lectures • Marching Squares. • Virtual Trackball. • Environment Mapping. • Shadows, fractals. • Display Issues. • Bump Mapping, sampling and aliasing. • Reflection and transmission. CS4395: Computer Graphics

  17. What is Computer Graphics? CS4395: Computer Graphics

  18. Computer Graphics • Computer graphics deals with all aspects of creating images with a computer: • Hardware. • Software. • Applications. CS4395: Computer Graphics

  19. Example • Where did this image come from? • What hardware/software did we need to produce it? CS4395: Computer Graphics

  20. Preliminary Answer • Application: object is an artist’s rendition of the sun for an animation to be shown in a domed environment (planetarium). • Software: Maya for modeling and rendering but Maya is built on top of OpenGL. • Hardware: PC with graphics card for modeling and rendering. CS4395: Computer Graphics

  21. Basic Graphics System Output device Input devices Image formed in frame buffer CS4395: Computer Graphics

  22. CRT Can be used either as a line-drawing device (calligraphic) or to display contents of frame buffer (raster mode) CS4395: Computer Graphics

  23. Computer Graphics: 1950-1960 • Computer graphics goes back to earliest days of computing: • Strip charts. • Pen plotters. • Simple displays using A/D converters to go from computer to calligraphic CRT. • Cost of refresh for CRT too high: • Computers slow, expensive, unreliable (not anymore!). CS4395: Computer Graphics

  24. Computer Graphics: 1960-1970 • Wireframe graphics: • Draw only lines! • Sketchpad. • Display Processors. • Storage tube. wireframe representation of sun object CS4395: Computer Graphics

  25. Sketchpad • Ivan Sutherland’s PhD thesis at MIT: • Recognized the potential of man-machine interaction. • Loop: • Display something. • User moves light pen. • Computer generates new display. • Sutherland also created many of the now common algorithms for computer graphics. CS4395: Computer Graphics

  26. Display Processor • Rather than have the host computer try to refresh display, use a special purpose computer called a display processor(DPU). • Graphics stored in display list/file on display processor. • Host compiles display list and sends to DPU. CS4395: Computer Graphics

  27. Direct View Storage Tube • Created by Tektronix: • Did not require constant refresh. • Standard interface to computers: • Allowed for standard software. • Plot3D in Fortran. • Relatively inexpensive: • Opened door to use of computer graphics for CAD community. CS4395: Computer Graphics

  28. Computer Graphics: 1970-1980 • Raster Graphics. • Beginning of graphics standards. • IFIPS: • GKS: European effort. • Becomes ISO 2D standard. • Core: North American effort. • 3D but fails to become ISO standard. • Workstations and PCs. CS4395: Computer Graphics

  29. Raster Graphics • Image produced as an array (the raster) of picture elements (pixels) in the frame buffer. CS4395: Computer Graphics

  30. Raster Graphics • Allows us to go from lines and wire frame images to filled polygons! CS4395: Computer Graphics

  31. PCs and Workstations • Although we no longer make the distinction between workstations and PCs, they evolved from different roots: • Early workstations characterized by: • Networked connection: client-server model. • High-level of interactivity. • Early PCs included frame buffer as part of user memory: • Easy to change contents and create images. CS4395: Computer Graphics

  32. Computer Graphics: 1980-1990 Realism comes to computer graphics  smooth shading environment mapping bump mapping CS4395: Computer Graphics

  33. Computer Graphics: 1980-1990 • Special purpose hardware: • Silicon Graphics geometry engine: VLSI implementation of graphics pipeline. • Industry-based standards: • PHIGS. • RenderMan. • Networked graphics: X Window System. • Human-Computer Interface (HCI). CS4395: Computer Graphics

  34. Computer Graphics: 1990-2000 • OpenGL API. • Completely computer-generated feature-length movies (Toy Story) are successful. • New hardware capabilities: • Texture mapping. • Blending. • Accumulation, stencil buffers. CS4395: Computer Graphics

  35. Computer Graphics: 2000- • Photorealism. • Graphics cards for PCs dominate market: Nvidia, ATI. • Game boxes and game players determine market direction. • Computer graphics routine in movie industry: Maya, Lightwave. • Programmable pipelines. CS4395: Computer Graphics

  36. What next? • Overview of image formation. • Overview of graphics architectures. CS4395: Computer Graphics