Chapter 1

• you should read chapter 1.
• Components of a graphics system
  • CPU
  • GPU -
    • Specialized hardware optimized for rendering graphics.
    • Currently highly parallel (hundreds of processors)
    • We will discuss these in depth in the future.
  • Input Devices
    • Generally generate an "event" when an action takes place
    • We now care about more than just what key was pressed.
    • Traditionally there are two types of data
      • Button Presses
        • Keyboard is the big example here
        • But the buttons on a mouse
        • And most buttons on a wii mote
      • Positional data
        • The mouse will supply a change in x and a change in Y position.
        • It can not provide absolute coordinates.
        • An application (or underlying library) will keep track of the "logical" position based on these changes.
        • Mouse data is essentially 2d.
        • Spacemouse
          • A 3d mouse
          • Six different input values
          • Change in x,y and z location
          • Rotation in x, y and Z
        • Wiimote has
          • multiple buttons
          • Two 2d joysticks (with optional nunchuck)
          • Accelorometer, provides acceleration along all three axis.
          • An IR camera for spacial orientation.
          • A gyroscope (wiimote plus)
        • An iPhone 6, according to wikipeida has
          • Touch screen
          • microphone
          • 3 axis gyroscope
          • 3- axis accelerator
          • Compass
          • Proximity sensor
          • Ambient light sensor
          • Finger Print reader.
          • barometer
        • Look at this program
        • 
      • But a new something might be on the way...
        • Emotive Insight
          • 3-axis gyroscope (roll, pitch, yaw)
          • 3-axis accelerator (vertical, lateral, longitudinal acceleration),
          • 3-axis magnetometer (absolute change in position and orientation).
          • 5 EEG + 2 reference sensors
          • Watch the TED video starting around 4:30
    • Input devices will continue to change and grow.
  • Output Devices
    • 2d Display devices
      • CRT, LCD, ...
      • The screen is composed of a series of pixels (picture elements)
      • The number of pixels vertically and horizontally determine the resolution
      • Each pixel will have a way to produce between 1 (monochrome) and 3 colors
      • There will be a number of intensities for each color.
      • In computer graphics, there is an associated section of memory that holds the values which should be displayed
        • This is called a raster (on the monitor side)
    • Devices like the Oculus rift are just frequently just an extension of 2d devices
      • A different 2d image is somehow delivered to each eye
  • Software
    • Rendering Graphics is many layers deep.
      • Operating system
      • Some graphics support system
      • Some graphics library
      • Some application
    • Since I am most familiar with Linux/X/OpenGL we will discuss that
    • OS
      • Manages the hardware.
      • Drivers provide the low level software interface between the hardware and the kernel
    • The X11 window system is the graphics system for linux.
      • A client server based system.
      • The server
        • Is a program
        • Which interacts with the kernel.
          • Send requests for display (write bits to raster...)
          • Receive events from the input devices (via kernel)
        • Is network transparent, thus you can perform requests over the network.
      • The clients are applications
        • An xterminal, web browser ...
        • A strange client is the window manager
        • 
        • They communicate with the X server via the X protocol
        • Using calls from the X library

          •  
            Window XCreateWindow(Display *display, Window parent, int x, int y,
                                 unsigned int width, unsigned int height, 
            		     unsigned int border_width, int depth, 
            		     unsigned int class, Visual *visual,
            		     unsigned long valuemask, 
            		     XSetWindowAttributes *attributes);
            

      • The Xlib library is quite primitive
        • no support for buttons, menus, scroll-bars ...
        • So other libraries have been created.
        • FLTK, QT, GTK, ...
        • 
        • These are frequently constructed from component libraries as well.
        • Frequently designed to be cross platform!
    • The next layer up (for us) is a graphics system
      • This is a library which supports the creation of graphical objects
      • This will be the main study for the semester.
      • OpenGL, DirectX, ...
      • X supports drawing lines in 2D, and setting Pixels
      • OpenGL supports drawing triangles in 3D, creating lights, applying textures ....
      • OpenGL can be implemented
        • in software (Mesa)
        • Or Hardware (most modern graphics cards)
      • 
      • There are a number of utilities with OpenGL
        • GLU - OpenGL Utility Library:
          • Provided utility functions for early OpenGL
          • Is deprecated and will eventually go away.
          • But our author still uses it.
        • GLUT
          • A library which allows for simple windows, mouse/keyboard/...
          • Very simple, but we will use this as well.
        • GLX - OpenGL interface to the X window system
        • GLEW - OpenGL Extension Wrangler
          • A library that helps load the proper run-time mechanisms for openGL