Chapter 1: Introduction

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Chapter 1 Introduction

• Admin
• Lecture slots Monday 8-945, Tuesday 915-1100.
• Book F. Hill, Computer Graphics Using OpenGL
  (Little Big Bookstore)
• Evaluation 3hr closed book, 8th week (50)
  weekly pracs (50)
• Pracs Windows or Linux, OpenGL. CAREFUL when
  using 3D Studio Max.
• This is a fun course, but also a LOT of hard
  work.

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Chapter 1 Introduction

• Week 1 Introduction and OpenGL (Hill, Ch. 1,2).
• Week 2 Windows and viewports vector tools
  (Hill, Ch. 3,4).
• Week 3 Vector tools (continued) (Hill, Ch. 4).
• Week 4 Transformations on objects (Hill, Ch. 5).
  
• Week 5 Polygonal meshes (Hill, Ch. 6).
• Week 6 3D viewing (Hill, Ch. 7).
• Week 7 Lighting and face realism (Hill, Ch. 8).
• Week 8 Exam Wednesday 0900

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Chapter 1 Introduction

• 1.1 What is computer graphics (CG)?
• Simply pictures
• Tools
• Field of study
• 1.2 Where is CG used?
• Art, entertainment, publishing
• Image processing
• Process monitoring, simulations, CAD
• Scientific visualization

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Chapter 1 Introduction

• 1.3 Elements of pictures created in CG
• Output primitives and attributes
• Polylines
• Text
• Filled regions
• Raster images
• 1.3.1 Polylines
• Connected sequence of straight lines

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Chapter 1 Introduction

• Edge, vertex, polygon, simple polygon
• Attributes color, thickness, dashing, endpoint
  blending

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Chapter 1 Introduction

• 1.3.2 Text
• Font, color, size, spacing, orientation
• Tilting (graphs)
• 1.3.3 Filled regions
• Filled shape boundary (polygon)
• Filling used for shadow effects

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Chapter 1 Introduction

• 1.3.4 Raster image
• Consists of cells (called pixels) with color
  value
• Stored as array of numerical values
• Bitmap 0-1
• Created as hand-designed, or computed, or
  scanned.
• Computed straight lines jaggies
• Easy manipulation (filters, cleanup)

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Chapter 1 Introduction

• 1.3.5 Shades of gray and color in raster images
• Pixel depth n bits gt 2n values (at least 256)
• Smaller pixel depth gt loss in quality. Banding.
• Color RGB
• Color depth gt sum of bits for each color
• High quality (true color) 24 bits (eye
  perception)
• 1.4 Graphics Display Devices
• 1.4.1 Line drawing (plotters) cross-hatching

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Chapter 1 Introduction

• 1.4.2 Raster displays (video monitor, flat-panel
  displays, printers)
• Display surface (X,Y)
• Frame buffer memory to hold display pixels,
  with scan controller.

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Chapter 1 Introduction

• Some hardware (video monitor) requires refresh
  entire frame buffer scanned out to display many
  times per second.

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Chapter 1 Introduction

• Video monitors
• CRT
• Digital-to-analog converters (DACs)
• Refresh 60x per second to prevent flicker.
• Scanning per line

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Chapter 1 Introduction

• 1.4.3 Indexed Color and the LUT
• Programmable association between pixel value and
  color
• Bits in frame buffer acts as index into LUT.
• Palette set of possible colors AT ONE TIME.
• 1.4.4 Other raster display devices flat-panel,
  LCD, active matrix panels, plasma panel
• 1.4.5 Hard-copy raster devices film recorder,
  laser printer, inkjet plotter. PostScript.
• 1.5 Graphics input primitives and devices
• Selfstudy.

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Chapter 2 Drawing in OpenGL

• 2.1 Getting started
• Environment window, coordinate system,
  elementary drawing routines
• 2.1.1 Device-independence and OpenGL
• Libraries
• 2.1.2 Windows-based Programming
• Event-driven, event queue and callbacks
• System-dependent (glut)
• Example Fig. 2.2

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Chapter 2 Drawing in OpenGL

• include ltgl/Gl.hgt
• include ltgl/glut.hgt
• //ltltltltltltltltltltltltltltltltltltltltltltltlt main
  gtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgt
• void main(int argc, char argv)
• // initialize
• // create screen window
• glutDisplayFunc (myDisplay)
• glutMouseFunc (myMouse)
• glutKeyboardFunc (myKeyboard)
• glutMainLoop() // go into a perpetual
  loop

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Chapter 2 Drawing in OpenGL

• 2.1.3 Opening a window for drawing (framework)
• include ltgl/Gl.hgt
• include ltgl/glut.hgt
• //ltltltltltltltltltltltltltltltltltltltltltltltlt main
  gtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgt
• void main(int argc, char argv)
• glutInit(argc, argv) // initialize
  the toolkit
• glutInitDisplayMode(GLUT_SINGLE GLUT_RGB) //
  set display mode
• glutInitWindowSize(640,480) // set window
  size
• glutInitWindowPosition(100, 150) // set window
  position on screen
• glutCreateWindow("my first attempt") // open
  the screen window
• glutDisplayFunc(myDisplay) // register
  redraw function
• myInit()
• glutMainLoop() // go into a perpetual
  loop

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Chapter 2 Drawing in OpenGL

• 2.2 Drawing basic graphics primitives
• Establish coordinate system
• Line drawing primitives glBegin, glEnd,
  vertices
• Example
• glBegin (GL_POINTS)
• glVertex2i(100,50)
• glVertex2i(100,130)
• glVertex2i(150,130)
• glEnd()
• OpenGL commands glVertex2i ()

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Chapter 2 Drawing in OpenGL

• OpenGL data types GLint, GLfloat
• OpenGL state current state variables.
• glColor3f (red, green, blue)
• glClear (GL_COLOR_BUFFER_BIT)
• Establish coordinate system
• Matrices and transformations (ch. 3)
• Fig. 2.10 A complete OpenGL program
• Note glFlush()

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Chapter 2 Drawing in OpenGL

• 2.2.1 Drawing dot constellations
• The Big Dipper
• The Sierpinski Gasket
• Simple dot plots (note scaling and shifting,
  which are affine transformations)
• 2.3 Line Drawings
• glBegin (GL_LINES)
• glVertex2i(40, 100)
• glVertex2i(202, 96)
• glEnd()

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Chapter 2 Drawing in OpenGL

• More than 2 vertices paired
• 2.3.1 Drawing polylines and polygons
• Polyline collection of joined line segments,
  specified by ordered list of points.
• OpenGL GL_LINE_STRIP (open line segment)
• GL_LINE_LOOP (closed line segment not fillable
  area GL_POLYGON)
• Examples line graphs, polylines from file,
  parameterizing figures, polyline drawer

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Chapter 2 Drawing in OpenGL

• 2.3.2 Line drawing with moveto() and lineto()
• Current position
• 2.3.3 Drawing aligned rectangles
• glRecti(x1,y1,x2,y2)
• 2.3.4 Aspect ratio of aligned rectangle
• width/height
• NB! Work through all practice exercises on pp.
  6061.

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Chapter 2 Drawing in OpenGL

• 2.3.5 Filling polygons
• Must be convex!
• 2.3.6 Other graphics primitives
• GL_TRIANGLES,GL_QUADS,GL_TRIANGLE_STRIP
• GL_TRIANGLE_FAN,GL_QUAD_STRIP

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Chapter 2 Drawing in OpenGL

• 2.4 Simple mouse and keyboard interaction
• glut callbacks on events
• glutMouseFunc, glutMotionFunc, glutKeyboardFunc
• 2.4.1 Mouse interaction selfstudy
• 2.4.2 Keyboard interaction selfstudy
• 2.6 Case studies SELFSTUDY

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Chapter 2 Drawing in OpenGL

• Programming Task 1 Implement Case Study 2.5
  (Polyline Stippling), p. 75, in Hill.
• Familiarize yourself with OpenGL, Linux (or
  Windows) and C/C.
• The usual rules for programming projects hold
• No extensions (demo Monday 0800)
• No copying/cheating
• Accompanying report to be handed in at demo