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CD2012 Principles of Interactive Graphics Lecture 04

CD2012 Principles of Interactive Graphics Lecture 04. Graphics Hardware Abir Hussain www.cms.livjm.ac.uk/cmsahus1. Previous Lecture. Transformation Translation: glTranslated ( x, y, z) Scaling: glScaled (x, y, z) Rotation: glRotated (angle, x, y ,z) Combining transformations

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CD2012 Principles of Interactive Graphics Lecture 04

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  1. CD2012Principles of Interactive GraphicsLecture 04 Graphics Hardware Abir Hussain www.cms.livjm.ac.uk/cmsahus1

  2. Previous Lecture • Transformation • Translation: glTranslated ( x, y, z) • Scaling: glScaled (x, y, z) • Rotation: glRotated (angle, x, y ,z) • Combining transformations • glLocaIdentity() • glMartrixMode() CD2012-02

  3. Today’s lecture and lab CD2012-02

  4. Display Devices Cathode Ray Tube (CRT) • A beam of electrons emitted by an electron gun, passes through the focusing system. • The light output of the phosphor decays rapidly • The display processor refreshes the phosphor around 60,70 times per second (60Hz, 70Hz) CD2012-02

  5. Other Display Technologies • Liquid crystal display (LCD) • The picture is displayed through light emitted from crystal • Flat screen for desktop computer and screen for laptop • Light emitting diodes (LED) • The picture is displayed through light emitted from diodes • Large screen for sporting events, concerts or commercial advertising • Plasma Panel display • Constructed from filling the areas between two glasses with neon gas • For Home TV, very thin, light, expensive CD2012-02

  6. Other Display Technologies LCD touch screen LED large screen CRT screen Plasma panel display CD2012-02

  7. Other display technologies • Head-Mounted displays • Use prisms and/or lens to project an image from small LCD or CRT screen • Provide an immerse experience by blocking out the real world • Fairly easy to set up • Can achieve good stereo quality • Heavy and do not fit well CD2012-02

  8. Graphics output frame butter • For CRT display, a scan controller converts information from the frame buffer and controls the scanning of electrons across the screen to draw the image • The scan controller draws pixels from left-to-right and top-to-bottom across the display • The complete screen is re-drawn at a given refresh rate e.g. 60Hz, 70Hz • For LCD display, data can be taken directly from the frame buffer so scan controller is not needed. CD2012-02

  9. Modern PC graphics cards • Current PC graphics cards may have 16, 32 or 64Mbytes of video memory. • This memory can hold one or more screen images plus textures. • Some graphics cards (e.g. GeForce2) may have hardware for • Transform calculations • Lighting calculations • Moving areas of memory in the frame buffer • Applying textures • These reduce load on the main system CPU CD2012-02

  10. Hard Copy Devices • Printers Originally the printers were used to produce text pages, however they are now widely accepted as graphical devices. • Plotters They are devices, which produce hard-copy line drawings. The most common type of plotters use ink pens for the generation of the drawing. In now days, many plotters use ink-jet sprays, laser beams and electrostatic methods. CD2012-02

  11. 2D Input Technologies • Keyboard - All computers are equipped with keyboards.They send strings of characters to the applications up on request • Mouse The mouse has been around since 1968 and has evolved into - One (Apple), Two (PC) and Three (UNIX) buttons - Ball or optical movement sensors - wired and wireless operation • The basic drawbacks of the mouse are as follows - Controlled by the arm and wrist muscles - not fine control - Needs space to operate - Is a relative positioning device - which is useful in some applications but not others CD2012-02

  12. 2D input technologies • Pen and graphics tablet-based devices - Allow fine detail control using finger muscles - Can (with tablet) allow absolute positioning - Useful in design and engineering applications • Tracker balls and tracker pads - Take up less space and useful for mobile applications - Can be difficult to control for small movements CD2012-02

  13. 3D Input Technologies • 3D input devices are less common as they are - more expensive - can be hard to learn to use - can be error prone and difficult to set up • Position trackers - e.g. Polhemus fastrak - Usually operate by creating a magnetic field - Sensors mounted on head, hand or elsewhere record movement in field - Can be distorted by metallic objects - Normally used for two purposes. CD2012-02

  14. Cybergloves and cybersuits Contain sensors which measure the bend of body joints Used with position trackers to record the full range of movement Very expensive May need to be calibrated for each user Can become less accurate with use 3D input technologies CD2012-02

  15. 3D input technologies • Space ball - allows movement in 3 dimensions The 3D Controller enable a whole new level of 3D interactive motion control. Can easily move or rotate 3D object by gently pushing, pulling or twisting the Power Sensor ball. CD2012-02

  16. Coursework 1 • Write a C++ program using OpenGL that presents a scene described in the coursework spec • The scene will include a basic set of graphical components as specified below • Plagiarised work will receive no marks. Plagiarism includes copying material from the Internet CD2012-02

  17. Coursework 1 guidelines Cars park • Car park spaces for parking cars • A number of parked cars • A barrier on the entrance and the exit of the car park • A charging machine CD2012-02

  18. Coursework 1 guidelines • Marks 1. Design document 30% 2. C++ Code accuracy, layout and readability 20% 3. C++ Code good use of OpenGL 20% 4. Extra features 10% interaction, animation, 3d effects 5. Demonstration 20% How well the program meets the coursework spec Are the objects recognisable ? Are colours and shapes used appropriately? CD2012-02

  19. Coursework 1 guidelines • Use the code in L:\CD2012 as a starting point (circles, transforms etc.) • The design report should properly explain how you went about constructing the scene • The display function should not be a long list of glVertex() calls • Split the drawing of the scene into different functions • Any questions - ask the module leader. CD2012-02

  20. Summary • Display devices - CRT, LED, LCD, plasma panel display - Frame buffer/ Graphics cards • Hard copy devices - printers , plotters • Interactive input devices - 2D input Keyboard, mouse, tracker ball/pads, - 3D input Position trackers, cybergloves, cybersuits, space ball • Coursework1 CD2012-02

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