CD2012 Principles of Interactive Graphics Lecture 04 Graphics Hardware Abir Hussain

© JMU, 2003CD Previous Lecture Transformation –Translation: glTranslated ( x, y, z) –Scaling: glScaled (x, y, z) –Rotation: glRotated (angle, x, y,z) Combining transformations –glLocaIdentity() –glMartrixMode()

© JMU, 2003CD Today’s lecture and lab

© JMU, 2003CD 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)

© JMU, 2003CD 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 –C onstructed from filling the areas between two glasses with neon gas –For Home TV, very thin, light, expensive

© JMU, 2003CD Other Display Technologies Plasma panel display CRT screen LCD touch screen LED large screen

© JMU, 2003CD 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

© JMU, 2003CD 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.

© JMU, 2003CD 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

© JMU, 2003CD 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.

© JMU, 2003CD D 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

© JMU, 2003CD D 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

© JMU, 2003CD D 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.

© JMU, 2003CD D input technologies 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

© JMU, 2003CD D 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.

© JMU, 2003CD 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

© JMU, 2003CD 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

© JMU, 2003CD Coursework 1 guidelines Marks 1. Design document 30% 2. C++ Code accuracy, layout and readability20% 3. C++ Code good use of OpenGL20% 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?

© JMU, 2003CD 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.

© JMU, 2003CD 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 P osition trackers, cybergloves, cybersuits, space ball Coursework1