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This chapter defines system software and discusses two types of system software: operating systems and utility programs. You learn what an operating system is and explore user interfaces, operating systems features, and operating system functions.
Computer Graphics Lecture 32 Fasih ur Rehman 3D Transforms • The idea of 3D transforms is the same as that of 2D – A 3D point is represented by (x, y, z) – Homogeneous Coordinates are defined as • A 4th Coordinate is added to every 3D point • (x, y, z, t) represents (x/t, y/t, z/t) • (x, y, z, 0) represents infinity • (0, 0, 0, 0) is not allowed General 3D Homogeneous Transform x' y' z' w' a e i m b f j n c g k o d x h y l z p w Scaling • Scaling matrix x' y' z' w a 0 0 b 0 0 c 0 x y z w Translation • Translation matrix x' y' 0 a b x y z' w 0 c z 0 w Reflection • Reflection Matrix about yz – plane x' y' z' w • 0 0 0 0 0 x y z w What are other reflection matrices Rotation • Rotation about Z – axis x' y' z' w cos sin 0 sin cos 0 0 0 x y z w Rotation • Rotation about Y – axis x' y' z' w cos sin 0 sin 0 cos 0 x y z w Rotation • Rotation about X – axis x' y' z' w 0 cos sin 0 sin cos 0 x y z w Inverse Rotation Polygon Clipping • Difficult task • Polygon clipping may result in – Original Polygon – New polygon – Nothing • Trivial Accept • Trivial Reject Sutherland-Hodgman Clipping • • • Consider each edge of the view window individually Clip the polygon against the view window edge’s equation After doing all edges, the polygon is fully clipped Phong Reflection Model • • A simple model supports three models of light – matter interactions – Diffuse – Specular – Ambient and uses four vectors – normal – to source – to viewer Graphical User Interface (GUI) • Most of the system whether business or engineering are available with Graphical User Interfaces (GUI) thus enabling users to interact with there systems through graphical interfaces Attributes of GUI • Windows – • Icons – • may represent files or processes Menus – • Multiple windows enable variety of information to be prompted on the user’s screen at the same time Command selection possible from a menu instead of typing Pointing Device Design Process • • • Design requirements and view from the user (user centered design) Analyses and understanding of user activities Design prototype (paper based) – • Design prototype – • Evaluated by end user (modify if required) Evaluated by end user (modify if required) Produce dynamic design prototype Design Principles • • Experience and capabilities and needs of the system users must be taken into account during design process of UI Designers should be aware of people’s physical and mental limitations and should be convinced that people make mistakes Design Principles • User familiarity – The interface should use terms and concepts drawn from the experience of the users • Consistency • Minimal surprise • Recoverability – • e.g undo User guidance – help and prompts etc User System Interactions • • Two issues need to be addressed – How the information from user be provided to the system – How the processed information (from computer) be presented to the user? User System Interactions – Direct manipulation – Menu selection – Form fill-in – Command language Information Presentation • • • Information presentation means how to present processed information to the users It may be presented – Directly (e.g text) – Transformed like in graphical form Model-View-Controller approach supports multiple presentations of data Display Factors (Information) • • User requirement – Precise information – Data relationships Information values change frequency – • • Should user know immediately about the change? Response on change required or not from user Direct or transformed? Use of Colors • Extra dimension can be added • Can be used for warning • Guideline – Too many colors should not be used – Color code should also be provided and the user may be provided flexibility to change color code – Designing must be done for monochrome and colors should be added afterwards – Color codes should be consistent User Facilitation • The user guidance system (like on – line help, error messages and manuals) should be integrated with the user interface Animation • • Walt Disney created Animated objects – Mickey Mouse – Donald Duck Animate mean bring to life References • • Fundamentals of Computer Graphics Third Edition by Peter Shirley and Steve Marschner Interactive Computer Graphics, A Topdown Approach with OpenGL (Sixth Edition) by Edward Angel ... Line Clipping The view window is divided into regions as shown in the figure • Each region is assigned a 4-bit outcode Liang-Barsky Clipping • • • • • A line parallel to a clipping window edge has... assign shades or colors to the vertices of these objects Four Tasks – Projection – Primitive assembly – Clipping – Shading Hidden surface removal and visible Rasterization • • • Calculation of... three models of light – matter interactions – Diffuse – Specular – Ambient and uses four vectors – normal – to source – to viewer Graphical User Interface (GUI) • Most of the system whether business