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College of Science and EngineeringDepartment of Computer Scienceand Information SystemsFinal Assessment PaperAcademic Year: 2011/2012 Semester: AutumnModule Title: Computer Graphics Module Code: CS4815Duration of Exam: 2 hours Percent of Semester Marks: 60Lecturer: P. Healy Paper marked out of: 100Instructions to Candidates:• Calculators are not permitted• Answer all questions• Please clearly number your answer to each question in the answer book provided to youSection 1.Fill in the blank (60 marks in total; 3 marks each)Please provide your answers to these questions in your answer book, clearly marked.answer, even if wrong, may gain you partial marks.A justified1. What is the 2-D matrix transformation to achieve a “mirror image” of a point about the y-axis?2. What is the 2-D matrix transformation to achieve point symmetry (through the origin)?3. What is the composition of matrices that achieves a 90 ◦ (anti-clockwise) rotation of an objectabout the point (a, b) in 2-D?4. In OpenGL the view direction is along the -axis; further away points aremore positive/negative (which?).5. Give an example of an impossible outcode for the Cohen-Sutherland algorithm. Assume youroutcode is lrbt.6. Using the Digital Differential Analyzer (DDA) Line Drawing Algorithm to draw a line from(x s , y s ) to (x e , y e ) the number of pixels “drawn” by the algorithm will be eitheror .7. Using the Bresenham Line Drawing Algorithm to draw a line from (x s , y s ) to (x e , y e ) the numberof pixels “drawn” by the algorithm will be either or .Page 1 of 3(please turn over)

p 1p 2(c) The Liang-Barsky clipping algorithm uses 4 parametric tests for the four borders of theclipping window, each of the formup k ≤ q kWrite down the conditions for when a point (x s + u∆x, y s + u∆y), 0 ≤ u ≤ 1 is in theclipping window defined by (x bl , y bl ) and (x ur , y ur ) and hence, derive the four inequalities.(6 marks.)2. Write a paragraph on each of the following topics in computer animation.(a) Morphing in Animation(b) Simulating Acceleration in Animation(6 marks.)(7 marks.)(c) Write a sentence explaining each of these concepts from a common approach to computeranimation(7 marks.)i. Storyboard Layoutii. Object Definitioniii. Key Frameiv. In-betweensPage 3 of 3