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Com 417E: Computer Graphics Question Paper
Com 417E: Computer Graphics
Course:Computer Graphics
Institution: University Of Eldoret question papers
Exam Year:2015
Section A: Attempt ALL the questions from this section
Question One (12 Marks)
a). Explain the meaning of the following computer graphics terms. (3 mks)
i) Pixmap
ii) Frame
iii) GL
b). i) Give FOUR advantages of the flat panel displays over the traditional CRT technology (2 Mks)
ii) The beam penetration and the shadow mask ate two CRT methods for outputting color. State an advantage of each over the other. (1 Mk)
c). i) List the parameters of the flood fill region filling algorithm. (2 Mks)
ii) List two bad effects caused by the ‘aliasing’ feature in graphics (1 mk)
d). i) Explain the effect that the ray y-direction shear has on an image. Illustrate. (2 mks)
ii) explain the meaning of the graphics term ‘composite transformations’ (1 mk)
Question Two (12 marks)
a). Give the equation of each of the following 2D objects. (3 mks)
i) Circle
ii) Conic
iii) Polynomial
b). Give the matrix representation for the following transformations. (3 mks)
i) 3D rotation about z axis
ii) 2D Reflection about x axis
iii) 2D shear in y direction
c). Assume we rotate the point (4,1) about the origin and through the angle 90 degrees anticlockwise. Derive the new point using homogenous matrices. (3 mks)
d). i) List the names of any TWO GLUT inbuilt functions (1 mks)
ii) List the names of any FOUR GLUT constants. (2 mks)
Section B: Attempt any three Questions from this section
Question Three (12 Marks)
a).i) State the functions of the following CRT components. (2 mks)
i) Control grid
ii) Focusing anode
ii) Raster scan and random scan are two CRT methods for outputting graphics. State an advantage of each over the other. (1 mk)
b). Describe the plasma panels output devices. (3 mks)
c). Describe joysticks as graphics input devices (3 mks)
d). The dot matrix printer is a graphics output device. Describe how it outputs characters. (3 mks)
Question Four (12 Marks)
a). The DDA line generation algorithm uses symmetry to generate a line. Explain two main problems that this symmetry solves. Illustrate. (3 mks)
b). The mid-point circle generation algorithm is an improvement over the simple circle generation method.
i) explain two limitation with the simple method that the mid-point method solves. Give simple illustration. (3 mks)
ii) Write the mid-point circle generation algorithm. (3 mks)
c) Describe the super-sampling method of anti-aliasing. (3 mks)
Question Five (12 Marks)
a). Assume we want to rotate the 2D triangle (1.4), (3,0), (0,2) about the vertex (1,4) and through 90 degrees anticlockwise.
i) Give the steps of doing so (1.5 mks)
ii) Derive the effective transformation matrix for the transformation using homogenized co-ordinates. ( 3.5 mks)
iii). Hence derive the new line’s vertices (2 mks)
b). Assume a 3D line (4,1,0), (2,0,3) is transformation using the following Open GL statement. Derive the resulting line. (3 mks)
glRotatef (90,1,0,0)
c). Explain the meanings of the following graphics terms concerning viewing (2 mks)
i). World co-ordinates
ii) Clipping
Question Six (12 Marks)
a). i) State the difference between the viewing terms ‘window’ and ‘viewport’ (1 mk)
ii) Explain the following two transformations types (2 marks)
-Projection transformation
-Viewport transformation
iii) List the parameters of the glFrustum() function (1 mk)
b). State the work of the following Open GL transformation functions. Also list the parameters. (4 mks)
i) gluPerspective()
ii) glOrtho()
c). Write a function named display that should be called by glutDisplayFunc() in the main() function of an OPENGL graphics program that draws a white line from the coordinates (-10,10) to the coordinates (10,-10). (4 mks)
Question Seven (12 Marks)
Write a complete Open GL program to output a yellow triangle with coordinates (4,2), (1,5), (3,4) on a black background. Also, the user should be able to:
- Rotate the triangle left through an angle of 20 degrees (by pressing key ‘1’) or
- Rotate the triangle right through an angle of 20 degrees (by pressing key ‘2’) or
- Rotate the triangle up through an angle of 20 degrees (by pressing key ‘3’) or
- Rotate the triangle down through an angle of 20 degrees (by pressing key ‘4’)
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