Page 149 - DCAP504_Computer Graphics

Computer Graphics

(b) The sign(x-xmax) indicates that the:
(i) Endpoint is above the window (ii) Endpoint is to the left of the window
(iii) Endpoint is to the right of the window (iv) Endpoint is below the window
(c) The endpoints of the line which lies within the window fall under …………….. category.

(i) Visible (ii) Invisible
(iii) Clipping candidate (iv) Parametric
(d) Clipping algorithm can be applied in world co-ordinates such that the picture of the object
inside the window is mapped to……………………...
(i) Clip window (ii) Transformation matrices

(iii) Viewport (iv) Device co-ordinates
9.7 Review Questions
1. What is clipping? Mention the types of clipping.
2. Explain how point clipping works.
3. "Line clipping depends on the position of the endpoints with reference to the window edges".
Explain with diagram.
4. What are the two steps followed in Cohen Sutherland algorithm to determine the category of a
line?
5. In Midpoint Subdivision algorithm, when do you start subdividing a line?
6. Explain with diagram the Midpoint Subdivision algorithm.
7. Explain Liang-Barsky Algorithm.
Answers: Self Assessment
1. (a) False (b) True (c) False (d) True (e) True (f) False

2. (a) Clipped part (b) Viewport clipping (c) Window edges
(d) Region code (e) Parametric line equations
3. (a) Clip window (b) Endpoint is to the right of the window
(c) Visible (d) Device co-ordinates
9.8 Further Readings

Godse A.P, Godse D.A. Computer Graphics And Multimedia, Technical Publications, Pune
Sinha and Udai, Computer Graphics, Tata McGraw-Hill, New Delhi
Zhigang Xiang, Computer Graphics, Tata McGraw-Hill Education

http://i.thiyagaraaj.com/tutorials/computer-graphics/clipping-techniques/1-point-
clipping

www.skytopia.com/project/articles/compsci/clipping.html

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