Page 67 - DCAP313_LAB_ON_COMPUTER_GRAPHICS

Unit 4: Implementing Circle Algorithm

7. The “general” equation of a circle is: Notes
2
2
(a) x + y + Dx + Ey + F = 0 (b) x + y + Dx + Ey + F = 0
3
3
(c) x + y + Dx + Ey + F = 0 (d) x + y + Dx + F = 0
2
8. The “centre-radius” form of the equation is:
(a) x +y =r 2 (b) (x – h) + (y – k) = r 2
2
2
2
2
(c) Both (a) and (b) (d) None of these
9. The midpoint circle drawing algorithm works on the same midpoint concept as the ………..
line algorithm.
(a) DDA (b) Bresenham’s
(c) Both (a) and (b) (d) None of these
10. A line that intersects a circle at two points, is called:

(a) Circumference (b) Radius
(c) Secant (d) None of these
11. A line segment linking any two points on a circle is called:

(a) Circumference (b) Chord
(c) Secant (d) None of these
12. A line passing a circle and touching it at just one point is called:

(a) Tangent (b) Chord
(c) Secant (d) None of these
True of False

13. The positive orientation on the curve is then the orientation it inherits as the boundary of
its interior; the negative orientation is inherited from the exterior

(a) True (b) False
14. The circumference is the distance around the circle.
(a) True (b) False
15. The circumference is the distance around the circle.

(a) True (b) False

4.4 Summary

• All simple closed curves can be classified as negatively oriented (clockwise), positively
oriented (counterclockwise).
• The positive orientation on the curve is then the orientation it inherits as the boundary of
its interior; the negative orientation is inherited from the exterior.
• A line forming a closed loop, every point on which is a fixed distance from a center point.
• The circumference is the distance around the circle.

• The midpoint circle drawing algorithm works on the same midpoint concept as the
Bresenham’s line algorithm.

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