Explore topic-wise InterviewSolutions in .

Correct option is (a) connected

The EXPLANATION is: The Sutherland-Hodgeman algorithm is not ABLE to produce connected areas. For connected areas, Weiler-Atherton Algorithm is USED.

Right answer is (B) 180

Easy explanation: A convex polygon is a SIMPLE polygon in which no line segment between TWO points on the boundary ever goes outside the polygon and interior angles are less than 180 degrees.

Right OPTION is (d) bottom edge

Easiest explanation: If we USED Left->Right->Up->Bottom, the final output will be the vertex list outputted by the bottom edge. The final RESULT is GIVEN by the last edge which is a bottom edge in this case.

The correct option is (a) True

Explanation: If the subject POLYGON was CONCAVE at vertices OUTSIDE the clipping polygon, the new polygon may have COINCIDENT edges. The result will be the same in case of overlapping edges too.

The correct option is (d) 4

Explanation: If the ALGORITHM is done in 2D, we have 4 EDGES of the clipping area. Left edge, right edge, TOP edge and bottom edge.

Right option is (c) window edge

The EXPLANATION is: We can correctly CLIP a polygon by PROCESSING the polygon boundary as a whole against each window edge which can be ACCOMPLISHED by processing all polygon vertices against each rectangle.

Right ANSWER is (c) 2

For EXPLANATION: Two polygons are USED in this algorithm NAMELY CLIP polygon and subject polygon.

The correct choice is (d) VISIBLE SIDE

To elaborate: Only vertices from the SUBJECT polygon which are on the visible side are selected and rest of the vertices are CLIPPED.

Right choice is (b) False

The explanation is: Fast clipping ALGORITHM has similarities with Cohen–Sutherland. The start and end POSITIONS are CLASSIFIED by which portion of the 9-area grid they occupy, in both of the ALGORITHMS.

Correct choice is (c) line

Easiest EXPLANATION: Line clipping is the process of removing LINES or portions of lines outside an area of INTEREST and fast clipping ALGORITHM is an example of line clipping algorithm.

The correct CHOICE is (d) CONVEX

To explain: The polygon is ASSUMED to be convex and VERTICES are ordered clockwise or anti-clockwise while applying line clipping algorithms. Anti-convex polygons are not used.

Correct choice is (a) PROJECTIVE plane

Explanation: A plane duality is a map from a projective plane C = (P, L, I) to its DUAL plane C∗ = (L, P, I); which PRESERVES INCIDENCE.

Correct option is (B) False

The explanation: SKALA is SIMPLE and easy to implement whereas O algorithm SHOWS run time complexity.

The CORRECT answer is (a) Lg N algorithm

Explanation: ANOTHER name of O algorithm is Lg N algorithm. This algorithm CLASSIFIES vertices against the given line in the implicit FORM p: ax + by + c = 0.

The correct option is (b) SKALA

To ELABORATE: Skala can be used for a line or line-segment CLIPPING against a rectangular window, as WELL as against a convex polygon.

The correct choice is (a) SKALA

For EXPLANATION: Skala is a METHOD of clipping whose algorithm is based on HOMOGENEOUS coordinates and DUALITY.

Correct CHOICE is (b) False

Easy EXPLANATION: The regions are determined by the property that, no matter where in the region the second point (endpoint) is, the SEGMENT will have to be intersected with the same BOUNDARIES of the window.

The correct answer is (B) TR

To ELABORATE: R – RAY intersects right boundary; TR – ray intersects top and right boundary.

The correct OPTION is (b) initial points

To EXPLAIN: These AREAS are then DESIGNATED as L, LT, LB, or TR, depending on the location of the initial point.

The correct option is (B) T

For explanation I would SAY: T – ray intersects TOP BOUNDARY; LT – ray intersects left and top boundary.

The correct answer is (a) 3

The best EXPLANATION: The INITIAL point should be in THREE predetermined areas; so that the line MAY have to be translated or rotated to bring it into the desired REGION.

Correct OPTION is (b) False

Explanation: The Nicholl–Lee–Nicholl algorithm is a fast line CLIPPING algorithm that reduces the chances of clipping a single line SEGMENT MULTIPLE times.

Correct answer is (a) more

The EXPLANATION: ONE of the PROBLEMS common to both the Cohen-Sutherland and the Liang-Barsky ALGORITHM is that more INTERSECTIONS are computed than necessary.

Right OPTION is (d) Nicholl-Lee-Nicholl algorithm

The BEST I can explain: The full FORM of NLN clipping algorithm is Nicholl-Lee-Nicholl algorithm. It is a fast METHOD of clipping.

The correct CHOICE is (d) 4

To explain I would say: Liang-Barsky line clipping algorithm SOLVES 4 inequalities to find the range of the parameter for which the line is in the intersection with the rectangle.

Correct choice is (c) pk = 0

The EXPLANATION: When pk < 0 line starts exceeding the boundary while if pk > 0 line is BOUNDED inside the boundary. When the line is PARALLEL then pk = 0.

Right option is (a) True

To ELABORATE: Liang–Barsky clipping algorithm does as much TESTING as possible before computing line intersections, hence it is much more efficient than OTHERS.

The correct option is (a) Cyrus BECK ALGORITHM

The explanation is: The ideas for clipping line of Liang-Barsky and Cyrus-Beck are the same. The only difference is Liang-Barsky algorithm has been optimized for an UPRIGHT rectangular clip window.

Right choice is (b) OR

Easiest EXPLANATION: The logical OR of the ENDPOINT codes determines if the line is COMPLETELY inside the window. If the logical OR is zero, the line can be trivially ACCEPTED. For example, if the endpoint codes are 0000 and 0000, the logical OR is 0000 – the line can be trivially accepted.

The correct CHOICE is (c) LINE

The explanation: Liang–Barsky ALGORITHM is a line clipping algorithm. The Liang–Barsky algorithm uses the PARAMETRIC equation of a line for clipping OPERATIONS.

Correct answer is (a) 1001

To explain I would say: The sequence for READING the CODES’ bits is LRBT (Left, Right, BOTTOM, Top). SINCE it is in the top-left corner of the window, hence its code will be 1001.

Right answer is (C) completely inside

To explain I WOULD say: To perform the trivial ACCEPTANCE and rejection TESTS, we extend the edges of the window to divide the plane of the window into the nine regions. If both codes are 0000 and 1111, (bitwise OR of the codes YIELDS 0000) line lies completely inside the window and outside the window respectively.

The correct choice is (a) 0000

The best explanation: In any co-ordinate system, the origin is the centre of the various axis and is represented as (0,0). So in this CASE ALSO the origin, or the centre of the WINDOW, will be represented as 0000.

Right OPTION is (b) OUTCODE

The explanation: A small integer holding a BIT for the result of every PLANE test failed in clipping is termed as outcode. Primitives may be trivially rejected if the bitwise of all its vertices OUTCODES is non zero.

The correct ANSWER is (a) 4,6

To elaborate: The outcode will have 4 bits for two-dimensional CLIPPING, or 6 bits in the three-dimensional case. The first BIT is set to 1 if the point is above the VIEWPORT. The bits in the 2D outcode represent: top, bottom, right, left.