Cases of the sutherland hodgman polygon clipping algorithm, Computer Graphics

Cases of the Sutherland Hodgman Polygon Clipping Algorithm

In order to clip polygon edges against a window edge we move from vertex Vi to the subsequent vertexVi+1 and choose the output vertex as per to four simple tests or rules or cases listed here in below:

Table: Cases of the Sutherland-Hodgman Polygon Clipping Algorithm

Case

Vi

Vi+1

Output Vertex

A

Inside window)

Inside

Vi+1

B

Inside

Outside

V'i   i.e  intersection of polygon and window edge

C

Outside

Outside

None

D

Outside

Inside

V'I  ; Vi+1

Conversely, the 4 possible Tests listed above to clip any polygon conditions are as mentioned here:

1) If both Input vertices are within the window boundary then only second vertex is added to output vertex list.

2) If first vertex is within the window boundary and the 2nd vertex is outside then, merely the intersection edge along with boundary is added to output vertex.

3) If both Input vertices are outside the window boundary then nothing is added to the output list.

4) If the first vertex is outside the window and the 2nd vertex is within window, then both the intersection points of the polygon edge along with window boundary and second vertex are added to output vertex list.

Here, we can utilize the rules cited above to clip a polygon properly. The polygon should be tested against each edge of the clip rectangle; new edges should be added and existing edges must be discarded, retained or divided. In fact this algorithm decomposes the problem of polygon clipping against a clip window in the same sub-problem where a sub-problem is to clip all polygon edges that is pair of vertices in succession against a particular infinite clip edge. The output is a set of clipped edges or pair of vertices which fall in the visible side along w.r.t. clip edge. Such set of clipped edges or output vertices are taken as input for the subsequent sub-problem of clip against the second window edge. Hence, identifying the output of the earlier sub-problem as the input, all of the sub-problems are solved in sequence, at last yielding the vertices which fall on or inside the window boundary. These vertices linked in order forms, the shape of the clipped polygon.

Posted Date: 4/3/2013 3:48:19 AM | Location : United States







Related Discussions:- Cases of the sutherland hodgman polygon clipping algorithm, Assignment Help, Ask Question on Cases of the sutherland hodgman polygon clipping algorithm, Get Answer, Expert's Help, Cases of the sutherland hodgman polygon clipping algorithm Discussions

Write discussion on Cases of the sutherland hodgman polygon clipping algorithm
Your posts are moderated
Related Questions
Archeology: along with the advent of the computer, the archeologist has obtained a new tool, computer animation. An object-model can be made comparatively quick and without any we

QUESTION (a) People want to know design patterns. i) What should their attitude be about design patterns? ii) How can people use design patterns to do a better job?

Question 1 Explain any ten types of artistic filters Question 2 What is Freehand Tool? Explain the procedure of drawing lines and curves with freehand tool Question 3 Ho

Audio File Formats: It is a container format for storing audio data in a computer system. Many file formats are there for storing audio files. The common approach towards

Find Out Projection Matrix for Oblique Projection To find out projection matrix for oblique projection, we want to find out the direction vector d. Because vector PP' and vect

Assumption regarding to the Digital Differential Analyzer Algorithm The line generation by DDA is discussed merely for the first Quadrant, whether the line lies in the other q

Determine the transformation matrix for: a) Cavalier projection with θ=45 0 , and b) Cabinet projection with θ=30 0    c) Draw the projection of unit cube for all transfor

Write a code to continuously rotate a square about a pivot point.    #include   static GLfloat rotat=0.0;   void init(void); void display(void); void reshape(int w

Explain Three Dimensional Transformations A 3D geometric transformation is utilized extensively in object modelling and rendering. 2D transformations are naturally extended to

I am trying to do a project by matlab. which is related to computer vision. the name of project is (texture synthesis and image quilting), which is inspire from this paper (Efros a