Ellipse generation algorithm - 2d shape primitives, Computer Graphics

Assignment Help:

Ellipse Generation Algorithm 

You know that a circle is symmetric in all the octants, while ellipse is symmetric with respect to four quadrants.  Therefore, to draw an ellipse, we need to determine approximating pixels in one quadrant.  We proceed exactly the same way as we did in the case of a circle.  Define a decision parameter and choose the next pixel position depending on the sign of the decision parameter. The decision parameter is defined in terms of the equation of an ellipse.   

As in the case of a circle, let us assume that the ellipse is having centre at the origin.  Consider its perimeter segment in the positive quadrant. Identify the point on the perimeter where the ellipse has tangent line with slope = -1. Then divide the positive quadrant in two regions- Region I where slope  dy/dx > -1  and Region II where slope dy/dx < -1  .  You may notice that for Region I,  y  values of points of the perimeter are decreasing slowly with respect to  x  values, than in Region II.  This means for determining the approximating pixels, we have to do the following.  For each increment in  x  value,  y  will either remain same or be decremented depending on the sign of a decision parameter.  But in Region II, for each decremented  y  value,  x  will either be incremented or will remain the same (compare with two cases of Bresenham line drawing algorithm for slopes  | m | <  1 and   | m | > 1).


Related Discussions:- Ellipse generation algorithm - 2d shape primitives

Design and functioning of a refresh cathode ray tube, Design and functionin...

Design and functioning of a refresh cathode ray tube Primary components of refresh cathode ray tube are (i) electron gun used in producing electron beam (ii) heating fila

What are the different types of parallel projections, What are the differen...

What are the different types of parallel projections?  The parallel projections are basically divided into two types, depending on the relation among the direction of projectio

Determine how many key frames does one minute animation film, How many key ...

How many key frames does one minute animation film order along with no duplications need if there are five in among for each pair of key frames?   Solution : One minute = 60 sec

Object oriented tools, Object Oriented Tools: In such authoring systems, m...

Object Oriented Tools: In such authoring systems, multimedia components and events turn into objects that live in hierarchical order of parent and child relations. Messages are pa

Curves and surfaces - modeling and rendering, Curves and Surfaces - Model...

Curves and Surfaces - Modeling   and Rendering We have studied the method of drawing curves in diverse coordinate systems. Also we got the concept that it is the revolution of

Fixed point scaling, what is fixed point scaling? how composit transformati...

what is fixed point scaling? how composit transformation techniques works on it

Storing information structures in display memory, What is the major disadva...

What is the major disadvantages of storing information structures in display memory? A major disadvantage of storing information structures in display memory is that when color an

Computer aided design and drafting, Computer Aided Design and Drafting ...

Computer Aided Design and Drafting CADD or CAD stands for Computer Aided Design and Drafting. This is different from both "draw" and "paint" programs in which measurement is c

Scenes - polygon rendering and ray tracing methods, Scenes - polygon render...

Scenes - polygon rendering and ray tracing methods In the context of ray tracing, a scene is a set of objects and light sources which will be viewed through a camera. All of

State the advantages and disadvantages of CAD, State the Advantages AND Dis...

State the Advantages AND Disadvantages of CAD       Advantages of CAD                                                               Disadvantages of CAD - Easier to modif

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd