basic building blocks of raster graphics editor

Starting with the pixel position (xa, ya), we determine the offset needed at each step to generate the next pixel position along the line path. The difference with the greater magnitude determines the increment of the parameter steps. Horizontal & vertical differences between the endpoint positions are assigned to parameters dx & dy.

The algorithm accepts as input the two endpoint pixel positions. We sample the line at unit intervals in one coordinate & determine corresponding integer values nearest to the line path for the other coordinate. A minor extension to the original algorithm also deals with drawing circles.Īnother algorithm namely, Digital Differential Analyzer is a scan conversion line algorithm based on calculating either dy or dx. It is one of the earliest algorithms developed in the field of computer graphics. It uses only integer addition, subtraction and bit shifting where the digits are moved or shifted left or right, all of which are very cheap operations in standard computer architectures. In order to draw lines on a computer screen, the Bresenham line algorithm is used that determines which order to form a close approximation to a straight line between two given points. Algorithms are made for calculation, data processing and automated reasoning. In mathematics and computer science an algorithm is a step by step procedure for making calculations. The display processor read the data from the frame buffer and convert it into corresponding 1's and 0's according to there pixels and then put it on to a monitor screen.The display processor do this work 30 times per second to maintain a steady picture on the screen,and if we want to change the picture on the screen then we have to change the contents of frame buffer. This controls the view of the image so that the user can view the mage fromdesired angle and desired magnification. The memory can be discs, Integrated circuits etc., The image is stored in terms of pixel by pixel. The video output device which drives a video display from the memory buffer containing a complete set of data is known as frame buffer. The saved arrays usually take up far less disk space, but can the data can no longer be gated. The arrays are filled event by event from a list data in order to create a display. So often we want to handle polygon as a single entity, as images of objects from the real world consist in large, part of polygons.Ī display file is a set of uncorrelated data, such as a histogram array or bivariate array. Since images are two dimensional, a polygon is a closed planar figure.A polygon, is an important graphics primitive. A structural method determines which pixels should be set before drawing the line a conditional method tests certain conditions to find which pixel should be set next.Ī polygon is a closed area of image bounded by straight or curved lines and filled with one solid color. Straight lines can be developed in two different ways. In computer graphics, straight line is so basic in creating images that we call it a graphics primitive.

Line, especially straight lines, constitute the basic building block of Line graphs, bar and pie charts, two and three-dimensional graphs of mathematical functions, engineering drawings and architectural plans. Pixel ratio should be considered in line-generating algorithms. The ratio of the distance between the centres of two adjacent horizontal pixels to that of the vertical ones is called the pixel ratio. A resolution of 100 dots lines/inch implies a dot size of 0.01 inch. The resolution of CRT is related to the dot size, the diameter of a single dot. Though it has no structure, it is definitely a building block and hence it can be considered as the graphics primitive. It is just one tiny dot on the raster displays. The most basic of these elmental structures is the pixel, short for picture element.Ī pixel is a point of light. Graphics is constructed from three basic elements, as opposed to the great variety of graphics applications.

Graphics Primitive is a basic object that is essential for the creation or construction of complex images.

Basic building blocks of raster graphics editor