Points and Lines - Graphic primitives
In the previous section, we have seen to draw primitive objects; one has to firstly scan convert the objects. This concern to the operation of determining the location of pixels to be intensified and then sets the values of consequent bits to the desired intensity level. All pixels on the display surface have a fixed size depending upon the screen resolution and thus, a pixel cannot characterize a single mathematical point. Conversely, we consider all pixels as a unit square area known through the coordinate of its lower left corner and the cause of the reference match system being located at the integer coordinate pair (x, y). The x values start at the origin and rise from left to right along a scan line and the y values that is the scan line numbers begin at bottom and raise upwards.
Figure: Scan lines
This demonstrates the Array of square pixels upon the display surface. Coordinate of pixel A: 0, 0; B: 2, 2; C: 6, 7. A coordinate position (6.26, 7.25) is characterized via C, while (2.3, 2.5) is demonstrated via B. As in order to plot a pixel on the screen we required to round off the coordinates to a nearest integer. Moreover, we require saying that, this is this rounding off, that leads to distortion of any graphic pattern.