# Computer Graphics: Question Set – 06

#### Discuss explicit formula of line drawing.

A line is a collection of points that form a straight path. The line is often characterized by its two endpoints (x1, y1) and (x2, y2). The line drawing algorithm calculates intermediate points on the line.
Given the endpoints P1(x1, y1) and P2(x2, y2), every point P(x, y) on the line may be calculated using the slope-intercept formula:
The slope of the line is clearly shown in Figure.

The slope of the line is shown in Figure as

m = dy/dx

= (y2 – y1) / (x2 – x1)

Let c represent the line’s Y-intercept. Given an x coordinate, the value of the corresponding y coordinate of any point is calculated as follows:

y = mx + c

#### Enlist the properties of ideal line. Does line drawing algorithm generate same line?

An ideal line should have the following characteristics:

• It should interpolate both ends.
• The brightness of the line should be independent of the line’s orientation.
• It should be straight and smooth in appearance.
• It should be drawn as soon as possible.
• When we draw lines on paper, we satisfy all properties. However, when we rasterize it on the monitor, most of the properties are lost.
• Vertical and horizontal lines are presented with maximum intensity on the monitor screen; the brightness of inclined lines varies with orientation.

However, line drawing algorithms generates the line on discrete space on monitor. So the line on monitor screen would be different than the ideal line

#### Mention the different ways to represent the line.

The line can be depicted in a variety of ways. The following are the most typical representations:

Implicit representation: ax + by + c = 0

(x, y) is a point on a line, and a, b, c are line coefficients

Explicit representation: y = mx + c

(x, y) is the point on the line, m is the slope, and c is the Y-intercept.

Parametric representation:

x = x1 + (x2 – x1)t,

y = y1 + (y2 – y1) t

0 ≤ t ≤ 1.

(x1, y1) and (x2, y2) are line endpoints, and (x, y) is any point on line for any value of t. (x, y) = (x1, y1) for t = 0 and (x, y) = (x2, y2) for t = 1. We shall receive some intermediate point on the line for any other value of t.

#### List some applications where such types of monitor would be useful.

The following applications of various display technologies are listed:

• Raster scan display: These are utilized for animation and dynamic scene display
• Random scan display: These displays are used to portray complicated and static sceneries
• Interlaced display: Interlaced displays are beneficial in situations where the hardware does not support a higher refresh rate.
• CRT: CRT monitors were commonly used with older systems. until the invention of flat screens, CRT was the standard choice for desktop monitors and television sets.
• DVST: Can be used to portray complicated and static scenes. In DVST devices, there is no need to refresh.
• Plasma display: Suitable for displaying monochrome sceneries.
• Electroluminescent display: This type of display is useful in situations that require a limited range of colors and gray scales.
• LCD: Has a wider viewing angle and a greater resolution.
• LED: Less power consumption, lower cost, and higher resolution. Such displays are small in size, making them ideal for usage in offices and corporations.

#### Discuss General programming packages and Specials purpose application packages

General purpose programming packages: They are similar to programming languages in that they contain a diverse variety of graphical functions. Such graphics programs allow you to draw primitives, fill colors, adjust the intensity, and apply transformations, among other things. Such packages include Open GL and Open CV. They are more programmer-oriented and offer greater flexibility than special-purpose application packages. The use of such programs necessitates a high level of programming ability.

Special purpose application packages: Application graphics packages, on the other hand, are built for non-programmers so that users can produce appropriate visuals without thinking about underlying principles. The interface to graphics routines in such packages enables users to communicate with the applications in their own language. Such application packages include paint, CAD, and others. Such a package frequently includes a collection of drag-and-drop components, which relieves the user of the need to write code for basic building blocks.

#### Explain the concept of virtual reality

Virtual reality is a concept that attempts to simulate the real world. Virtual reality is an environment that duplicates the user’s expressions, feelings, and activities in such a way that the computer-generated synthetic world is perceived as real. Virtual reality is a simulator that employs computer graphics to create a realistic-looking, responsive virtual world. The user can interact with virtual world items, and the reaction to the user input is dynamically determined.

#### Define the term: Point

The smallest unit that we can address on the screen is the point or pixel. The scene’s basic unit is the point.

The coordinate pair (x, y) is used to define a point in the plane, whereas a triplet is used to define a point in space (x, y, z). Here, x and y are plane coordinates, while z is the distance between a point and the XY plane.

Scholarly Reading: Where do people draw line? Click to read