1. What is an output primitive?
Graphics programming packages provide function to describe a scene in terms of these basic geometric structures, referred to as output primitives.
2. What do you mean by ‘jaggies’?
Line with stair step appearance is known as jaggies.
3. What is point in the computer graphics system?
The point is a most basic graphical element & is completely defined by a pair of user coordinates (x , y).
4. Write short notes on lines?
A line is of infinite extent can be defined by an angle of slope . and one point on the line P=P(x,y). This can also be defined as Y=mx+C where C is the Y- intercept.
5. Define Circle?
Circle is defined by its center xc, yc and its radius in user coordinate units. The equation of the circle is (x-xc) + (y-yc) = r2.
6. Define Ellipse?
An ellipse can use the same parameters xc, yc ,r as a circle, in addition to the eccentricity e. the eqn of an ellipse is: (x-xc)2/a2 + (y-yc)2/b2 = 1
7. Define polygon?
A polygon is any closed continues sequence of line segments ie, a polyline whose last node point is same as that of its first node point. The line segments form the sides of the polygon and their intersecting points form the vertices of the polygon.
8. Distinguish between convex and concave polygons?
If the line joining any two points in the polygon lies completely inside the polygon then, they are known as convex polygons. If the line joining any two points in the polygon lies outside the polygon then, they are known as concave polygons.
9. What is seed fill?
One way to fill a polygon is to start from a given point (seed) known to be inside the polygon and highlight outward from this point i.e neighboring pixels until encounter the boundary pixels, this approach is called seed fill.
10. What is scan line algorithm?
One way to fill the polygon is to apply the inside test. i.e to check whether the pixel is inside the polygon or outside the polygon and then highlight the pixel which lie inside the polygon. This approach is known as scan-line algorithm.
11. Define coherence properties?
A coherence property of a scene is apart of a scene by which relate one part of the scene with the other parts of the scene.
12. What is an active edge list in the scan line algorithm?
The active edge list for a scan line contains all edges crossed by that scan line.
13. What is a winding number?
Winding number method is used to check whether a given point is inside or out side the polygon. In this method give a direction number to all the edges which cross the scan line. If the edge starts below the line and ends above scan line give direction as -1 . otherwise1. Fr polygons or two dimensional objects, the point is said to be inside when the value of winding number is nonzero.
14. What is cell array?
The cell array is a primitive that allows users to display an arbitrary shape defined as a two dimensional grid pattern.
15. What is type face?
Letters, numbers and other characters can be displayed in a variety of sizes and styles. The overall design style for a set of characters is called a type face.
16. What do you mean by font?
The term font referred to a set of cast metal character forms in a particular size and format, such as 10-point courier italic.
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