Computer Graphics
Trivial Quiz 1
For each question circle ONE answer.
1. The general equation of a straight line is
(a) y = a + b + x
(b) a + b = x + y
(c) y = (a + b)x
(d) y = a + bx
(e) f(y,x) = f(a,b)
2. Bresenham's line drawing algorithm is needed
(a) because pixels are bigger than lines
(b) because lines are bigger than pixels
(c) to efficiently find the pixels corresponding to a line
(d) to compute the intersection between two lines
(d) to remove that part of a line that is outside the window
3. World coordinates are
(a) the coordinates in which lines are drawn
(b) an application dependent coordinate space
(c) coordinates that the whole world has to use
(d) coordinates for the whole screen
(e) coordinates for a viewport on the world of the screen
4. The window is mapped to the viewport in order to
(a) convert from world coordinates to display space
(b) reduce the window to the same size as the viewport
(c) reduce the viewport to the same size as the window
(d) achieve the effect of clipping
(e) make sure that every line is seen
5. In the Cohen-Sutherland line clipping algorithm, "trivial reject"
means
(a) that the intersection is trivial to compute
(b) that anyone can understand how to do rejection
(c) that the process of rejection is always trivial
(d) that the boundaries on the visible side of the line are incomplete
(e) that the line is not visible when its endpoints are on the invisible
side of a clipping boundary
6. The intersection of the boundary x = A with the line with endpoints
(x1,y1) and (x2,y2) is:
(a) (A,(dy/dx)(A-x1) + y1)
(b) y = A + bx
(c) ((dx/dy)(A-y1) + x1,A)
(d) ((dx/dy)(y-A1) + A1,x1)
(e) ((A/B)(x-x1) + A1,x1)
7. The algorithm to clip a polygon requires
(a) clipping of all its edges to all the clipping boundaries
(b) clipping of all the clipping boundaries to all the Outside polygon edges
(c) trivial rejection of its outside parts
(d) clipping of the polygon to each boundary in turn, passing the result
to the next boundary
(e) clipping of each polygon in turn to the boundary closest to its maximum
outside edge.
8. The polygon edge (5,1) to (1,5) would be represented in an Edge Table
for polygon scan conversion as the 3-tuple
(a) (1,5,1) into the row 1 of the edge table
(b) (5,1,-1) into the row 5 of the edge table
(c) (5,5,-1) into the row 1 of the edge table
(d) (1,5,-1) into the row 5 of the edge table
(e) (5,5,1) into the row 1 of the edge table.
9. Damage repair in computer graphics means
(a) Damaging parts of the output that lie outside the clipping region.
(b) Computing and redrawing parts of one object erased by changes to another
object.
(c) Moving an object in such a way that other objects are always visible.
(d) Repairing the display after someone has poured tea over the keyboard.
(e) Recomputing the fill area algorithm in the case when a polygon has only
horizontal edges.
10. The window is bounded by -1 <= x <= 1 and 0 <= y <= 1,
and the viewport is the square 0 to 1000 in each of x and y. The point (0,0)
in the window is which point in the viewport?
(a) (0,500)
(b) (0,0)
(c) (-1,0)
(d) (-1,500)
(e) (500,0)