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TEST 1 - CS528 
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Instructor Dr P Juell                   NAME_______________________ 
OPEN BOOK                                        March 30, 1990
100 points         
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1. (30)
One way to draw curves is to approximate them with straight lines.
Contrast the following routine with the 
Bresenham circle routine.
(The bres_line routine is the Bresenham line algorithm in the book
extended for all slopes).
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procedure inter_circle(x_center,wy_center, radius: integer);
  var x_old, y_old, step, x, y : integer;

  procedure plot_circle_points(var x_old, y_old:integer; x, y: integer);
    procedure plot_line(x1, y1, x2, y2 :integer);
    begin
      bres_line(x1+x_center, y1+y_center,  x2+x_center, y2+y_center);
    end;
  begin
    plot_line( x_old, y_old,  x,   y);
    plot_line( x_old,-y_old,  x,  -y);
    plot_line(-x_old,-y_old, -x,  -y);
    plot_line(-x_old, y_old, -x,   y);
    x_old := x;
    y_old := y;
  end;
end;
begin
  x_old := 0;
  y_old := r;
  for step = 1 to 10 do
   begin
     x  :=  ( r * step) div 10; 
     y  := trunc(sqrt( r*r - x*x ) );
     plot_circle_points( x_old, y_old, x,  y);
   end; 
end;
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2. (10)
You are reading the specification for a CRT. The specifications
say it is a black and white display.
The frame buffer has 2 bits per pixel with lookup table entries of 8 bits.
What does this tell you about the display.

3. (20)
Show a line that incloses an area. 
Identify inside and the result of antialiasing area.
Also show the pixel subdivisions.
Correctly label one pixel for each of the values: 0%, 25%, 50%, 75% and 100%.

4. (20)
Write the statements (not a full program) to produce the following
image.  Use the GKS functions given up to now in the book.
       __________
       |        |
       | *-----*|
       | | NOW ||
       | |     ||
       | |_____||
       |________|

5. (20)
Write a routine that the book's fill_area_solid
routine can use to provide a patterned fill.  
Your routine is to be used instead of the point plot command.
The pattern will be
in the variable pat.  Its values are preset for you.

   var pat: array[1..4,1..4] of boolean;