.nh
.po 5
.ce  
TEST 1 - CS458 
.nf 
Instructor Dr P Juell                   NAME_______________________ 
CLOSED BOOK                                        Sep 25, 1996
100 points         
                          This sheet is to be turned in with the test
.fi 

1. (20)
A $300 monitor can display 400 columns and 500 rows of pixels.
Each pixel can display any of 16 current colors.  The current colors
are selected from a pallet table.  Each entry in the pallet has 3 bits
for red (R), 3 for green(G) and two for blue(B).
A bigger version of the monitor works the same but has twice as many
rows and columns.
For the $300 monitor and the bigger monitor specify the number of 
BITS in: the frame buffer and the pallet.
You can leave expressions in forms like 2x3+4.
.nf
.in +5

	frame buffer			pallet

$300

bigger

.in -5
.fi

2. (15)
On a separate sheet is a VTK program.
.br
What does this program display?


Can you interactively fly through the image?


If you displayed in wire-frame mode, would there be:
.br
"MORE THAN" or "LESS THAN OR EQUAL TO" 15 endpoints of lines.


3. (15)
Specify a set of points and polygons in the form expected in vtk.
You are to specify a cube with each edge 2 units long.
.sp 10

4. (20)
Why is the Bresenham's line drawing routine more efficient than the
routine based directly on the formula for a line?
(note, there are several parts to this answer)
.sp 10

Give a good reason 
why you might still use the line drawing routine based directly on the 
formula for a line?
.sp 5
.bp

5. (20)
The following is a copy of Bresenham's line algorithm presented
in class.  One line is missing.  Specify that line.
.sp 
.nf
procedure bres_line(x1,y1,x2,y2: integer);
 var
   dx, dy, x, y, x_end, p, const1, const2: integer;
 begin
   dx := abs(x1 -x2);
   dy := abs(y1 -y2);
   p := 2 * dy - dx;
   const1 := 2 *dy;
   const2 := 2* (dy -dx);
   {determine which point to use as start, which as end}
   if x1 > x2 then begin
       x := x2; y := y2;
       x_end := x1
     end {if x1 > x2}
    else begin
      x := x1; y := y1;
      x_end := x2
     end; {if x1 <= x2}
    set_pixel(x,y);
    while x < x_end do begin
      x := x + 1;
				 <<<<<<<<<<<<<<<<missing line
      else begin
	y := y + 1;
	p := p + const2
       end; {else begin}
      set_pixel(x,y)
     end {while x < x_end}
end; {bres_line}
.fi

6. (10)
What is a "texture map" and how is it used?

.bp
.nf

#include "vtk.hh"
main ()
{
  char a;
  vtkRenderMaster renMaster;   // our required RenderMaster
  vtkRenderWindow *renWindow;  // a RenderWindow to draw in
  vtkRenderer *ren;            // a Renderer to do the drawing
  vtkActor *coneActor;         // an actor to be drawn
  vtkConeSource *cone;         // the model data for the actor
  vtkPolyMapper *coneMapper;
  
  // create a rendering window and renderer
  renWindow = renMaster.MakeRenderWindow();
  ren = renWindow->MakeRenderer();

  // create an actor and give it cone geometry
  cone = new vtkConeSource;
    cone->SetResolution(8);
  coneMapper = new vtkPolyMapper;
    coneMapper->SetInput(cone->GetOutput());
  coneActor = new vtkActor;
    coneActor->SetMapper(coneMapper);

  // assign our actor to the renderer
  ren->AddActors(coneActor);

  // draw the resulting scene
  renWindow->Render();

  // loop until key is pressed
  cout << "Press any key followed by <Enter> to exit>> ";
  cin >> a;
}

.bp
#include "vtk.hh"

main ()
{
  vtkRenderMaster rm;
  vtkRenderWindow *renwin;
  vtkRenderer *aren;
  vtkCamera   *camera1;
  vtkLight    *light1;
  vtkActor    *actor1;
  float foo = 0;
  vtkCubeSource *cube;
  vtkPolyMapper *mapper;
  
  renwin  = rm.MakeRenderWindow();
  aren    = renwin->MakeRenderer();

  cube = new vtkCubeSource(1,2,3);

  mapper = new vtkPolyMapper;
  mapper->SetInput(cube->GetOutput());

  actor1 = new vtkActor;
  actor1->SetMapper(mapper);
  actor1->GetProperty()->SetColor(.6,1.0,.8);

  light1 = new vtkLight;
  camera1 = new vtkCamera;

  renwin->AddRenderers(aren);
  aren->SetActiveCamera(camera1);
  aren->AddLights(light1);
  aren->AddActors(actor1);
  aren->SetBackground(0.2,0.2,0.2);

  camera1->SetPosition(10,8,5);
  camera1->SetFocalPoint(0,0,0);
  camera1->CalcViewPlaneNormal();

  /* make the light follow the camera */
  light1->SetPosition(camera1->GetPosition());
  light1->SetFocalPoint(camera1->GetFocalPoint());

  for (float l=1; l<10; l+=2)
    {
    cube->SetXLength(l);
    for (float yl=2; yl<12; yl+=2)
      {
      cube->SetYLength(yl);
      renwin->Render();
      }
    }
}