fractal3.cxx:This should be a modified version of the fractal.cxx program which you can download from www.cs.colorado.edu/~main/chapter9/fractal.cxx. The original file displays a 2d fractal surface. Your modified version will display a 3d fractal surface as described below. The main program must display this surface and then allow the user to move the viewpoint around the surface.
priority.h:A priority queue class that you'll need for the three-d graphics file in this assignment.
useful.h:A small collection of useful functions such as a function to generate a random real number in a specified range.
threed.h and threed.c:
Xturbo.h and Xturbo.c:These files provide the Polygon data type that you can use to display a collection of polygons in 3-d space.
test3d.cxx:A small demonstration program for the stuff in threed.h. Make sure you know how to compile and run this before you do anything else.
Start by grabbing fractal.cxx, renaming it to fractal3.cxx, and changing the include files at the top to be the old include files (assert.h, stdlib.h, and iostream.h). Delete the using namespace directive too because we're going to have to use a slightly older compiler.
Then write a new prototype for the random_fractal function that would be approprite for a three-dimensional surface rather than a simple line. The information that you pass to the new random_fractal function must include the x and y coordinates of the four points of a square on the x-y plane along with four heights (one for each of the four corners of the square). You should think a bit about how to pass all that information to the random_fractal function. For example: Do you need to pass four separate x-coordinates for the four corners of the square, or can you get by with less?
As with the original 2-D version, you will also have an epsilon parameter to indicate when the recursion stops. (My implementation stops when the width of my square drops below epsilon. I calculate the width by subtracting one x-coordinate from another rather than passing an explicit width parameter. But you could also pass it as a parameter if you prefer.)
After you have written your new prototype, add that to your fractal3.cxx file along with a comment that indicates what the new function will do.
Then, of course, you need to implement the function:
Polygon *p = new Polygon; ...followed by four calls to p->AddVertexXYZ(...);Once the Polygon is created, you don't need to worry about it any more.
E A-----------------B | | | | | | | | | | | | H|-------+-------|F | I| | | | | | | | | | | D-----------------C GIn this drawing, the original four points given as parameters to the random_fractal function are A, B, C and D. You will have to calculate the coordinates of the five other points (E, F, G, H and I). Use a straight-line interpolation to calculate these points. For example, the z-coordinate of point E should be calculated as halfway between the z-coordinate of A and the z-coordinate of B. Once you have calculated the coordinates of the five extra points, you should then move point I up or down a random amount before making any recursive calls.
Notice that there will be four recursive calls in all. For example, one of the four recursive calls will deal with the upper-left sub-square A-E-I-H.
Once you have the random_fractal function in place, you should modify the main program so that it does these things:
RefreshScreen( ). This will display all the polygons that you created.
ShutDownGraphicsand then leave the loop), to zoom in or out (use the
threed.h, and to rotate the view around the origin using
threed.h. Each time that you change the screen, call
RefreshScreento redraw everything.
Compiling, Linking, Running
Do all your compilation and running on one of the bird machines (just like the polycgi assignment). A list of these machines is given at the bottom of http://csel.cs.colorado.edu/udp/machines.html. The compilation can be done from any kind of login on one of these machines. But for the actual running, you must establish an X connection. An X-connection can be established from any machine in the undergrad lab with the slogin command. For example, to connect to swallow:
When you compile, you must make and link together these files:
makefileand make sure that each command line begins with a tab (not with eight spaces).