3DSur 3-dimension surface plotting documentation. ------------------------------------------------ 3DSur is a program for plotting surfaces of 2 variables z = f(x,y). There are some already built in functions, you can see the program plot these functions by changing different parameters or you can enter your own function. Be careful that the function must by defined every where on the rectangular region that you want to plot. Requirements: IBM XT, AT or compatibles 128K RAM and CGA. You can always back up one level by pressing ESC key at any time (or almost). When the program ask if you want to print or to save the program and you answered yes but then you change your mind, you can always enter "quit" for the file name or press ESC for the print mode to get out. There are several mode of plotting a function, here are a brief description for each of them. (For more details, you have to try out them yourself). H,D,N: Hidden line removal, means the part that is not visible will not be visible on the screen. They are different algorithms. H: My own algorithm, it plots from far to near and erase in between curves. D: An algorithm already exits, however I did enhance it by adding the cross section plotting. N: The previous algorithms as it is, implemented in Pascal. (see ref) P: Polar coordinate, use R-Th sections rather than the x-y sections. F: Fast cartesian coordinate, it is faster than the cartesian method of plotting, however, you have less control over it, like the number of points per curve and number of curves per surface, the program will take the average of these two. C: Cartesian plotting, it is slower then the previous one, however you can adjust the number of curves per surfaces in both sections, and how smooth the curves are. S: The program will paint the surface, it will simulate the hidden line one as in 'H'. None of the hidden line algorithm here is perfect. However, it one doesn't work, you can try others, later version of this program will improve this. While plotting, you can press the upper or lower arrow keys to change the colors, if your monitors can recognize the different color signals you should get 15 colors. scale_factor: is the number of points to calculate to determine the rescale the image so that it will fit into the display area. The larger the scale_factor, the accurate is the scaling, however if you know the graph does not change radicaly in the interval, you can set a lower scale factor to speed things up. Here are some descriptions about the viewing parameters. rot: angle between the x-axis and the projection of the vector "OP" in 3-D onto the x-y plane, correspond to left-right rotation. Where OP is the vector joining the origine and the viewing point P. tilt: angle between the vector OP and the z-axis, correspond to the up-down rotation of the graph. rho: distance between the view point P and the origine, where the origine can be consider as the viewing object also. dist: distance between the view point P and the projection screen. xmin, xmax, ymin, ymax: the rectangular area, that is the subset of the domain of the function that you want to plot the function over. #Secn: number of curves per surface, the larger the number more dense the graph is. Pts/Secns: number of segment used to approximate the curve, the larger the number, the smooth the curve is. You can load and save and print a picture, to save and print a picture you must draw it first. To load a picture, select the load option from the main menu. PrintMode (only support Epson printers) 0: 640 points/line (Epson mode 4) 1: 960 points/line (Epson mode 1) 2: 960 points/line (Epson mode 2) 3: 1920 points/line (Epson mode 3) 4: 720 points/line (Epson mode 6) Words of thanks and references. Most of the screen layout is from the Merlin program for the IBM PC together with the polar coordinate plotting method. The person that wrote these routine is prof P.J Ponzo of University of Waterloo (Applied Math Department) The hidden line routine and the cartesian method is from the book "Microcomputer Graphics for the IBM PC" by Roy E.Myers. This book is very simple and readable for beginners on graphics. The screen loading, screen saving, screen printing routines are from Borland's Graphix Toolbox for Turbo Pascal. Lastly I want to thank Jimmy Lee who let me use his hardwares for the development of this program. If you find this program useful, please consider a contribution in whatever amount that you feel is appropriate. Any comments, suggestions are welcome, also if there's any bugs please send them by writing to Mr. Duy-Minh NHIEU 4882 Mackenzie Montreal Quebec Canada H3W-1B3 Sourse code in Turbo Pascal available for a charge of $50 U.S. You are encouraged to copy and distribute 3DSur and its related files and charge no fee of any kind. Freely freely you have received, freely freely give!