# Category : Science and Education

Archive : 3DSURFAC.ZIP

Filename : 3DSUR.DOC

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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!

Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!

This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.

But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/