BBS: Inland Empire Archive Date: 03-17-92 (23:56) Number: 136 From: MARK KO Refer#: NONE To: BOB MURPHY Recvd: NO Subj: Re:3d Graphics Conf: (2) Quik_Bas

Technical? Well, I haven't seen this Torus program yet, but I can explain several methods of producing "3D" graphics. 1) You can use the method of casting shadows to produce 3D like graphics. For example, it you would look at a skeleton of a cube, it would appear, from the front, a square in a square. Everything in the background is just smaller if it can be seen. To use this method, a point must be chosen where the "light" will originate to cast a shadow. The formulas below well tell you how to calculate the new x,y coordinates. Xnew = (Xold*dis/(dis-Z)) Ynew = (Yold*dis/(dis-Z)) where dis is distance of light source from the object. You should do these conversions, before converting the coordinates to screen coordinates. 2) You can also have the computer calculate a sort of top view of a 3-D object. This can be done very easily. The angle of rotation (verticall0 must be known. Use the following equations. A = cos(angle), B=sin(angle) Xnew=Xold Ynew=(Yold*A - Zcoordinate*B) That's it. You might have to fool around with the angl to get the persepective you want. Remember, the angle can also be negative and it must be in radians. 3.141592654 radians = 180 degrees. 3) If you draw an X on the screen with a vertical line going through the middle of it, you will see three axes, X, Y, and Z. By the angle, that each axis makes with a horizontal line, a 3D object can be displayed. Use the following formulas to calculate the new coordinates. Xnew = Xold*cos(A) + Yold*cos(B) + Z*cos(C) Ynew = Xold*sin(A) + Yold*sin(B) + Z*sin(C) Where A is the angle of the X axis, B is the angle of the Y axis and C is the angle of the Z axis, all respective to a horizontal line and in radians. I hope this helps you in your program. P.S. if you wish to learn how to make stereoscopic drawings to create a draw three D effect, just ask. --- RBBSMAIL 17.2A * Origin: Computer Co-Op RBBS HST, 609-784-9404 Voorhees NJ (RBBS-PC 1:266/29)

Echo Basic Postings

**Books at Amazon:**

Back to BASIC: The History, Corruption, and Future of the Language

Hackers: Heroes of the Computer Revolution (including Tiny BASIC)

Go to: The Story of the Math Majors, Bridge Players, Engineers, Chess Wizards, Scientists and Iconoclasts who were the Hero Programmers of the Software Revolution

The Advent of the Algorithm: The Idea that Rules the World

Moths in the Machine: The Power and Perils of Programming

Mastering Visual Basic .NET