From: Ludvig Larsson Newsgroups: comp.os.msdos.djgpp Subject: Re: 3d sphere Date: Sat, 17 Oct 1998 05:57:23 +0200 Organization: Faas-Goldhart Lines: 35 Message-ID: <362815A3.6A2C@club-internet.fr> References: <703e0b$sts$1 AT supernews DOT com> NNTP-Posting-Host: toulouse-camichel5-132.club-internet.fr Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Trace: front5.grolier.fr 908596724 26039 195.36.147.132 (17 Oct 1998 03:58:44 GMT) NNTP-Posting-Date: 17 Oct 1998 03:58:44 GMT X-Mailer: Mozilla 3.01C-CLUB (Win95; I) To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp Reply-To: djgpp AT delorie DOT com jud wrote: > > i came up with an idea of the idea of making a program that will draw a > sphere out of a series of lines. This lines will be the size of the > perimeter of the sphere. There will be the same amount of these "ribbons" as > there are pixels in the hieght of the sphere. > > The problem here is i havent taken anything above algebra 1, although i have > some basic ideas about sine cosine and arctangent funtions. A problem arises > that if you take the half of the "ribbon" you have to make it shrink more > and more as it geos from the middle of the sphere around, i dont know the > formula to do this and i need it so i can show the sphere on the screen and > have it look realistic Phew... I'll guess that maybe I can give you a hint... If you are not speed dependen, make two loops: loop b=0° to 180° loop a=0° to 180° ribbon=cos(b) offset in ribbon=cos(a) screenpos= (a,b) offcourse you have to multiply a and b with different konstants, bependin on how many ribbons you have, how big they are and the size of the sphere on screen. cos(a) and cos(b) witt ossilate between -1 and 1 so if you want a screen x-size of 100, make screen_x=cos(a)*50+50; Hop it helped(and hope it works, BTW, ordinary sin() and cos() works with radians, radians=degrees*pi/180 so use sin(a*3.1415/180) etc). Ludvig Larsson