Hey, I''m working on a game that is like Tony Hawk''s Pro Skateboarder, only on a pogo stick. I think it will be hilarious, once I get it running. I''m having problems with some vector math. What I want to do is find the equation that use the angles from the axes and the magnitude to find the resulting vector in three dimensions. In two dimensions, it is easy, but three dimensions brings up a whole slew of problems. Any way, if anybody has any help they can give me it would be greeatly appreciated. Oh, and if anybody knows how I could speed up my computer, because it is old and slow, that would really help. I have a Compaq Presario with an AMD-K6 3d processor, 196 megs of ram, and I think the processor is running at 475 MhZ. Really slow, I know, so I was wondering what Graphics Card might be most compatible and helpful. Thanks! "Donkey, if it were me, you''''d be dead."

http://www.iancgbell.clara.net/maths/vectors.htm

You want the section on Spherical Polar coodinates.

Thanks for the link, but I''m having trouble understanding what each symbol meant. If I can tell correctly, you''re leaving out one of the rotations around the Y or X axis when changing from (rotationXorY, rotationZ, magnitude) = (x,y,z). If you can tell me how to use the equation in layman''s terms that would be greatly appreciated. I just got through Trig and hopefully next year we''ll cover the good stuff in Calculus. Maybe I''ll just have to wait for college.


"Donkey, if it were me, you''d be dead."

You only need 2 rotations.

Consider a point (1,1,1).

Project on xy plane and draw a right triangle (0,0), (0,1), (1,1). Base and height are both 1. 45 degree angle.

Project on xz plane and draw a right triangle (0,0), (0,1), (1,1). Also a 45 degree angle.

Finding that angle is a simple matter when you know that tan(angle)=opposite/adjacent. So angle=atan(opposite/adjacent).

So imagine you are sitting in a swivel chair at the north pole with a fishing pole exactly long enough to reach (1,1,1). Now start with the chair at 0 deg latitude and the pole pointing straight out at the horizon so it is 0 degrees. Now tilt your fishing pole up 45 deg (xy plane) then swivel the chair to 45 deg latitude (xz plane). There's your vector! Does that help?
You can use the xy and yz planes just as well, but you'll fall out of your chair and the reindeer will laugh and call you names.

[edited by - 5010 on June 7, 2003 8:58:14 AM]

Here''s a few sites with pictures that might help:
http://oregonstate.edu/dept/math/CalculusQuestStudyGuides/vcalc/coord/coord.html
http://mathworld.wolfram.com/SphericalCoordinates.html
http://www.math.grin.edu/~drayt/vectorcalc/coords.html

RtR

Thanks 5010, that really helped, although the reindeer still laughed when I tried to fish on the North Pole.

"Donkey, if it were me, you''d be dead."

quote:

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Original post by DuncanBojangles
Thanks 5010, that really helped, although the reindeer still laughed when I tried to fish on the North Pole.

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You''re welcome. Ice fishing is generally hazardous. You never know when some joker will come along and kick you in the ice-hole.