Home  |  Forums  |  914 Info  |  Blogs
 
914World.com - The fastest growing online 914 community!
 
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG. This site is not affiliated with Porsche in any way.
Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners.
 

Welcome Guest ( Log In | Register )

2 Pages V  1 2 >  
 Reply to this topicStart new topic
> OT: Math Question ...
SirAndy
post Dec 30 2004, 11:21 PM
Post #1


Resident German
*************************

Group: Admin
Posts: 41,607
Joined: 21-January 03
From: Oakland, Kalifornia
Member No.: 179
Region Association: Northern California
stupid question (what else is new) ...

while working on my 3D-Editor/Game Engine i came to realize that the default Rotation Matrix for OpenGL uses a counterclockwise winding for Rotations around the Y-Axis (Yaw), meaning if you look at a Object in the XZ Plane a Positive Angle will Rotate the Object Left, a Negative Angle will Rotate it Right.

This is Counter-Intuitive and i am wondering if there is a rule for this behavior in a Cartesian coordinate system or is this merely a "personal preference" for OpenGL ???

My editor currently uses the clockwise approach, where a positive angle rotates the object to the right instead, which seem much more intuitive.

searching the web, i have found both approaches, but i would like to know if there's a "corret" way to do it ...

(IMG:http://www.914world.com/bbs2/html/emoticons/type.gif) Andy
User is online!Profile CardPM
Go to the top of the page
+Quote Post
dinomium
post Dec 30 2004, 11:32 PM
Post #2


Git on a chair son, all the good stuff is goin over yer head!
****

Group: Benefactors
Posts: 2,777
Joined: 2-January 03
From: Bremerton, WA
Member No.: 74
Region Association: Pacific Northwest
polar coordiantes are mesured anti clockwise...
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
SirAndy
post Dec 30 2004, 11:44 PM
Post #3


Resident German
*************************

Group: Admin
Posts: 41,607
Joined: 21-January 03
From: Oakland, Kalifornia
Member No.: 179
Region Association: Northern California
QUOTE (dinomium @ Dec 30 2004, 09:32 PM)
polar coordiantes are mesured anti clockwise...

alright, so this would be the correct matrix then:

cos(angle)0sin(angle)
010
-sin(angle)0cos(angle)



hmmmm, maybe i will just make it an option for the enduser ...
(IMG:http://www.914world.com/bbs2/html/emoticons/idea.gif) Andy
User is online!Profile CardPM
Go to the top of the page
+Quote Post
dinomium
post Dec 31 2004, 01:00 AM
Post #4


Git on a chair son, all the good stuff is goin over yer head!
****

Group: Benefactors
Posts: 2,777
Joined: 2-January 03
From: Bremerton, WA
Member No.: 74
Region Association: Pacific Northwest
two quotes for you:
Chevy Chase as President Ford "It was my understanding there would be no math..."
or
Malibu Barbie "Math is Hard!"

(IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) either way that is just more trig than I care to remember... and not this close to new years!!
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
swood
post Dec 31 2004, 01:14 AM
Post #5


Senior Member
***

Group: Members
Posts: 1,839
Joined: 6-February 03
From: Strong Beach
Member No.: 251
Region Association: None
Shoot. I thought this was going to be one of those impossible to solve problems about two trains leaving at the same time travelling towards each other at different speeds. (IMG:http://www.914world.com/bbs2/html/emoticons/blink.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Gint
post Dec 31 2004, 01:27 AM
Post #6


Mike Ginter
***************

Group: Admin
Posts: 16,066
Joined: 26-December 02
From: Denver CO.
Member No.: 20
Region Association: Rocky Mountains
Looks like A.f.d bait to me... (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Trekkor
post Dec 31 2004, 02:55 AM
Post #7


I do things...
*****

Group: Members
Posts: 7,809
Joined: 2-December 03
From: Napa, Ca
Member No.: 1,413
Region Association: Northern California
I was hoping this was some sort of game with a fake prize. (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif)

KT
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Steve Thacker
post Dec 31 2004, 07:01 AM
Post #8


UMMMPH Yea Baby Yea ! UMMMPH
***

Group: Members
Posts: 1,089
Joined: 8-January 03
From: Pickerington, Ohio
Member No.: 113
Region Association: Upper MidWest
That's some deep doo-doo Andy..... you flipping developers kill me. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

Sounds like the rare matting call to attract Alfreds.

Almost like Jennette MacDonald and Nelson Eddy I'm calling yooooo hoooo (IMG:http://www.914world.com/bbs2/html/emoticons/w00t.gif)


Sorry Andy I couldn't resist (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Red-Beard
post Dec 31 2004, 07:12 AM
Post #9


"Ya canna change the laws of Physics"
***

Group: Benefactors
Posts: 1,124
Joined: 11-February 03
From: Houston, TX
Member No.: 288
Region Association: None
QUOTE (swood @ Dec 30 2004, 11:14 PM)
Shoot.  I thought this was going to be one of those impossible to solve problems about two trains leaving at the same time travelling towards each other at different speeds.  :blink:

_YOU_ are the engineer on a train traveling from New York City to Chicago...

Yeah, Standard Polar coordinates are counter clockwise. And they were derived from Standard Carteasean coordinates.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ChrisFoley
post Dec 31 2004, 07:32 AM
Post #10


I am Tangerine Racing
*****

Group: Members
Posts: 7,911
Joined: 29-January 03
From: Bolton, CT
Member No.: 209
Region Association: None
Think of it this way: in an xy plot of a ray beginning at the origin, as the slope increases from zero to ninety degrees (and beyond) - the ray rotates in a counterclockwise direction.
Everything else follows from this example.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
rick 918-S
post Dec 31 2004, 08:24 AM
Post #11


Hey nice rack! -Celette
***************

Group: Members
Posts: 20,427
Joined: 30-December 02
From: Now in Superior WI
Member No.: 43
Region Association: Northstar Region
What some people solve with math others would solve with a hammer. Hit the coil until you loosen the wires. Then wind them the other way. This should achieve what your after without changing the math. (IMG:http://www.914world.com/bbs2/html/emoticons/happy11.gif)
User is online!Profile CardPM
Go to the top of the page
+Quote Post
Curvie Roadlover
post Dec 31 2004, 08:39 AM
Post #12


Two trunks are better than one!
****

Group: Members
Posts: 2,025
Joined: 29-December 02
From: Southeast Michigan
Member No.: 42
Maybe there's someone out there that could post some scanned articles from old Road and Track issues to explain this (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/alfred.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
michel richard
post Dec 31 2004, 10:24 AM
Post #13


Senior Member
***

Group: Members
Posts: 1,291
Joined: 22-July 03
From: Longueuil, Québec
Member No.: 936
QUOTE (rick 918-S @ Dec 31 2004, 06:24 AM)
What some people solve with math others would solve with a hammer. Hit the coil until you loosen the wires. Then wind them the other way. This should achieve what your after without changing the math. (IMG:http://www.914world.com/bbs2/html/emoticons/happy11.gif)


Th best quote in a long, IMHO.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
john rogers
post Dec 31 2004, 10:36 AM
Post #14


Senior Member
***

Group: Members
Posts: 1,525
Joined: 4-March 03
From: Chula Vista CA
Member No.: 391
I teach a couple of graphics classes using OpenGL and somethings are not really sensible to us normal people?! Try this website as there are many really good tutorials and explanations: http://nehe.gamedev.net/
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
KaptKaos
post Dec 31 2004, 10:40 AM
Post #15


Family
****

Group: Members
Posts: 4,009
Joined: 23-April 03
From: Near Wausau
Member No.: 607
Region Association: Upper MidWest
"It's a farging trick question!" - Roman Maronie
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Bruce Allert
post Dec 31 2004, 10:43 AM
Post #16


Hellions asleep
****

Group: Members
Posts: 3,289
Joined: 19-March 03
From: Eagle Creek, Orygun
Member No.: 441
Region Association: Pacific Northwest
/ v <=> b:© + h(M)

/ angle
v dangle
<=> proportional to
b: beauty of
c cutie
h heat
m meat


(IMG:http://www.914world.com/bbs2/html/emoticons/cool_shades.gif) .........einstein (IMG:http://www.914world.com/bbs2/html/emoticons/alfred.gif)

.........b
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Sammy
post Dec 31 2004, 11:18 AM
Post #17


.
***

Group: Members
Posts: 1,190
Joined: 21-January 03
From: Orange, Ca
Member No.: 178
My cat's breath smells like cat food.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
sgomes
post Dec 31 2004, 12:05 PM
Post #18


Electric Member
***

Group: Members
Posts: 815
Joined: 6-May 04
From: Campbell, CA
Member No.: 2,029
As Homer said:

Y're all nuts. I'm goin' to Moe's.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
SirAndy
post Dec 31 2004, 01:54 PM
Post #19


Resident German
*************************

Group: Admin
Posts: 41,607
Joined: 21-January 03
From: Oakland, Kalifornia
Member No.: 179
Region Association: Northern California
QUOTE (Red-Beard @ Dec 31 2004, 05:12 AM)
Standard Polar coordinates are counter clockwise. And they were derived from Standard Carteasean coordinates.

that's what i wanted to know. the math is easy, just didn't know if there was a "right" way to do it.

counter-clockwise it is then ...

easy enough,
(IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) Andy

PS:
QUOTE
http://nehe.gamedev.net/
alreayd bookmarked for quite some time now ...

PPS:
QUOTE
My linear algebra is rustier than the "hell hole"
that's why i didn't ask you in first place, plus, you just can't seem to give an simple answer to a simple question ...
User is online!Profile CardPM
Go to the top of the page
+Quote Post
rick 918-S
post Dec 31 2004, 06:22 PM
Post #20


Hey nice rack! -Celette
***************

Group: Members
Posts: 20,427
Joined: 30-December 02
From: Now in Superior WI
Member No.: 43
Region Association: Northstar Region
QUOTE (SirAndy @ Dec 31 2004, 11:54 AM)


PPS:
QUOTE
My linear algebra is rustier than the "hell hole"
that's why i didn't ask you in first place, plus, you just can't seem to give an simple answer to a simple question ...

(IMG:http://www.914world.com/bbs2/html/emoticons/idea.gif) I still think it's easier to rewind the coil. (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)
User is online!Profile CardPM
Go to the top of the page
+Quote Post
« Next Oldest · 914World Garage · Next Newest »
 

2 Pages V  1 2 >
Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 

Display Mode: Standard · Switch to: Linear+ · Switch to: Outline

Track this topic · Email this topic · Print this topic · Subscribe to this forum

- Lo-Fi Version Time is now: 29th April 2024 - 11:41 AM
Invision Power Board v9.1.4 © 2024  IPS, Inc.
All rights reserved 914World.com © since 2002
914World.com is the fastest growing online 914 community!
We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ...