Solved

Rotatating line... Linear Algebra question.

Posted on 2004-03-29
3
280 Views
Last Modified: 2013-12-26
Okay so here's a question. I need an algorithm for rotating a point (p2) about an axis (p1). Here's the spaghetti code I have so far.

Radius = SquareRoot((p2.y - p1.y) ^ 2 + (p2.x - p1.x) ^ 2)
Radians = ArcCos((p1.y - p2.y) / radius) ' Angle between Vector(p1,p2) and unit vector (p1, {0, 1}). Rotating counter clockwise.
Radians = Radians + (2 * ((2 * PI) / 360)) 'Add two degrees to current angle of line
p2.y = (Cos(Radians) * Radius) + p1.y
p2.x = (Cos(Radians) * Radius) + p1.x

The code works fine for angles < 180 degrees. But as soon as I get to say 182 the line moves to an angle of 2 degrees counter clockwise from the unit vector... anyone know a better algorithm for this or how to fix this one to be able to run a full rotation? I need to be able to "add" angles to lines.
0
Comment
Question by:CyrexCore2k
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
3 Comments
 
LVL 84

Expert Comment

by:ozo
ID: 10709272
Radians = atan2(p2.y - p1.y,p1.x - p2.x);
0
 
LVL 84

Accepted Solution

by:
ozo earned 125 total points
ID: 10709418
Radians = atan2(p2.y - p1.y,p2.x - p1.x)

 p2.x = (Sin(Radians) * Radius) + p1.x
0
 
LVL 14

Author Comment

by:CyrexCore2k
ID: 10709644
YES! Thank you!
0

Featured Post

Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

As game developers, we quickly learn that Artificial Intelligence (AI) doesn’t need to be so tough.  To reference Space Ghost: “Moltar, I have a giant brain that is able to reduce any complex machine into a simple yes or no answer. (http://www.youtu…
Performance in games development is paramount: every microsecond counts to be able to do everything in less than 33ms (aiming at 16ms). C# foreach statement is one of the worst performance killers, and here I explain why.
In an interesting question (https://www.experts-exchange.com/questions/29008360/) here at Experts Exchange, a member asked how to split a single image into multiple images. The primary usage for this is to place many photographs on a flatbed scanner…
How to Install VMware Tools in Red Hat Enterprise Linux 6.4 (RHEL 6.4) Step-by-Step Tutorial

732 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question