Thread: Formula For Circle..

  1. #1
    Registered User
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    Jun 2003

    Formula For Circle..

    Hi all,
    anyone haf formula for circle... not the pi*r*r one....
    Is the formula to get every points on the circumferece of the circle...
    Hope someone can help me....
    Thanks in advance,
    xiao guang

  2. #2
    C++ Developer XSquared's Avatar
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    Jun 2002
    Ontario, Canada
    x^2 + y^2 = r^2
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  3. #3
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    Apr 2002
    Well it all depends on what you are going to use the points for. Are you planning on drawing them to the screen? If so you can use some circle drawing algorithms here:

    If you just want floating-point numbers you could use a very naive and slow brute force method with cosine and sine..

    const float PRECISION = 0.001f;
    const float RADIUS = 150.f;
    float x, y;
    for( float i = 0.f; i < 2*PI; i += PRECISION )
      x = cosf( i ) * RADIUS;
      y = sinf( i ) * RADIUS;
      // Do something with this point...


    I should've read your question more carefully, I assumed you wanted to know how to calculate points on a circle. I didn't even see where you had type "formula". Oh well maybe someone will find this of use.
    Last edited by MrWizard; 11-17-2003 at 07:09 AM.
    "...the results are undefined, and we all know what "undefined" means: it means it works during development, it works during testing, and it blows up in your most important customers' faces." --Scott Meyers

  4. #4
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    Jun 2003
    may i noe wat precision u refer to..??

  5. #5
    ATH0 quzah's Avatar
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    Oct 2001
    Originally posted by xiao guang
    may i noe wat precision u refer to..??
    const float PRECISION = 0.001f;

    As per the posted code.

    Hope is the first step on the road to disappointment.

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