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Thread: Calc Perpendicular (sp?) Vector

  1. Feb 6th, 2005, 03:36 PM #1
    Halsafar
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    Calc Perpendicular (sp?) Vector

    How do I calculate a vector perpendicular to a vector?

    It is for some easy camera positioning -- creating a 2d game, need the camera to go out perpendicular from the player to a certain distance and stay there.
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  2. Feb 6th, 2005, 03:41 PM #2
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    Re: Calc Perpendicular (sp?) Vector

    A vector can have an undefined amount of perpendiculares. You have to have a "surface" to find a perpendiculare. IE. Two vectors forming a plane.



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  3. Feb 6th, 2005, 04:11 PM #3
    Halsafar
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    Re: Calc Perpendicular (sp?) Vector

    Well if you are willing to aid a bit.
    Remember mario? assume it was a 3D game and the screen scrolling was actually the camera moving. I need to know how to position my camera like that.

    The player moves in the x,y plane -- I need the camera to stay at a certain z distance. Normally this would be easy, but now and then I allow the player to move in all 3 dimensions -- when that movement stops I need to once again calculate the perpendicular of the player position and move the camera accordingly.


    Edit: heh, Well I guess this belongs in a different section now.
    Last edited by Halsafar; Feb 6th, 2005 at 04:20 PM.
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  4. Feb 6th, 2005, 06:23 PM #4
    kedaman
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    Re: Calc Perpendicular (sp?) Vector

    A vector perpendicular to a plane given by two vectors is its cross product. If you only have one vector given then any other vector will do.. of course i'm not sure what you meant here, since i haven't played mario, cept those good old snes ones
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  6. Feb 7th, 2005, 04:54 AM #5
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    Re: Calc Perpendicular (sp?) Vector

    Hmm....
    i'm guessing you have a point in the X-Y plane (X, Y, 0), and want to position the camera in another X-Y plane, but raised a certain Z distance....

    this would just be at (X, Y, Zdistance) then....

    maybe i don't undertand...
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  7. Feb 7th, 2005, 07:58 AM #6
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    Re: Calc Perpendicular (sp?) Vector

    I am guess he want a Tomb Raider follow head camera. That camera is using Quaternions, and I can't see why he needs the perpendicular for that.


    A good tutorial that is independent on what API you are using is this one. Happy reading...

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  8. Feb 7th, 2005, 01:25 PM #7
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    Re: Calc Perpendicular (sp?) Vector

    In 2D, the negative reciprocal of the slope will do.

    Y = m X + b

    The line with slope m1 is perpendicular to the line with slope m2
    m2 = -1/m1

    In multi-dimensions (and 2D), the dot product of the two vectors will be zero if the vectors are perpendicular.
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  9. Feb 8th, 2005, 01:01 AM #8
    Halsafar
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    Re: Calc Perpendicular (sp?) Vector

    My camera is using Quaternions.
    I enjoy all your comment I believe from thus I can solve it.


    Edit: Tomb Raider was a terrible game -- of its genre - which I love, it was probably the worst. Its camera was most annoying.
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  11. Feb 8th, 2005, 09:58 AM #9
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    Re: Calc Perpendicular (sp?) Vector

    Quote Originally Posted by Halsafar
    My camera is using Quaternions.
    I enjoy all your comment I believe from thus I can solve it.


    Edit: Tomb Raider was a terrible game -- of its genre - which I love, it was probably the worst. Its camera was most annoying.
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  12. Feb 8th, 2005, 11:49 AM #10
    Halsafar
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    Re: Calc Perpendicular (sp?) Vector

    I had Tifa and FF7
    or
    Celina from SO2 heh

    and of course my SNES which I made lots of non-literal love to.
    "From what was there, and was meant to be, but not of that was faded away." - - Steve Damm

    "The polar opposite of nothingness is existance. When existance calls apon nothingness it shall return to nothingness." - - Steve Damm

    "When you do things right, people won't be sure if you did anything at all." - - God from Futurama
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