Math + Code

This is a discussion on Math + Code within the C++ Programming forums, part of the General Programming Boards category; Alright, I'm working in a simple graphics library, graphics.h, which can be downloaded here: http://www.uniqueness-template.com/devcpp/ I'm currently working on a ...

  1. #1
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    Question Math + Code

    Alright, I'm working in a simple graphics library, graphics.h, which can be downloaded here:
    http://www.uniqueness-template.com/devcpp/

    I'm currently working on a simple game which required me to be able to have a center point, and rotational value (0-360) and then be able to draw a square that has sides with a length of exactly '5' around the point at the correct rotational value... how would I accomplish this? (I need the formula)

    (Separating the points is preferable... I'd like to know where each corner is)

    Thanks in advance...

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    What are you using to write this game, openGL, openAL, directx, something else? There isn't a precise "formula" that fits every application, but you need to figure out what angle you are rotated from according to the Z and X axis (looking from the top on a 3D plot). Then rotate that much about the Y axis. For moving the box with the rotation just make the rotational value effect the box also.

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    No no no... I'm not using Open GL or anything like that, open the graphics library in the download and take a look at it, you'll understand it in about 5 seconds... it's really really basic. I'm actually going to need to draw the square line by line, so truely I just need the points based off of the rotation... it's a mathematical formula I want...

    Given:
    Length between points (5)
    Center of the square
    Desired rotational value (0-360)

    Expected result:
    Four points that when connected make a square at the proper rotation.

    Thus a rotation of '0' would yeild
    _ _
    |_|

    (The top wouldn't extend over the sides, but you get the idea..

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    Its hard... But im here swgh's Avatar
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    graphics.h is an old borland pre-standard header, I dont think many modern compilers support it.
    I'm just trying to be a better person - My Name Is Earl

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    Yes it works

    It works... I've used it... with Dev-C++ (compiler)

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    Dr Dipshi++ mike_g's Avatar
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    Thumbs up

    In pseudocode you could do it something like:
    Code:
    rotation = 0;
    diagonal_length = sqrt((width * width)+(height * height));
    radius = diagonal_length / 2;
    x[4]
    y[4]
    
    for(int i=0; i<4; i++)
    {
        x[i] = center_x + (cos(rotation)*radius); 
        y[i] = center_y + (sin(rotation)*radius); 
        rotation+=90;
        rotation%=360;
    }
    Then just draw lines between the points. You would also have to convert degrees to radians. But it should give you an idea of how it can be done.

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