Help on sun settings in RBR

Discussion in 'Bob's Track Builder' started by eno72, Apr 21, 2009.

  1. eno72

    eno72

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    It seems that moving the sun in btb does not effect the sun position in RBR. Actually, the settings.ini contains three lines with "sun direction" and 3 numbers per line. These numbers are always the same when exporting, and I cannot figure out how they are related to the coordinates of the sun, maybe I missed a thread about it...
     
  2. jharro

    jharro

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    2 of those lines have ";" at start which means they are commented, so they are ignored.

    the 3 values are the X, Z and Y of the the sun direction, not position, in example :
    zenith(above): sunDirection = 0, -1, 0
    right(east) 45degree: sunDirection = -0.707107, -0.707107,
    left(west) 45degree: sunDirection = 0.707107, -0.707107, 0.0
    back(south) 45degree: sunDirection = 0, -0.707107, 0.707107
    etc.

    you can use a sun position calculator to obtain the angles

    if:
    azimuth = 176.05
    altitude = 48.42
    then:

    x = sin(176.05) * sin(48.42) = 0.0688859 * 0.7480298 = 0.0515287
    z = cos(176.05) * sin(48.42) = -0.99762455 * 0.7480298 = -0.74625289
    y = cos(48.42) = 0.66367

    sunDirection = 0.0515287, -0.74625289, 0.66367

    if you don't want to bother with the math you can always draw a line with length 1 unit in max or any other 3d editor, rotate the line by x for altitude and z for azimuth. if the line's start is at origin(0,0,0) then the coordinates for the other end are exactly the values you need for sun direction.
     

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  3. eno72

    eno72

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    thanks a lot, very kind of you. Really exhaustive, should be mentioned in the help file of btb!
     
  4. jharro

    jharro

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    not really, no, you can google math.
    :)