Help on sun settings in RBR

eno72

100RPM
Mar 16, 2009
121
10
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...
 
J

jharro

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 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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eno72

100RPM
Mar 16, 2009
121
10
thanks a lot, very kind of you. Really exhaustive, should be mentioned in the help file of btb!