How do the Einstein@home sky-ball rotate ?

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Anonymous
18 Aug 2006 23:54:30 UTC
Topic 13417
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    From the code:

    GLfloat wobble_amp = 37.0;       // wobble amplitude, in degrees
GLfloat wobble_period = 17.0;    // wobble up/down period, in minutes
    


    vp_theta = 90.0 - viewpt_elev + wobble_amp*sin(PI2*t/(wobble_period*60.0));

    In words: the viewpoint is wobbled up and down by +- 37 degrees, with a 17-minute period. This is of course in addition to the regular rotation.

    Cheers,
    Bruce

    Bruce Allen
    Bruce Allen
    Joined: 15 Oct 04
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    How do the Einstein@home sky-ball rotate ?

    10 Sep 2006 8:15:47 UTC
    Message 3007
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      Quote:

      from what Bruce posted i see that code is written in c and using OpenGL
      i just did not expect that you would be calculating SINuses

      you could simply precalculate the values of sinuses and pick up precalculated values from the table.

      Actually the screensaver code is C++. Profiling the code shows that the sin() and cos() calls in this routine do not use significant CPU. So there's no point is using a lookup table.

      Cheers,
      Bruce

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