planet
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## planet

planet — Simulates a planet orbiting in a binary star system.

## Description

planet simulates a planet orbiting in a binary star system. The outputs are the x, y and z coordinates of the orbiting planet. It is possible for the planet to achieve escape velocity by a close encounter with a star. This makes this system somewhat unstable.

## Syntax

    ax, ay, az planet kmass1, kmass2, ksep, ix, iy, iz, ivx, ivy, ivz, idelta \
          [, ifriction] [, iskip]

## Initialization

ix, iy, iz -- the initial x, y and z coordinates of the planet

ivx, ivy, ivz -- the initial velocity vector components for the planet.

idelta -- the step size used to approximate the differential equation.

ifriction (optional, default=0) -- a value for friction, which can be used to keep the system from blowing up

iskip (optional, default=0) -- if non zero skip the initialisation of the filter. (New in Csound version 4.23f13 and 5.0)

## Performance

ax, ay, az -- the output x, y, and z coodinates of the planet

kmass1 -- the mass of the first star

kmass2 -- the mass of the second star

## Examples

Here is an example of the planet opcode. It uses the file planet.csd.

Example 697. Example of the planet opcode.

See the sections Real-time Audio and Command Line Flags for more information on using command line flags.

    <CsoundSynthesizer>
    <CsOptions>
    ; Select audio/midi flags here according to platform
    ; Audio out   Audio in    No messages
    -odac           -iadc     -d     ;;;RT audio I/O
    ; For Non-realtime ouput leave only the line below:
    ; -o planet.wav -W ;;; for file output any platform
    </CsOptions>
    <CsInstruments>

    ; Initialize the global variables.
    sr = 44100
    kr = 44100
    ksmps = 1
    nchnls = 2

    ; Instrument #1 - a planet oribiting in 3D space.
    instr 1
      ; Create a basic tone.
      kamp init 5000
      kcps init 440
      ifn = 1
      asnd oscil kamp, kcps, ifn

      ; Figure out its X, Y, Z coordinates.
      km1 init 0.5
      km2 init 0.35
      ksep init 2.2
      ix = 0
      iy = 0.1
      iz = 0
      ivx = 0.5
      ivy = 0
      ivz = 0
      ih = 0.0003
      ifric = -0.1
      ax1, ay1, az1 planet km1, km2, ksep, ix, iy, iz, \
                           ivx, ivy, ivz, ih, ifric

      ; Place the basic tone within 3D space.
      kx downsamp ax1
      ky downsamp ay1
      kz downsamp az1
      idist = 1
      ift = 0
      imode = 1
      imdel = 1.018853416
      iovr = 2
      aw2, ax2, ay2, az2 spat3d asnd, kx, ky, kz, idist, \
                                ift, imode, imdel, iovr

      ; Convert the 3D sound to stereo.
      aleft = aw2 + ay2
      aright = aw2 - ay2

      outs aleft, aright
    endin

    </CsInstruments>
    <CsScore>

    ; Table #1 a sine wave.
    f 1 0 16384 10 1

    ; Play Instrument #1 for 10 seconds.
    i 1 0 10
    e

    </CsScore>
    </CsoundSynthesizer>

## See Also

More information on this opcode: http://www.csoundjournal.com/issue9/FlutesInOrbit.html , written by Brian Redfern.

## Credits

Author: Hans Mikelson
December 1998

New in Csound version 3.50

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