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- <MAINMENU>
- MAIN MENU
- Move the highlight with the arrow keys
- then make a selection with the ENTER key.
-
- <EDITMASS>
- MASS
- Enter the mass of the planet
- in Kilograms (Kg). The number
- given must be greater than or
- equal to zero.
-
- <EDITDENS>
- DENSITY
- Enter the density of the planet in
- Kilograms per cubic Meter (Kg/M^3).
- The value given must be greater than
- zero. The density of water is 1000
- (1E03) Kg/M^3.
-
- <EDITX >
- X POSITION
- Enter the X position of the
- planet in Meters.
-
- <EDITY >
- Y POSITION
- Enter the Y position of the
- planet in Meters.
-
- <EDITVX >
- X VELOCITY
- Enter the X component of the
- velocity in Meters per Second (M/s).
-
- <EDITVY >
- Y VELOCITY
- Enter the Y component of the
- velocity in Meters per Second (M/s).
-
- <EDITTRAC>
- ORBITS
- This field enables plotting of the
- orbit dots that mark the path of
- the planet as it moves. The dots
- will only display if the Show Orbits
- setting under the Misc menu is ON.
- Valid values for this field are Y
- and N.
-
- <EDITSTAT>
- STATIONARY
- This locks the planet firmly in
- place. New position values are
- not calculated for stationary
- planets. This is an imaginary
- condition and should not be used
- if you are modeling an actual
- system.
-
- <CONSTZOO>
- ZOOM POWER
- Changing the zoom power allows you to
- "Zoom-in" and "Zoom-out" to view orbit-
- ing bodies at varying magnifications.
- To zoom-out and see the whole system,
- use small values. To zoom-in and make
- objects appear very big, use larger
- values.
-
- This value is also changeable from
- the running simulation by using the
- PgUp, PgDn, and Home keys.
-
- <CONSTXCE>
- X CENTER
- This is effectively a panning value. You
- enter where in space you would like the
- center of the screen (X direction) to show.
-
- This value is also changeable from the
- running simulation by using the arrow
- keys in conjunction with PgUp and PgDn.
-
- <CONSTYCE>
- Y CENTER
- This is effectively a panning value. You
- enter where in space you would like the
- center of the screen (Y direction) to show.
-
- This value is also changeable from the
- running simulation by using the arrow
- keys in conjunction with PgUp and PgDn.
-
- <CONSTTIM>
- TIME INTERVAL
- Time Interval is how long a force acts on a
- planet in seconds, or in other words, the
- elapsed time between new velocity and position
- calculations. The planet motions are simulated
- not by curves, but by many very short lines.
- The time interval relates to the length of those
- lines. Since in reality they are 0 in length,
- the smaller this number the better. You may
- lower this number for accuracy, or increase it
- for speed. If the planets are not moving more
- than a few pixels per plot, depending on how
- sharply curved the planet path is, the accuracy
- you are getting is probably fine. This value
- can be automatically determined with the Dynamic
- Time Interval function ('D' on the simulation
- screen).
-
- <CONSTG >
- GRAVITATIONAL CONSTANT
- The gravitational constant is the strength
- of the gravitational field. You should not
- need to change this value, but it is included
- for versatility. Changing it will affect the
- units used for mass, density, distance, and
- velocity. The value of +6.67E-11 is the
- actual value found in reality.
-
- <CONSTCPP>
- CALCULATIONS PER PLOT
- Actually a bit of a misnomer, this really
- relates to Plots per Calculation. It only
- affects the frequency of plotting positions
- on the screen, not how the calculations
- are done, or the paths planets will take.
- You may want to change this when you are
- watching the Status Line, or if you have
- very slow display hardware.
-
- <CENTRAL >
- CENTRAL PLANET TRACKING
- You can watch the simulation from the perspective
- of any one of the defined planets. This will plot
- the specified planet in the center of the screen
- and the other planets will move in relation to it.
- This does not affect how the calculations for move-
- ment are performed, only how the planets are disp-
- layed. Using this, you can follow the orbit of one
- system which is part of a larger system. For
- instance, you can watch the earth-moon system up
- close while it revolves around the sun without
- having to do zoom/pan/zoom/pan/etc. An entry
- of 0 will turn off this feature.
-
- This function is also available from the running
- simulation by pressing first the 'C' key, and then
- the key for the planet you want to track
- (1-9, ! @ # $ % ^ &).
-
- <STATUS >
- STATUS LINE
- Displays the current status of a planet. Values
- displayed include: Planet number, Mass, Position,
- and Velocity. If the planet collides with another,
- the status switches to the live planet. A value
- of 0 turns this function off.
-
- This function is also available from the running
- simulation by pressing first the 'S' key, and then
- the key for the planet you want the status displayed
- for (1-9, ! @ # $ % ^ &).
-
- <SAVE >
- SAVE FILE
- Enter the full drive, path, and name of the
- file you want to save to. If you omit the
- path, the current directory is assumed.
- If you omit the extension, .GRV is appended.
-
- <RESTORE >
- RESTORE FILE
- Enter the full drive, path, and name of the
- file you want to read from. If you omit
- the path, the current directory is assumed.
- If you omit the extension, .GRV is appended.
-
- <YESNO >
- Answer with the Y or N key.
-
- <VIDEO >
- VIDEO DISPLAY TYPE
- If for some reason your graphics hardware
- is incorrectly detected, you may select
- the proper type to use here. Also, if
- your monitor supports other resolutions
- than the one detected, you can specify
- the one to use. Choosing a lower reso-
- lution display may speed up the simu-
- lation.
-
- This selection can also be specified on
- the command-line when you start the prog-
- ram. Use the option /? for a list of
- choices.
-
- <END>
-
-