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3D.doc
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1986-11-20
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--------------------------------------------------------
Documentation for 3DGrapher, copyright 1987 Randy Finch.
--------------------------------------------------------
This program consumes mucho memory. Therefore if you only have
512K, do not load Workbench and resize CLI window very small. The
program makes AmigaDOS calls, thus it must be loaded from CLI.
Make sure AmigaBASIC, 3DGrapher, dos.bmap, and graphics.bmap are
on the same disk. Insert in df1:. If you have no df1:, then buy
one quickly, OR make sure you change curdir$ near the beginning of
the program to df0:, or dh0: (lucky you!), or whatever. First
change the current directory to df1: or whatever you've chosen,
run AmigaBASIC, enter CLEAR,75000 in immediate mode, and then load
3D (it is in ASCII format). If you have a 512K machine,
resize the output window to a small size, close the list window
and run the program. The program is menu driven; the text below
explains these menus.
There are four main menu items: SET, COLOR, FILE, and FUNCTION.
------------------------------------------------------------------
Under SET are the following:
Origin:
Just click the LMB with the pointer over the point on the
screen where the axes origin is to be. If the origin is
offscreen, click in the extreme upper left hand corner of the
screen and a requester will allow you to enter the point. This
origin point is actually the point where the line from the origin
to your eyeball intersects the projection plane. (See Projection
Plane below).
Rotation:
This allows you to set the rotation angles from the default
axes orientation. The default is X positive to the right, Y
positive upward, and Z positive perpendicular to the screen
towards YOU! A positive rotation about an axis is accomplished by
holding the positive half of the axis and rotating clockwise. (I
know this is opposite to what some of you are used to, but I like
to be different.)
Scale:
This sets the number of screen pixels that represent one
unit along the axes. The larger this number, the more magnified
the graph will be.
View Distance:
This is the distance in units the viewer is from the
projection plane. (Don't go holding a ruler from your eyeball to
the screen.)
Projection Plane:
This is the distance along the Z axis (default orientation)
that the projection plane is from the axes origin. It can be
positive or negative. The CRT screen is always the projection
plane, so this determines whether the origin is in front of or
behind the screen and how far away it is.
Line Spacing:
The program draws a wire frame of the graph. This menu item
allows the user to set the spacing of the wires in the X and Y
directions (by units, not pixels).
Plot Precision:
This sets how far apart each plotted point, along individual
wires, is in units. 3DGrapher tries to prevent a point farther
away from the viewer from overwriting a point closer to the
viewer. This will be more effective if the plot precision is high
(small value for spacing). Also, the plot will look smoother with
a high precision. Typically, while experimenting with a new
graph, it is good to plot with a wide line spacing and a low
precision until the graph is oriented the way you want. Then set
the line spacing to a smaller value and increase precision for the
final plot since this will take longer.
Plot Span:
The range for the plot along the X and Y axes.
Axes Span:
The range for plotting the axes along the X, Y, and Z axes.
Also, the precision of the axes plot can be set here. Unlike the
plot of the graph, which connects points with a line, the axes is
drawn as a series of dots. The precision sets how far apart these
dots are in units.
Crosshatch On:
This will cause the program to plot the graph as a
crosshatched wireframe, drawing wires along the X and Y axes.
Crosshatch Off:
This will cause the program to draw along only one axis. You
choose which axis it will be. This setting is recommended if the
line spacing is very small because there is no need to crosshatch
if the graph is nearly solid anyway.
Axes On:
Plot the axes.
Axes Off:
Do NOT plot the axes.
------------------------------------------------------------------
Under COLOR are the following:
Background:
This selection brings up some RGB sliders that allow the
screen color to be set.
Graph:
The actual graph is plotted using 16 colors. The default
colors range from a deep blue to white with shades of blue in
between. The deep blue represents points far from the viewer,
while white represents points near the viewer. This requester
allows the user to change the far and near colors; the program
will create an even transition for the 14 colors in the middle.
Axes:
Set the color of the axes.
Border:
Set the screen border color.
Text:
Set the color of any text the program puts on the screen.
----------------------------------------------------------------
Under FILE are the following:
Save Picture:
Save the screen bitmap to disk. The program will add the
extension ".3D" to the filename. You will be warned if the file
exists. This routine using AmigaDOS calls so make sure the C:
directory is available. The save takes about 90 seconds so be
patient. (NOTE: I like to use a popup IFF saver to save the
screen as an ILBM file that can be read into DPaint.) The
settings will be saved also.
Save Settings:
This will allow you to save all those settings under the menu
SET to disk. An extension of ".SET" will be added.
Get Picture:
Retrieve a bitmap from disk. You can view the directory;
only .3D files will be seen. You can also change directories from
this routine. This is a lengthy process like Save was. The
settings will also be retrieved.
Get Settings:
Retrieve settings from disk.
------------------------------------------------------------------
Under FUNCTION are the following:
Plot:
Begin plotting the graph.
Stop Plot:
Interrupt the graph plotting.
Input Equation:
There is no direct way to input the equation. When you
choose this option, the program will end and the list window will
appear with the equation definition statement at the top of the
window. Edit this equation and then copy it to the string
equation$ defined under the DEF FN statement. This string is
used for viewing the equation when the Show Equation menu item
is chosen, and is also used to make sure there is no mismatch of
picture and settings after saving and loading. Please note that
this equation is in the form Z=F(X,Y). By only defining either X
or Y in the equation and carefully selecting plot ranges and
rotation angles, a two-dimensional plot can be made.
Show Equation:
Displays the current equation (assuming you followed the
directions above).
Show Settings:
Displays all the settings that can be changed under SET on
the screen at once. No changes can be made from here.
Quit:
Stop running this program. I'm sick and tired of looking at
graphs.