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The Datafile PD-CD 5
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DATAFILE_PDCD5.iso
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!Pottery
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1993-11-26
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!Pottery
********
Version 2.10 3rd September 1993
By Richard Seago
With routines from Rob Miller of BBC Acorn User (May 1990)
Pottery is a program which allows you to create solids of rotation from a
simple path defined by a few mouse clicks.
Pottery has two windows. One in which you design the outline of your shape,
and one in which you see what it looks like. The black one is the one which
displays the shape. Because the program trys to use 256 colours it needs one
of these modes to show the solid properly but it will try its best with the
ColourTrans module in other modes and for printing (which produces best
results with grey on a monochrome printer).
The left hand side of the edit window contains the functions. The long,
vertical, black line is the axis about which the solids are formed. The
functions are (from top to bottom):
i) Line - this draws a line on the edit window and a three dimensional
shape in the draw window.
ii) Move - this draws a faint line in the edit window and allows gaps in
the picture in the draw window.
iii) Grey - this word changes telling you which hue the currently selected
colours will produce on screen.
iv) Blue - this selects/deselects the blue component of the shape's
colour.
v) Red - this selects/deselects the red component of the shape's colour.
vi) Green - this selects/deselects the green component of the shape's
colour.
The shape is entered as a continuous path. The path can be started at the
top or bottom of the edit window, although the direction should be kept
consistent through out because of the way that the shape is drawn. If the
shape is drawn top down, in order to represent it correctly on screen the
entire shape must be redrawn. This can slow things down for complex shapes
so you may wish to turn off continous update. This option is in the 'Update'
sub-menu which can be called up from the display window. There are no such
problems if you draw bottom up, because the shapes are drawn in order that
you might look at them from slightly above.
Each segment has a seperate colour characteristic which is set before it is
drawn. However, this can be changed by clicking with Menu on the point
before the segment you wish to change the colour of. The selected segment
will turn orange, the colour may then be changed via the Colour sub-menu.
The last point in the path may be deleted or the entire path cleared. You
may also drag any point with Adjust to change its position. If the program
gets behind with updating the sprite, or you have turned off the continuous
update option, you will have to select 'Update' from the draw menu to see
the shape properly - this may take a few moments.
The sprite is also completely redrawn when you click Select on the iconbar
icon. Adjust will open the edit window only. The windows can be closed
separately, and no data will be lost. Mostly, however, the program is self
explanatory and should display helpful messages if something's wrong.
The program can load and save in its own file format which can be treated as
if it had just been created. The program can also save the 3D shape as a
sprite file. The sprite will be saved as a sprite in whatever mode is
currently in use.
A second method of inputting shapes into !Pottery is from a shape
description file in the form of a text file. This allows greater accuracy
and can be editted as if it were an ordinary !Pottery file. However it
cannot be saved back as a text file. The file does not have to be
filetyped as text as long as the format of the file is correct. The text
file should be of the format:
Shape - This is a literal keyword and is case sensitive,
it allows !Pottery to determine what sort of file
has been loaded. It should always be the first
word of the file and the file should be continued
on the next line. Comments may be added but not on
the first line of file. Any line whose first word
is not one of those below, will be treated as a
comment.
gcol <colour> - This keyword allows you to set the colour of the
path segments upto the next gcol. The <colour>
parameter is a word from the following list:
grey or white
magenta
cyan
yellow
green
blue
red
clear or black (has the same effect as a
move)
move xxx,yyy - This keyword moves the drawing cursor to the point
xxx,yyy. It is up to the user to ensure that the
points lie within the viewing area, as no error is
produced otherwise.
draw xxx,yyy - This keyword draws from the previous cursor to the
point xxx,yyy. The same constraints as above
apply.
All these commands (and parameters) are case sensitive - if they are not
correct they will be ignored as comments.
The print option uses RISC OS printer drivers. The printing of the shapes is
not done from the sprite but from the outline so the best image possible
should be produced on all printers.
If you should change modes within the desktop, !Pottery will take a few
moments to readjust, making sure that the sprite appears the same size and
in the best colours possible. It will also warn you on entering (or starting
up in) a non-256 colour mode that it cannot do its best when drawing the
shape in that mode.
The program is slightly naughty in that it uses RMA space to hold the
sprite. This has never caused me any problems, and I don't see why it
should.
I can only say that the best way to get to grips with !Pottery is to try it.
The sprites produced can be very effective.