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The Datafile PD-CD 3
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drawpersp
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!DrawPersp
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1995-04-26
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This is !DrawPersp, version 1.24 (28 April 1995)
Intro
=========
This is essentially a vector program, with which you can create drawfiles.
Its special feature is that its drawing tools all provide operations, that
take into account the perspective of a scene.
Perspective
============
Perspective is caused by the fact that objects appear smaller, the further
away they are. This causes vertical, and horizontal surfaces, to scale down
smaller at greater distance, and if they were continued, would tend to
disappear, or become infinitessimally small, at an infinite distance away.
Such a place we call a 'vanishing point'.
A scene in which all buildings are laid out in a true rectangular grid, will
have two vanishing points, but normally only one will be in a visible area
of a picture at a time. When they both show a distorted effect can be
achieved.
If one vanishing point is in the centre of the picture, a drawing of a scene
looking straight down a straight road can be achieved. If it is placed off
centre an effect of looking across a road in a slanting way can be made.
Use
===
The best mode for this is 21 or 28. Other modes work but some give
poorer results.
The select button is used for most operations described below, while with
one exception adjust provides you with temporary vertical and horizontal
guides, emanating from the pointer.
The program is installed on the icon bar in the usual way, by clicking on
the icon in the directory. The drawing window is opened by clicking on this,
and a white screen, with a toolbox and a small cross in the middle can be
seen. This cross represents the visible vanishing point. Other vanishing
points are sited off the screen at infinite distances away each side.
The top icon can be selected and the vanishing point can then be resited. In
general to get a drawing that looks correct you need to keep it about two
thirds of the way up the screen. Putting it higher gives the impression of
looking from on high. Putting it low gives an ant's eye view.
The next icon down is use for rubber banding. This is used as in !Draw, and
draws in the selected colour. This operation is the only one that does not
consider perspective; any line can be drawn.
The next icon down draws vertical surfaces. Dragging will only work from top
to bottom. dragging towards the visible vanishing point, draws a surface,
that would vanish at that point. Dragging away from it draws a surface that
would vanish at the other vanishing point, off of the screen. The textures
sub menu allows you to choose, unfilled, filled, brick, weather board, or
block. Spacings of these, can be altered from this sub menu too.
The next icon is for drawing horizontal surfaces. Click and drag, to see a
surface drawn, which tends to disappear the nearer it gets to a vanishing
point. There is a bug in this, and it pays to drag from bottom left to top
right if possible. By selecting one of the options in the sub menu, you can
choose unfilled, filled or paved options. The paved one does not yet, obey
correct perspective, but looks good. The field texture is not yet
implemented.
The next icon is for dragging simple lines, that go towards or away from
vanishing points. This probably won't often be useful, as all lines on a
picture are really more accurately described as surfaces.
The next icon is for dragging out objects that are not vertical or
horizontal. This action is used for drawing roofs. Unlike the other tools
this one has to be dragged once to do the non vertical non horizontal bit.
The next drag then creates the surface.
The next icon provides the user with a tool to plant fractal trees and
bushes at the place of the pointer. These trees can't be drawn above the
vanishing point which would be in the sky. They obey the rules of
perspective, becoming smaller further away, though their actual size, can
also be changed from their sub menu as well.
The palette icon is not implemented
However OLE is now working, so in a very satisfying way a click with Ctrl.
held down, loads the drawing into !Draw, if it is available. This can be
used to change colours, and delete objects etc.. For those unfamiliar with
OLE, a Save from !Draw, best achieved by pressing F3 perhaps, will save the
edited file back into !DrawPersp.
Saving
======
This can be accomplished, from the main window menu, in the
usual way. The
Drawing ======= Users should experiment, with the above tools. Artists who
understand the rules of perspective, may find it easy, and it may be of use
to teach perspective. It is limited in several ways, by simplification, and
it really needs a fast machine, as it is written in basic, and it needs to
use a high resolution mode.
Future
======
!DrawPersp should include in the future:
Full colour
More textures
More fractal options
Less bugs and more simplifications
Copyright
=========
This program is Public Domain. It may be distributed or
copied freely as long as no part of this software may is used in any other
program, whether commercial or public domain, without my prior written
consent, though any files created by this software are not bound by this
condition. This software may not be distributed for a profit, save that
required to cover packaging and media costs..
Copyright (©) is retained by the author, who may be contacted at the address
beneath. No liability can be accepted by the author for any loss or damage
arising from use or misuse of this software.
The Fractal trees are copyright of RiscUser and used with their permission.
EventShell
=========
Thanks to Paul Hobbs for his very useful !EventShell System.
This application uses the library of routines of the above name, which
provide an easy way of genereating a Wimp Program.
I recommend this system which can be obtained from APDL or other PD
Libraries.
This program has been written using the routines supplied with the EvntShell
library which is copyright Paul Hobbs. The library routines may be
distributed subject to the following conditions:
You have permission to use any part or the whole library in a project you
intend to place in the public domain, as long as I am fully credited (via
the inclusion of this file in the program documentation). If you wish to use
these routines in a program that is for sale (for however much and for
whatever reasons) or released as copyright material then my express
permission in writing must be obtained. I maintain copyright on all the
material supplied and reserve the right to amend these conditions in cases
where I deem misuse.
The library code is supplied free of charge to everyone 'as is'. There is no
guarantee that it is free from bugs and no warranty is given about its
suitability for use.
Further details about EvntShell may be obtained from the author:
Paul Hobbs Rheinpfalzstrasse 2 85049 Ingolstadt Germany
The heap manager routines used by EvntShell are copyright Risc User and are
used with permission.
-----------------------------------------------------------------------------
Any improvements or bugs, please report to :-
Robert Seago.
40 Alton Park Road
Clacton On Sea
Essex.
CO15 1ED