Скачать Turtle 1.0 - Turtle Graphics in any SVGA BGI Mode

14.12.1992
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TURTLE version 1.1e Unit that allows turtle graphics in any BGI mode

  Copyright (c) P.Pollet 1991,1992
  Portions of SVGA handling copyright (c) 1992 J.P.Hardgrave
  Procedures and Functions names (c) Borland Int'l  1987-1992

This unit is hereby donated to the public domain provided:
    - the copyright notices are not removed nor modidied.
    - proper citation of authors is made upon usage in other packages
    - the archive contents is not modified

Please report all problems, bugs, suggested modifications to the author

Dr Patrick L.Pollet     ppollet@cismibm.univ-lyon1.fr
Institut National des Sciences AppliquВes
Centre informatique du 1er Cycle    Bat 110
20 avenue A.Einstein
69621  Villeurbanne Cedex France

Archive contents:

TURTLE   DOC      This file
DRAGRECT PAS      2411 14.12.92   10:17Demo program Clover dragon
FOREST   PAS      3737 14.12.92   10:44Demo program draw a nice forest
NICETREE PAS      3124 14.12.92   10:45Demo program Draw a nice tree
SVGA     INI      3192 14.12.92   10:31Include file to use SVGA.BGI
SVGAREG  DOC      3122 14.12.92   10:27Registration form for SVGA.BGI
SVGA256  BGI      6335 09.09.92    9:11SVGA.BGI driver (C) J.Hardgrave
TREEREC  PAS      1539 14.12.92    9:55Demo program Regular trees
TURTLE   PAS     24153 14.12.92   10:30Source code unit Turtle
TURTLEDM PAS      4576 14.12.92   10:05Demo program Play with turtle
VONKOCH  PAS      1977 14.12.92   10:29Demo program Von Koch SnowFlake

Why did I wrote that unit ?

Do you remember that little turtle with a pen at the tail that was the main feature of the Logo language ? A toy to learn computers to kids ??? Well not so...

For my fellow teachers in C.S., turtle graphics are an exellent introduction to recursion , with quite attractive visual effects. Drawing "dragon curves " (Von Koch snowflake, Peano's curves...) is so natural with this little friendly animal....

Another application is in the representation of 2D shapes by relative motions of the turtle ; that by a couple ( distance, angle ) from a previous point. This makes the manipulation of the shape much easier than with the standard cartesian coordinates representation. A translation just requires changing the starting point of the drawing ; rotations can be obtained by changing the turtle heading and zooming is done by changing the pixel/distance ratio for the turtle motions. Nearly no trigonometric calculations are required to transform a shape ...

Borland had introduced turtle graphics with TurboPascal 3. In the subsequent versions, a compatibilt unit, TURBO3 was provided but, even with version 6, it can only do turtle graphics in the old CGA graphic modes !!! Quite desappointing at the era of SVGA boards....

This unit , TURTLE.PAS make possible the use of a turtle with any graphic mode supported by the Graph unit. whether it is a standard graphic mode (EGAVGA,HERC,IBM8570..) or a user written BGI driver such at the remarkable shareware SVGA drivers written by .......

To allow a nearly direct recompilation of previous programs, the entries points are identical , in names and parameters with the Turbo3 unit interface.

technical notes:

    This unit has been tested with all  BGI drivers supplied
by Borland Int'l in Turbopascal packages version 5.5  and 6.

    User installed BGI drivers were tested only with SVGA.BGI
driver of J.P.Hardgrave.

    The source code is self-documented.