Principles of operation gCAD3D

Objectcodes are stored as asciitext not binary (like HTML or XML).
  You can create / modify modelfiles (.gcad) with any editor.

Processing is done sequential by a interpreter.

Curves and surfaces (ellipses, Ruled and Revolved Surfaces) are 
  not converted into Splines/NURBS, they are stored / exported
  in their orignal form.

Programlanguage:  : C
Grafic:             OpenGL with GLU
GUI:                GTK


Modules:
  CommandInterpreter (CI):
    translate sourceobjects (Ascii-text) into binary objects.
  DataBase           (DB):
    intermediate save binary objects.
  DisplayList        (DL):
    Link to OpenGL and statusinfo for all visualisized binary objects
  Displayfunctiones  (GL)
    OpenGL-functiones

Importmodules:
  All imported objects get translated directly into gcad-sourceobjects.






Grafikprograms with interpreters:
APT
Varkon
OpenSCAD
geogebra



===================================================================
APT
===============================================================================
http://de.wikipedia.org/wiki/Automatically_Programmed_Tools



  APT-Programm    (Ascii)
NC-Prozessor      (APT,MiniAPT,APL-APT,Compact,Elan,Fapt,Exapt ..)
  CLDATA-File     (binär)
Postprocessor
  NC-Programm     (Ascii)
Werkzeugmaschine

Beispiel:

P0=POINT/X0,Y0
P1=POINT/X1,Y1
L1=LINE/P0,P1 $$ Linie durch Punkte P0 und P1
GOTO/P0
GOTO/P1
RAPID $$ Eilgang ein
GODLTA/20 $$ um 20 mm in Z-Richtung abheben



===============================================================================
Varkon
===============================================================================
http://varkon.sourceforge.net/
Interaktives GUI.
Source (Generic Model) .mbs-files.
Precompiled Objects (Bytecode, still parametric) .mbo-files.
Binary modelcode .res-files

Beispiel:

GLOBAL MODULE rhombe_param ();
    constant VECTOR o = vec(0,0,0);
    constant VECTOR a = vec(0,1,0);
    constant VECTOR b = vec(1,0,0);
BEGINMODULE
    b_plane(#1, o, o+a, o+a+b, o+b);
ENDMODULE



===============================================================================
OpenSCAD
===============================================================================
http://www.openscad.org/
3D-compiler, creating solid 3D CAD objects.
Kein interaktives GUI.


Beispiel:

circle(r = 10);
rotate([90,0,0]) polygon( points=[[0,0],[2,1],[1,2],[1,3],[3,4],[0,5]] );



===============================================================================
geogebra
===============================================================================
http://www.geogebra.org/
Erstellung und Berechnung mathematischer Figuren.
2D, interaktives GUI. XML-Ausgabe.