The World of Computer Software/World_Of_Computer_Software-02-387-Vol-3of3.iso/p/povcad10.zip/POVCAD.DOC

Text File | 1993-02-27 | 20KB | 525 lines

                             POVCAD 1.0 by
                            Alfonso Hermida
                     Pi Square BBS [phone]
                                2/26/93

NOTE: POVCAD is written in Visual Basic 2.0 for Windows (Microsoft Corp).
      To run it you'll need the runtime module VBRUN200.DLL.

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Copyright (c) 1993 by Alfonso Hermida.
All rights reserved.  The program POVCAD.EXE is distributed "As is".
The author assumes no reponsibility for damages resulting from the use of
this program.  The program has been tested but no software is "bug-free"
so...use at your own risk!
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Distribution:
Feel free to distribute POVCAD.EXE and it's companion file POVCAD.DOC for
non comercial purposes.  Distributors may charge up to $5 for this program.
If you wish to distribute this program with a comercial software please
contact the author at the BBS number given above or by mail:
       Alfonso Hermida, 9346 Kings Grant Rd, Laurel, MD 20723.

This program is distibuted as Shareware.  You may use this program for
a period of 30 days at which you must either register this software or
stop using it.  Registration entitles you to support thru the BBS.

Registration cost is only $15 and helps continuing work to improve this
software.  To register send your check or money order to the above address
with your name, address, phone number and a password(for BBS access).  Check
at the end of this document for registration form.

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What's POVCAD?

POVCAD is a small solid object modeling tool to create scene files for
raytracers.  It's based primarily on the POV(Persistence of Vision)
raytracer written by the Persistence of Vision Group.  POV is a copyrighted
freeware raytracer.  If you would like to get in contact with them,
contact Compuserve [phone], Comart forum Raytracing section 16, or
call YCCMR BBS [phone], which is a raytracer specific BBS.

With POVCAD you're able to create visually the scene file and have a
pretty good idea (geometry-wise) of how the objects are positioned in
3D space.  There is no support for textures and color visualization since
POVCAD is a wire frame-based program.  Nor, you'll see the results of
any constructive solid geometry operation (boolean operation..for short).


POVCAD supports the following objects:
* planes
* cylinder
* cone
* sphere
* ellipsoid
* torus
* box
* height_field
* Raw data files (loading)
* Sweep (solid of revolution)
* light_source

and operations such as union, difference,intersection and composite
objects.  Textures can be selected from a list without need of typing.
The scene view can be changed between isometric,YX,YZ and ZX.
A session list shows the steps you took to create any image and you may
select any of the objects from the list by clicking on it.

An interesting feature is the ability to create or read data files
with path information for animation software.  You can create linear
interpolated data, circular motion, parabolic, helix or just freehand
mode, where you sketch the path with the mouse.  POVCAD does not do
animation but it plots the path files so you can see how things look
on the screen.  The data can be transformed like any object in POVCAD.

In the File menu, there is an option to save the session file and to
Export to POV (that is to create the POV session file).


AN IMPORTANT NOTE:  All rotations and translations are absolute(measured
from the origin).  Therefore, if an object has been translated to (1,1,1)
and you change the x to 1.5, it will be (1.5,1,1) and not (2.5,1,1).

My best suggestion is that you play with it for a while to get a better
understanding of the program.


Creating an Object

To create an object is easy.  Here are the steps:

1) Click on the Object menu and click again on the object you would
   like to create.  All objects start at the origin, except the sphere
   which asks for the center coordinates.

2) To rotate/translate or scale the object, click on Xform and select
   the appropiate transformations.  The way this program was developed,
   rotations are ALWAYS applied first THEN the translations.   Keep that
   in mind.

3) If you need to edit/delete an object, click on Session and click on the
   object to be modified.  On the bottom right part, the current object
   is shown, with it's texture.  If the object is already there,  you can
   operate on it without having to click on Session.

NOTE:The LAST object created is ALWAYS the current object.  If you wish
     to tranform it, just go directly to Xform or Texture (if you want
     to put a texture to it).

   To delete an object, either select it (thru the Session menu) or just
   go to Edit if it's the last object drawn and click on Del.


NOTE: The format of RAW data files is:
  x1 y1 z1 x2 y2 z2 x3 y3 z3
  x4 y4 z4 x5 y5 z5 .......
  ...... ect ..............

where each line represents a triangle.  Usually I use Steve Anger's
RAW2POV program to create objects with RAW data files.  RAW2POV will
optimize A LOT the image, while POVCAD will just convert the data to
triangles and that's it!

Creating Solids of Revolution (Sweep command)

1) Click on the PointOff button (to enable point creation)
2) Select a View different than Iso (i.e. YX,ZX or YZ)
3) Click on the window and draw a contour (up to 25 points)
4) Select the Sweep command from the Objects menu
5) give a filename.ext (the data will be saved in RAW format)
6) indicate sweep angle and number of segments

* If you wish to erase the points and start all over use the Del Points
  command in the Edit menu.
* SnapOn forces the points to fall in the intersections of the grid
  lines, while GridOff let's you select any place on the screen.



Creating Constructive Solid Geometry

Let's use an example to explain this topic:
We'll assume we want to create a cylinder with a hole in the middle.
Since the operation is a difference:

1) click on CSG and then select "difference".
2) create the cylinder and position it.
3) create a sphere (the hole) and position it.
4) Click on CSG and then "Close".

Close is the command to tell the program that the current CSG operation
has ended.  The Session list would look like this:

DIFFR
CYL ........
SPH ........
ENDF

Where:
DIFFR   = difference operation
CYL ... = cylinder definition and transformations
SPH ... = sphere definition and transformations
ENDF    = tells the program that this is where the difference operation
          ends

Now let's assume that you want to create a union of 2 cylinders each
one with a hole in it:  This is how the Session list would look like:

                      comments:
UNION                  1) union operation starts here
DIFFR                  2) difference operation starts here
CYL ....               3) cylinder #1
SPH ....               4) sphere #1
END                    5) clicked on CSG then on Close
DIFFR                  6) Start another difference
CYL ....               7) cylinder #2
SPH ....               8) sphere #2
END                    9) clicked on CSG then Close
ENDF                   10)clicked on CSG then Close
                         (click on TEXTURE to add one to the object)

As you can see, the software uses END and ENDF to distinguish between
intermediate CSG operations and the final CSG operation...in this case
the UNION was the final and the DIFFR were the intermediate.

The same idea applies to all CSG operations.  Composite is not a CSG but
it was the best place to put it. <grin>


* TEXTURES ON CSG OBJECTS *

To put a texture on a CSG object click on ENDF(using the Session command)
to make it the current object (you'll see ENDF at the bottom right part
of the screen) then click on TEXTURE to add the one that you want.


Transforming CSG /Composite objects

At this point it is NOT possible to transform (XFORM) the whole set of
objects.  You may XFORM any of the individual objects that compose a CSG
object.



Quick Comment

If you want to clip an object with 2 planes do the following:
1) Click on "intersection"
2) create the object to be clipped
3) create plane #1
4) create plane #2
5) rotate plane #2 so that the normal is facing oposite
   to plane #1's normal.  (When a plane is created, the normal
   is ALWAYS in the + direction of the axis.) Also you must translate
   plane #2 so they're not in the same place.

   Example:
   plane#1: PLANE_Y,Translate_Y = .5
   plane#2: PLANE_Y,Translate_Y = -.5,Rotate_Z = 180

   Plane #1's normal is pointing in the +Y direction, while
   plane #2's normal is in the -Y direction (due to rotation
              about Z of 180 degrees)

   Any object placed in the origin will be clipped at Y=0.5 and
   Y=-0.5 . Try it and see!


Creating PATH data files for your animations

This feature allows you to create data files of paths that may be
used in animations programs.  Simply select the Path menu and select
which curve to create.  These data files can be XFORMed in the same
fashion as any of the objects supported by POVCAD.

To create a curve, select the corresponding curve and you'll be asked
for a filename to save the data. This is done to reduce memory
requirements on your system.  The following is a brief description:

0) Load and SAVE
   Load read any 3D point ASCII file and converts it into a path,
   i.e. lines will be drawn to connect the points sequentially.  Your
   data file SHOULD NOT have an extension *.PTH since this is used by
   POVCAD to save the final path files.

   SAVE converts your data file, i.e. filename.ext into filename.PTH.
   Initially, filename.ext was a set of 3D points that you created
   yourself or thru POVCAD.  Since you may want to rotate, scale or
   translate the data, POVCAD takes those operations and changes your
   data.  In order to keep the original data intact, POVCAD saves the
   new data with the PTH extension.

   The EXPORT to POV function in the FILE menu also creates the *.PTH
   files.  If you haven't created any 3D objects and you don't need to
   create a POV file, simply use the SAVE function in the PATH menu, to
   save your animation files.

   To merge 2 or more data files, drop to DOS or load a texteditor
   and simply append one file to the other to create more complicated
   path data files.  It's that simple! (gasp!...I hope it works)


1) Freehand
   Converts a set of points created on the screen to a path.  Maximum
   number of points is 25 (at this point at least)

2) Linear
   Click 2 points (more than that will be discarded) on the screen.
   The routine will subdivide the line segment into a set of points.

3) Circular
   Creates a circular path.  No points have to be created with the
   mouse.

4) Parabolic
   Follows the curve Y = aX^2 where a is the parabola coefficient
   and the value of Y is the height.  The value of Z is zero but
   you may create this curve from any view.  The routines will swap
   the axis to reflect the view you're in.

5) Helix
   Creates a "spring".  The curve follows :
    x = a cos(2*pi*t)
    y = a sin(2*pi*t)
    z = t

    Therefore Z is the "height" of the function.  This depends on the
    current view setting.

After creating the curves you may use them to animate your raytraced
images.  POVCAD simply creates the curves and shows them with the
geometry so you have a better understanding of how things might look.
Remember, you can scale, rotate and translate the data like any other
object!  have fun!

Creating LightSources

To create a light_source object, click on the Light command in the main
menu.  Enter the origin coordinates of the light_source (x,y,z).  To
add a color to the light_source, select it (Session) then click on the
Color command in the main menu.  You may select any color or edit the
string "red # green # blue #" by replacing the "#" with appropiate numbers.
If you wish to move the light_source, click on XFORM and modify the
translate parameters.

The rotation angles do not apply to light_sources.  The scale factors will
only affect the size of the light_source symbol (resembles a 3D axis) in
POVCAD, POV does not require a scaling factor.


How does POVCAD save the objects?

POVCAD saves 3 files for every session: {(4) is optional }
1) *.CAD   This is the object definitions file
2) *.TEX   file with the textures of each object
3) *.WRL   world definition of the session
4) *.PTH   data files to be used in your animation programs

*.CAD file structure:
This is the format that POVCAD uses for those of you that want to create
external programs to deal with them.  The file is an ASCII file with
double quotes at the begining and end of each statement:

rx,ry,rz = rotations about each axis (absolute)
tx,ty,tz = translations on each axis
sx,sy,sz = scale factors for x,y and z

1) Plane:    "PLN axis rx ry rz tx ty tz sx sy sz"

Example:
"PLN X 0.0 0.0 0.0 0.0 0.0 0.0 1 1 1"

2) Cylinder  "CYL radius height rx ry rz tx ty tz sx sy sz"

Example:
"CYL .2 1 0.0 0.0 0.0 0.0 0.0 0.0 1 1 1"

3) Cone:     "CON radius height rx ry rz tx ty tz sx sy sz"

Example:
   "CON .2 1 0.0 0.0 0.0 0.0 0.0 0.0 1 1 1"

4) Sphere:   "SPH radius rx ry rz tx ty tz sx sy sz"
(tx ty and tz are the center of the sphere)
(sx sy sz must have the same value)

Example:
   "SPH .5 0.0 0.0 0.0 0.0 0.0 0.0 1 1 1"

5) Ellipsoid: "ELI xradius yradius zradius rx ry rz tx ty tz sx sy sz"

Example:
   "ELI .5 .2 .3 0.0 0.0 0.0 0.0 0.0 0.0 1 1 1"

6) Torus:     "TOR radius_major radius_minor rx ry rz tx ty tz sx sy sz"

Example:
   "TOR .7 .2 0.0 0.0 0.0 0.0 0.0 0.0 1 1 1"

7) Box:       "BOX rx ry rz tx ty tz sizex sizey sizez"
(the Box is a unit cube that has been scaled to size)

Example:
   "BOX 0.0 0.0 0.0 0.0 0.0 0.0 1 2 .1"

8) HeightField "HFL filename.ext rx ry rz tx ty tz sx sy sz"
(POVCAD draws a pyramid to represent it, with dimensions x=1 y=1 z=1,
 so it must be scaled properly.  Check POV's docs on height_field.)

Example
   "HFL mountain.gif 0.0 0.0 0.0 0.0 0.0 0.0 1000 1000 3245"

9) RAW: "RAW filename.ext rx ry rz tx ty tz sx sy sz"
   (Consider using Steve Anger's RAW2POV, it's more efficient. Don't
    say I didn't tell you about it!)
Example:
    "RAW sweep.dat 0.0 0.0 0.0 0.5 1.3 0.0 1 1 1"


10) Sweep
    (same as RAW only that the SWP keyword appears instead of RAW)


11) Path
    "PTH filename.ext 0.0 0.0 0.0 0.0 0.0 0.0 1 1 1"
    This command points to a file with the format:
     p1.x p1.y p1.z
     p2.x p2.y p2.z
     ....ect .....

    which was created with POVCAD or that you made up yourself.

12) Light Source
    "LTS 0.0 0.0 0.0 X Y Z .25 .25 .25"

    Comments:
     * The first three number are not used at all.
     * X Y Z refer to the light source position
     * the three .25 values are scaling factors that only affect
       the drawing on POVCAD.   You may change those numbers to
       suit your needs by using the XFORM command (scale x,y,z).
     * The light_source color is in the *.TEX file.


The *.TEX file structure:
The *.tex file has a line for every item in the *.cad file.  Some places
may be empty but the file length is the same as the *.cad file.  If you
created light_sources, the colors will appear here also.

The *.WRL file structure:
This file has 4 values (if it's not found in your directory, POVCAD
assumes a world definition of (-1,-1)-(1,1) ):

WXleft  WYbottom
WXright WYtop

These values correspond to the YX plane view.

The *.PTH file structure
This is a straight ASCII file with a list of 3D points:

p1.x p1.y p1.z
p2.x p2.y p2.z
... ect...

The data has already been transformed by any operations you might have
done inside POVCAD.


Other Stuff
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Limits
At this point up to 100 objects may be created.  You may do complicated
objects by MERGEing files.  This will change on future versions.

CSG/COMPOSITE Objects
You can not XFORM the whole CSG/COMPOSITE object...you may XFORM any of
the components.

World Coordinates Definition:
POVCAD starts with (-1,-1)-(1,1) => (lowerleftcorner)-(upperleftcorner).
Click on View and then World to change that or use the ZoomIn/Out icons
to scale up or down.  When you ZoomIn the world = world/scalefactor and
when you ZoomOut the world = world * scalefactor.

Pan
You can Pan(scroll) in all direction by clicking on the arrows.  You may
change the Pan Step Size to move faster or slower. Experiment with it.

Copy
The Copy function will create an exact copy of the current object. That
means that it will be also in the SAME place as the original.  Then XFORM
will be shown and select the transformation necessary to put the new object
where it should be.  Click on redraw to refresh the screen if necessary.

Files
The Export to POV creates a POV format file of the current scene.  The
default name is POVCAD.OUT...the name can be changed.  It also creates
any path files (*.PTH) that are in memory.

AutoRedraw ON/OFF
There's an icon to turn on/off the autoredraw feature.  With the option
on ON the drawing is sent to a buffer first and then appears on the screen.
With the option on OFF the screen will be redraw everytime that you select
the TEXTURE, SESSION or XFORM windows.  Experiment which one works best for you.
The important point is that in ON you pay a price with memory.  Check
with your system, you decide.

Things you must do on your own (Sorry!...at least for now)
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1) "spotlight" light sources and camera will be missing from the files.
2) If you forget to add textures to the objects you must add it later.
   (you can always reload the session file and put them in)

Suggestions
Create a standard view file with lightsources and camera and put
somewhere the statement #include "myscene.pov" to include your scene.
That's what I do and works OK for me.


Your Suggestions
I do welcome your comments and suggestions!  Registered users have a
better chance of seeing their comments incorporated in the program.
If you like it or not let me know!

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    REGISTRATION FORM FOR POVCAD 1.0  (c) Alfonso Hermida 1993

                COMPLETE THE REQUIRED INFORMATION
                    Send check or money order to
                         Alfonso Hermida
                       9346 Kings Grant Rd
                         Laurel MD 20723


Name   :_________________________________         Date:_________

Address:________________________________________________________

        ________________________________________________________

        ________________________________________________________


Phone  :__________________________________


Your registration entitles you to support thru Pi Square BBS.  Write
a temporary password to add your account to the BBS:

BBS password: _________________________


Would you be interested in the source code?  Yes[  ]   No[  ]
(written in Visual Basic 2.0)

Comments:__________________________________________________________

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