Ian & Stuart's Australian Mac: Not for Sale/Another.not.for.sale (Australia).iso/hold me in your arms/Virtual-Worlds/commercial/CDK_vs_WTK

Internet Message Format | 1993-05-02 | 25KB

Date: Sun, 2 May 1993 21:36:13 -0700
From: Kenneth Pimentel <[e-mail]>
Subject: SOFTWARE: Cyberspace Developer Kit (Autodesk) vs. WorldToolKit (Sense8)


I found this on the Amulet BBS and thought scivw readers might be
interested in it:
-------------------------------------------------------------------------

Originally written 4-23-93, last draft on 4-28-93

Ok, I know several people have been waiting for my comparison of
WTK(WorldToolKit) from Sense8 Corp. and CDK(Cyberspace Developer Kit)
from AutoDesk Inc. Since I first dropped a note on my favorite BBS
about having both products many people have expressed an interest in
hearing about my findings. Because of this enormous interest, I have
tried to write a very responsible report, sticking to simply the
facts. Although I do share some of my opinions, please keep in mind
that's what they are, opinions.

Who am I? My name is Jeffrey Donovan. l am forming a new startup
company in Sausalito and we are developing standalone VR applications
and 3rd party VR software libraries. I have been working with
WorldToolKit from Sense8 corp.  for awhile now, and prior to that was
writing my own pseudo-VR systems using wire-frame rendering only. I
have been programming in C for 8 years (my latest book "Building A
Better Mouse Trap, A Programmer's Guide To The Mouse", was released
this March from Osborne McGraw-Hill) and have been programming in C++
since Borland released C++ V1.0.

Because I have very limited time (I really need to get back to work),
and because I will try to cover as many issues as possible, there may
be some areas I do not cover in enough detail. Please leave me mail
about any item you would like a bit more info on.

Machine Used :
--------------
   I am currently using the products on a 486 66-mhz Compaq with 8 megs
   memory, 240 meg hd, NEC MultiSynch 5FG, SPEA fire board, PharLap 386
   DOS extender and compiling with the MetaWare 32-bit C/C++ compiler (a
   great compiler!). The only input devices I have used or tested to date
   are the keyboard and a standard 2-d mouse. The worlds I tested with both
   CDK and WTK ranged from 500 to over 10,000 polygons.

Style Of The Libraries:
-----------------------
   WTK is designed with C and a good OOP design in mind. With
   WorldToolKit from Sense8, a novice C programmer could probably start
   building their own exciting worlds in about 2-3 hours and pros will
   be flying the minute it's installed.

   CDK embraces C++ to the fullest extent. Fluency in C++ and all it's
   abstractions is required and it is not a product for inexperienced
   C++ programmers. If you are fluent in C++ you'll be up and flying
   quickly.

Functionality:
---------------
   WTK and CDK provide much of the same functionality you would expect
   in virtual libraries. So, instead of concentrating on every individual
   issue, I will do a comparison of the most obvious components I have
   found(or not found) so far.

   Portals:
   --------
   CDK has no portals. Although it's entirely possible to handle portalling
   yourself(a portal is a window to a different world), WTK provides a rich
   set of functions to handle this for you. You also have tremendous
   flexibility in WTK when moving thru different worlds by way of programmer
   defined entry and exit functions.

   Terrain:
   --------
   CDK offers no built in terrain functions. Terrain mapping and following
   can be extremely important depending on the virtual application, and
   again, while the programmer can handle this manually, I am disappointed
   that there are no built in terrain functions in CDK. With WTK it's one
   line of code and you can make either flat gridded terrain or FANTASTIC
   random terrain. I mean really great terrain! Then you can apply textures
   to that terrain and build some wild landscapes in just two function
calls.
   You can also read in your own terrain from an ASCII file and terrain
   following functions are built in as well.

   Backface Rejection:
   -------------------
   I have not yet discovered ANY method with CDK to allow flying into an
   object(individual objects) and viewing the interior. This may be due to
   the fact that the function to set backface rejection is not working
   properly, or that I am doing something wrong in CDK.

   Update
   4/27/93: The SPEA calls to set BackFace rejection were not implemented
            in this version of CDK and I was referred to the SPEA manual
            to look for their backface functions.

   Dynamic Objects and Properties:
   -------------------------------
   CDK provides more functions for dynamically creating geometric objects
   and handling physical properties. For instance, morphing objects with
   boolean functions, spring damping and friction functions, etc. WTK has
   several pre-defined geometric objects that are programmer definable, and
   I have found it very easy to build more complex objects as well. Physical
   properties are something missing from WorldToolKit and left up to the
   programmer, although if you know a bit of math implementing physical
   properties on a WTK object is extremely easy.

   Lighting:
   ---------
   CDK has better lighting qualities. Shininess can be applied to objects
   very easily, and this makes the worlds seem less cartoonish. I must say
   that the surface tables and lighting properties allow you to create some
   very "spooky" effects and some very real looking worlds. Lighting is also
   more controllable and you can set the color of light as well.

   VESA:
   -----
   CDK has the ability to run on VESA systems. Look for WTK to be supporting
   VESA by the next SIGGRAPH conf.

   Textures:
   ---------
   WorldToolKit offers a wealth of functions for textures. The textures are
   imported from TARGA files, and many commercially available paint
   programs (I use CorelDraw) have the capability to generate TARGA(*.TGA)
   files. This makes it EXTREMELY easy to create and use textures. Textures
   in WTK can also be solid or transparent, and the capability to add
   textures is something I consider essential for realistic applications,
   even more important than lighting. With textures, an object that is
   supposed to be made of wood can have a wood texture applied to it, and it
   becomes wood! With carefully applied textures, certain applications can
   also reduce the number of polygons needed for a specific object, because
a
   simpler object can be made and a texture applied instead of using many
   complex objects(more polygons) for full details. Rendering speed can
   increase dramatically with this trick. With WTK and the SPEA card texture
   application and manipulation speed is  nothing less than phenomenal.

   NOTE: The upcoming VESA version of WorldToolKit will be supporting
         textures as well.

   CDK has a class for textures(CyTexture), but it is a place-holder for
   future expansion on CDK. Currently CDK does not support textures on
   any platform.

   Attachments:
   ------------
   Both WTK and CDK offer functions to build complex models by attaching
   one object to another and defining how the objects interact with one
   another. Separate pivot points, rotational qualities, etc. can all be
   had thru attachments. WTK provides more functionality than CDK in
   regards to attachments(or assemblies).

   Opinion: Sense8 has thought out attachments more thoroughly than
            Autodesk, making it very, very intuitive, almost second
            nature.

   Animation:
   ----------
   Both WTK and CDK both provide animation sequences but I haven't used
   the auto-animate features of either yet.

   Paths:
   ------
   WorldToolkit offers you many functions for recording, saving, loading,
   interpolating, defining, rewinding, and managing paths.(A preset flight
   path through the world or by an object). I haven't gotten as deep as you
   can go with the paths but so far it's been easy. These features allows
   you or and end-user (if set up properly) to fly a preset course in the
   world for presentation  or special sequences. The paths can also be for
   individual objects and you can have multiple active paths. I haven't
   found any path functions in CDK.

   Distance Representation:
   ------------------------
   Both WTK and CDK provide functions for distant objects. What this
   means is that you can have a less detailed copy of an object and
   swap it for the detailed object when viewed at a specified distance.
   The big difference is that WTK gives you a function to create a less
   detailed object automatically and it will be indistinguishable from the
   original object when viewed from the specified distance. With CDK you
   must create the lesser detailed object. CDK provides a distance policy
   for automatic swapping, while it's up to the programmer to poll the
   distance and swap the objects in WTK.

   Supported File Types:
   ---------------------
   Both WTK and CDK can read a 3d DXF files with a single function call.
   CDK can also read 3d Studio files, but not the animation sequences.
   WorltToolKit also has it's own Neutral File Format. Basically this is
   an ASCII file that contains the objects' name, vertex list, polygon list,
   colors and optional polygon id #'s, shading properties, textures file
   names for individual polygons, portals, etc. Sense8 gives you detailed
   instructions for setting up the file and it's a snap. As I stated in the
   opening, I originally started writing my own pseudo-VR systems using wire
   frame modelling.  It took me 1 hour to figure out the WTK NFF format and
   spew my wire frame world(2400+ polygons) into a file WTK could read. To
   me, this is a very impressive feature, because your not limited to DXF
   or 3DS files. Any file type you can read can be converted into a file
   WTK can read. WorldToolKit also has functions to automatically convert
   NFF files to DXF files and vice-versa.

   As previously stated WTK also reads TARGA(.TGA) files for textures.

   AutoCAD:
   --------
   CDK has the ability to run concurrent with AutoCAD, but I have not
   tested any of these capabilities.

   Attached Data:
   --------------
   Both WTK and CDK allow programmer defined data to be attached to
   objects easily.

   Networking:
   -----------
   I have not yet written any multi-user virtual environments so I am
   not qualified to make any type of comparison here.

Speed:
------
   I have written several identical applications using WTK and CDK. WTK
   renders faster. With WorldToolkit, you can also improve speed in a
   multitude of ways including importing stationary geometry at startup
   and critical shading property functions. For instance, By loading a
   polygon file as stationary geometry instead of a dynamic object FPS
   speed increases about 4-5 fold. Additionally, you have a variety of
   options for enhancing speed of dynamic objects by setting shading,
   fastmerge and principal axis calculation flags. Speed enhancement can be
   as much as 3 fold depending on the method. I haven't found any functions
   of this type with CDK.

   I will not give any FPS quotes because they are always a bit subjective
   and besides, there's no way to retrieve the frame rate in CDK (that I
   have). WTK has a function to retrieve current FPS.

   CDK objects generate a bad flicker when viewed extremely close up and
   moving. WTK objects are smooth throughout and you will only experience
   flicker if you use the 800x600 mode due to the 2MB image copy from DRAM
   to VRAM(the SPEA board is not fast enough to do it in less than 1/30th of
   a second, so you end up with a potential flicker mid-screen when moving).
   In all other modes there is no flicker whatsoever, no matter how close
   you get to an object.

Documentation:
--------------
   Sense8: The documentation supplied with WTK from Sense8 is organized
   in a clear, concise manner. When you need to find an object function,
   look in the objects sections. When you need to find a light function,
   look in the light section, etc. Every issue is covered and easily
   retrievable.

   AutoDsk: The Autodesk manual follows no real format in regards to
   individual issues. The classes and functions are organized
   alphabetically only, so plan on jumping back and forth from section
   to section to find details on classes and associated functions. The
   index could also be improved dramatically.

Technical Support:
------------------
   Sense8 : Technical support is nothing less than superb. Fear of
   embarrassment has never stopped me from asking their staff any
   question no matter how obvious the answer may seem, and they
   have had an answer for every question without delay. They know
   their code!

   AutoDsk: Autodesk's policy remains that it is the resellers
   responsibility to provide technical support. While this may
   work sufficiently for commercial standalone applications, I don't
   think programmers will be satisfied. Not to degrade my reseller(he's
   a nice guy) but he couldn't write a line of code to save his life.
   When I want tech support I want to talk to programmers familiar with
   the product, not my nearest Computerland dealer who thinks BASIC is
   the language of choice. Autodesk needs to realize they are dealing
   with programmers now and act accordingly.

   Update
   4/27/93 - I originally wrote the last paragraph on 4/23/93. Well,
             after a bit of complaining to AutoDesk, somebody did give
             me a call and cleared up some confusion. I left this
             original document fairly unchanged, and have made date
             stamps of 4/27/93 by paragraphs of information where tech
             support helped. This does not in any way change my thinking
             in regards to AutoDesk's tech support. I shouldn't have had
             to get heated up(after waiting three days for an answer) and
             make those phone calls to get the help. It should be there
             ready and waiting.

Errors:
-------
   Sense8: I have been working with WTK Version 2.0(available commercially
   by the end of May). I started with the alpha version and am now working
   with beta. I have yet to find a function that doesn't work as documented
   with 2.0 beta and have used about 90 percent of the functions available
   on my platform.

   AutoDsk : 2 of the 3 CDK Display functions I have used so far do not work
   and if you use the SPEA card, your going to have to write some other mode
   -reset code, because the AutoDesk function to get out of graphics mode
   does not work. Wire-framing doesn't seem to work either. These problems
   exist not only in the code I have written, but in every example AutoDesk
   included as well. Additionally, some of the supplied examples included
   with CDK generate up to 50+ warnings. While some are of no consequence,
   I frown at code(especially commercial) that generates this many warnings.

   Update
   4/27/93 - Wire framing is not supported with CDK on the SPEA card,
             only VESA systems. Wire framing IS supported with WTK on
             the SPEA card. The graphics mode problem is also a known
             bug with CDK.

Code Example:
-------------
I thought I'd give you a small code example to sample the flavor of WTK
and CDK. This code will do the barest of tasks. It simply makes a universe
(or deck and space), sets up a mouse sensor, makes a single blue box of 100
units, makes a single light, sets up the viewport and moves it back so the
entire box is visible, and then goes into automatic simulation. Both
programs
respond to the mouse and both will quit when the letter 'q' is pressed.

This represents the simplest possible program to create and walkaround a
single dynamic object with a dynamic light source. This sample is NOT
intended in any way to demonstrate the capacities of either library, it
simply demonstrates the "flavor" of each. Assume all headers are in place
as well.

WorldToolKit Example:
---------------------
static void actions(void);

main(void)
   {
   WTviewpoint *worldview;            /* Universe viewpoint
*/
   WTsensor *mousesensor;             /* Mouse sensor
*/
   WTobject *box;                     /* Box object
*/
   WTlight  *light;                   /* Light object
*/
   WTp3 dir,midpt,pos;                /* Position direction mid
*/

   WTuniverse_new(0,0);               /* Create new universe
*/
   WTlight_setambient(0.15);
   WTuniverse_setbgcolor(0x000);
   WTuniverse_setrendering(WTRENDER_TEXTURED);

                                      /* Add a box to universe and set
colr*/
   box=WTobject_newblock(100.0,100.0,100.0,TRUE,FALSE);
   WTobject_setcolor(box,0x00a);
                                      /* Make a light, set it away from
box*/
   pos[X]=-50.0;pos[Y]=-50.0;pos[Z]=-200.0;
   dir[X]=0.0;dir[Y]=0.0;dir[Z]=1.0;
   light=WTlight_new(pos,dir,0.75);
                                      /* Get the universe viewpoint, move
*/
                                      /* move back out and then set view
*/
   worldview=WTviewpoint_copy(WTuniverse_getviewpoint());
   WTviewpoint_getdirection(worldview,dir);
   WTs_multp3(WTuniverse_getradius()*2.0,dir);
   WTuniverse_getmidpoint(midpt);
   WTp3_subtract(midpt,dir,pos);
   WTviewpoint_setposition(worldview,pos);
   WTuniverse_setviewpoint(worldview);

                                      /* Get mouse sensor, attach it to
*/
                                      /* universe view and set rates
*/
   mousesensor=WTsensor_new(WTmouse_open,WTmouse_close,WTmouse_moveview2,
                            NULL,1,WTSENSOR_DEFAULT);
   WTviewpoint_addsensor(worldview,mousesensor);
   WTsensor_setsensitivity(mousesensor,0.04*WTuniverse_getradius());
   WTsensor_setangularrate(mousesensor,PI/8.0);

   WTuniverse_setactions(actions);    /* Set action function event-hndler
*/

   WTuniverse_ready();                /* Prep universe and run simulation
*/
   WTuniverse_go();

   WTuniverse_delete();               /* Delete it all and exit
*/
   return(0);
   }

static void actions(void)
   {
   int ch;                            /* Scan for 'q' char and stop if so
*/
   if (kbhit()){ch=getch();if (ch=='q') WTuniverse_stop();}
   }

Cyberspace Developer Kit Example:
---------------------------------

CySensor6d *choose_sensor(const char *);
CyDisplay3d *choose_display(const char *disp, Real range);

main(void)
   {
   CyDisplay3d *display;              // Display object
   CyDeck *deck;                      // Deck    object
   CySpace *space;                    // Space   object
   CySurface *surface;                // Surface description
   CySurfaceTable *stable;            // Surface table
   CyColor specular,diffuse,ambient;  // Surface color tables
   CyComponent *boxobj;               // Box component
   CyCompInst *boxci;                 // Box component instance
   CySimObj *box;                     // Box simulation oject
   CyLight *light;                    // Single light
   CyBbox *boundbox;                  // Component bounding box
   CyVertex3 boxcenter;               // Center for bounding box
   Real maxd;                         // Max diminsion

   CySensor6d *mousesensor;           // Mouse sensor
   CyMouseView *mouseview;            // Mouse viewpoint
   CyPlatformView *platform;          // Viewer platform

   deck = new CyDeck();               // Make deck and space and get
   space= new CySpace();              // the mouse sensor.
   deck->SetSpace( space );
   mousesensor=choose_sensor("SENSOR1");
   deck->AddSensor(mousesensor);

   light= new CyLight();             // Make a light, set it away from box
   light->SetLightType(CY_SPOT);     // that is built later
   light->SetPosition(CyVertex3(50.0,50.0,-200.0));
   light->SetAim(CyVector3(0.0,0.0,1.0));
   light->SetColorRGB(1.0,1.0,1.0);
   light->SetMag(1.0);
                                     // Set up a surface table so we
                                     // can use our own colors.
   specular.r=0.0;specular.b=1.0;specular.g=0.0;
   diffuse.r=0.0;diffuse.b=1.0;diffuse.g=0.0;
   ambient.r=0.0;ambient.b=1.0;ambient.g=0.0;
   surface=new CySurface(0.5,0.5,1.0,0.1,1.0,&ambient,&diffuse,&specular);
   stable =new CySurfaceTable(2);
   stable ->SetSurface(1,surface);
                                    // Build the box and add to
                                    // simulation.
   boxobj=new CySolBox(100.0,100.0,100.0,1);
   boxci =new CyCompInst(boxobj);
   box   =new CySimObj(boxci);
   space->AddSimBase(box,SP_PHYSOBJ);

   boundbox = boxobj->GetBbox();      // Get bounding box
   boxcenter= boundbox->Centroid();   // and properties.
   maxd     = boundbox->MaxDim();
                                      // Auto set display and set
                                      // limits, perspective, surface
                                      // table and light
   display =choose_display("DISPLAY", 10 * maxd);
   display->SetPersp(40.0, 1.333, 0.01, 9 * maxd);
   display->SetSurfaceTable(stable);
   display->AddLight(light);
   deck->AddDisplay(display);
                                      // Now make a platform for viewer
                                      // and set it away from box, then
                                      // set platform/sensor speed
   platform = new CyPlatformView(boxcenter - (maxd * 4) * CyVector3(0,0,1),
                                 boxcenter, CyVector3(0, 1, 0), display,
                                 mousesensor);
   platform->SetSpeed(maxd * 0.04);
   space->AddSimBase(platform, SP_VIEWERS);

   mouseview= new CyMouseView();     // Attach mouse to platform view

   deck->Run();                      // Run the simulation, exit on 'q' char

   delete light;                     // Delete it all and exit
   delete mouseview;
   delete platform;
   delete box;
   delete boxci;
   delete boxobj;
   delete surface;
   delete stable;
   delete display;
   delete mousesensor;
   delete space;
   delete deck;

   return EXIT_SUCCESS;
   }

Code Notes:
-----------

In the above WorldToolKit code listing, the lines -

   worldview=WTviewpoint_copy(WTuniverse_getviewpoint());
   WTviewpoint_getdirection(worldview,dir);
   WTs_multp3(WTuniverse_getradius()*2.0,dir);
   WTuniverse_getmidpoint(midpt);
   WTp3_subtract(midpt,dir,pos);
   WTviewpoint_setposition(worldview,pos);
   WTuniverse_setviewpoint(worldview);

could have been changed to one line that read-

   WTviewpoint_zoomall(worldview);

I left it the long version so you could better compare the WTK viewpoint
method and the CDK platform view method. Although the methods are
different, they are also still quite similar, and with WTK the bounding
box method could have been used as well. Both have a variety of other
methods to accomplish the task.

*** A 3d DXF file walkaround program can be done with the same amount of
code in WTK and CDK.

Overall Opinion:
---------------
   WorldToolKit lets you program more intuitively to the task, and I
   find CDK's virtual abstractions somewhat confusing. However, both
   WTK and CDK do allow a good programmer to get deep enough to do
   anything. If development time is a big concern, you'll be flying
   faster with WTK.

   WorltToolKit from Sense8 leaves me with the impression of being written
   by people who have a wealth of experience with programming virtual
   worlds and thinking about virtual implementation(both programmer and
   end user). Sense8 has incorporated more thought into ease of programmer
   implementation, and WorldToolKit is VERY coherent. Sense8 has also had
   more time to listen to programmer feedback and react accordingly. Their
   libraries are error free and work as specified.

   CDK from AutoDesk leaves me with the impression of being rushed to
   market too fast just to be the only VESA version for the time
   being(although we've all heard about it for quite some time,
   it doesn't seem to have been tested thouroughly enough, especially
   on the SPEA card). Autodesk also seems to have devoted more time to
   designing features for tight integration with AutoCAD than developing
   standalone virtual worlds. The product has several errors I have found so
   far, most having to do with the SPEA card. I still have yet to receive a
   VESA driver that CDK supports(my last one is the V7VESA.COM and it's
   about a year old), but I should have a new one soon and will leave an
   update regarding that.

   Please, if you disagree with any of my statements or have some
   questions about either product, don't hesitate to leave me mail. I
   can be reached at The Amulet BBS [phone] in The Virtual
   Forum(forum #1).

   Jeffrey S. Donovan