plib-users

Re: [Plib-users] ssgAux objects

[Steve B. <sjb...@ai...>]

Justin Geo Zaun wrote:
> I'm sure I'm missing something, but I would like to add some more 
> shapes to my application. I'de like a pyramid first and it should work 
> basically like ssgaCube does. I've looked through the code but can't 
> find code for the cube. I was wondering if anyone had an example class 
> I could look at?

Well, the code for the cube is in plib/src/ssgAux/ssgaShapes.{cxx,h}

There is an example of the use of an ssgaCube in
plib/examples/src/ssg/water/water.cxx

---------------------------- Steve Baker -------------------------
HomeEmail: <sjb...@ai...>    WorkEmail: <sj...@li...>
HomePage : http://www.sjbaker.org
Projects : http://plib.sf.net    http://tuxaqfh.sf.net
            http://tuxkart.sf.net http://prettypoly.sf.net
-----BEGIN GEEK CODE BLOCK-----
GCS d-- s:+ a+ C++++$ UL+++$ P--- L++++$ E--- W+++ N o+ K? w--- !O M-
V-- PS++ PE- Y-- PGP-- t+ 5 X R+++ tv b++ DI++ D G+ e++ h--(-) r+++ y++++
-----END GEEK CODE BLOCK-----

[Plib-users] ssgAux objects

[Justin G. Z. <jz...@ca...>]

I'm sure I'm missing something, but I would like to add some more 
shapes to my application. I'de like a pyramid first and it should work 
basically like ssgaCube does. I've looked through the code but can't 
find code for the cube. I was wondering if anyone had an example class 
I could look at?

Justin

Re: sec:uRe: [Plib-users] ssgaSky and Scaling ofthe scene

[Michael W. <mic...@ti...>]

Hi Nick,

I have multiplied all sky and clouds parameter with 0.001,alo the span
parameter. .

I have found in the source for building the clouds the parameter scale =
4000.
Do you know what it's mean.

 Best regards

Michael
----- Original Message ----- 
From: "Nick McEvoy" <nic...@ka...>
To: <pli...@li...>
Sent: Tuesday, August 10, 2004 5:19 AM
Subject: sec:uRe: [Plib-users] ssgaSky and Scaling ofthe scene


> What are your sky settings ?
>
> Example:
> sky->build(80000, 80000, nplanets, planet_data, nstars, star_data);
> sky->addCloud(*"data/scattered.rgba"*, /// texture
> /              80000,                 /// span
> /              3000,                  /// elevation,
> /              100,                   /// thickness
> /              100);                  /// transition
>
> /I assume you have reduced the h_radius & v_radius parameters for build(),
> thus have you also reduced the addCloud() 'span' parameter ?
>
> Cheers,
> Nick
>
> Michael Wessels wrote:
>
> >Hi all,
> >I am using ssgSky to build the sky in my simulation. I have build it from
> >the sky-example of plib.
> >My problem is now:
> >The scene is build in the dimension 'kilometer' and the sky and his
objects
> >in demension 'meter'. The sky looks very good. But my airplane never can
fly
> >over the clouds.
> >If I reduce the scaling of the sky and his objects to the dimension
> >'kilometer' the clouds come to near and not scattered.
> >
> >How can I combine the dimension 'kilometer' in the scene with the
dimension
> >'meter' of the sky ?
> >
> >Michael
> >
> >
> >
> >-------------------------------------------------------
> >This SF.Net email is sponsored by OSTG. Have you noticed the changes on
> >Linux.com, ITManagersJournal and NewsForge in the past few weeks? Now,
> >one more big change to announce. We are now OSTG- Open Source Technology
> >Group. Come see the changes on the new OSTG site. www.ostg.com
> >_______________________________________________
> >plib-users mailing list
> >pli...@li...
> >https://lists.sourceforge.net/lists/listinfo/plib-users
> >
> >
>
>
>
> -------------------------------------------------------
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sec:uRe: [Plib-users] ssgaSky and Scaling ofthe scene

[Nick M. <nic...@ka...>]

What are your sky settings ?

Example:
sky->build(80000, 80000, nplanets, planet_data, nstars, star_data);
sky->addCloud(*"data/scattered.rgba"*, /// texture
/              80000,                 /// span
/              3000,                  /// elevation,
/              100,                   /// thickness
/              100);                  /// transition

/I assume you have reduced the h_radius & v_radius parameters for build(),
thus have you also reduced the addCloud() 'span' parameter ?

Cheers,
Nick

Michael Wessels wrote:

>Hi all,
>I am using ssgSky to build the sky in my simulation. I have build it from
>the sky-example of plib.
>My problem is now:
>The scene is build in the dimension 'kilometer' and the sky and his objects
>in demension 'meter'. The sky looks very good. But my airplane never can fly
>over the clouds.
>If I reduce the scaling of the sky and his objects to the dimension
>'kilometer' the clouds come to near and not scattered.
>
>How can I combine the dimension 'kilometer' in the scene with the dimension
>'meter' of the sky ?
>
>Michael
>
>
>
>-------------------------------------------------------
>This SF.Net email is sponsored by OSTG. Have you noticed the changes on
>Linux.com, ITManagersJournal and NewsForge in the past few weeks? Now,
>one more big change to announce. We are now OSTG- Open Source Technology
>Group. Come see the changes on the new OSTG site. www.ostg.com
>_______________________________________________
>plib-users mailing list
>pli...@li...
>https://lists.sourceforge.net/lists/listinfo/plib-users
>  
>

[Plib-users] ssgaSky and Scaling ofthe scene

[Michael W. <mic...@ti...>]

Hi all,
I am using ssgSky to build the sky in my simulation. I have build it from
the sky-example of plib.
My problem is now:
The scene is build in the dimension 'kilometer' and the sky and his objects
in demension 'meter'. The sky looks very good. But my airplane never can fly
over the clouds.
If I reduce the scaling of the sky and his objects to the dimension
'kilometer' the clouds come to near and not scattered.

How can I combine the dimension 'kilometer' in the scene with the dimension
'meter' of the sky ?

Michael

[Plib-users] PUI Menubar functionality extensions

[<ra...@EE...>]

Hi,

I would like to use such features as menu tabs that have entries which expand rightwards, ie the puPopupMenu's puOneshot will call another puPopupMenu with more options.

For example, in internet explorer, the View->Text Size expands rightwards to enable you to select more options.

I am having trouble getting the x and y coordinates of the puOneshot which I want to expand rightwards. What I am doing now is calling the GetFirstChild() of the puMenuBar, then searching through the list:
while (next!=NULL) { 
   next = next->getNextObject();
   ...
   more code
   ...
}

After finding the appropriate object (I check by comparing the legend field to what I want to search for, ie  
if (strcmp(next->getLegend(), search_legend)==0) break;

then I call the next->getPosition() and next->getSize() and calculate the appropriate place to set the puPopupMenu, ie using popup_menu->setPosition(...)

Right now the coordinates I am getting back are x=246 and y=-24, I am not sure what kind of coordinate system the PUI lib uses, but the popUpMenu is not appearing in the right place.

I am completely new to GLUT, OpenGL, so maybe I have missed something obvious.

Any suggestions on what I can do or change to get this functionality?
Thanks alot for any help!

Rach Liu

Re: [Plib-users] Plib failes to build on my system

[cedric <ced...@so...>]

On Thursday 29 July 2004 19:10, Thomas Rebien wrote:
> On Thursday 29 July 2004 21:03, cedric wrote:
> > i tried to build plib, but i was unsuccesful.
> >
> > /usr/include/GL/glx.h:39:22: X11/Xlib.h: No such file or directory
> > /usr/include/GL/glx.h:40:23: X11/Xutil.h: No such file or directory
>
> Looks like you are missing the X11 header files.
> If you have them installed in some nonstandard directory, try setting
>
> export CPPFLAGS=-I<path to X11 include dir>
>
> and excecute ./configure again.
>
> Regards,
>
> Thomas
>
>
> -------------------------------------------------------
> This SF.Net email is sponsored by OSTG. Have you noticed the changes on
> Linux.com, ITManagersJournal and NewsForge in the past few weeks? Now,
> one more big change to announce. We are now OSTG- Open Source Technology
> Group. Come see the changes on the new OSTG site. www.ostg.com
> _______________________________________________
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To get it in the archives:
export CPPFLAGS='-I /usr/X11R6/include/'

Thanks!
cedric
-- 
The only dumb question is the one omitted

De enige domme vraag is degene die niet gesteld wordt

Re: [Plib-users] Plib failes to build on my system

[Thomas R. <tho...@gm...>]

On Thursday 29 July 2004 21:03, cedric wrote:
> i tried to build plib, but i was unsuccesful.

> /usr/include/GL/glx.h:39:22: X11/Xlib.h: No such file or directory
> /usr/include/GL/glx.h:40:23: X11/Xutil.h: No such file or directory

Looks like you are missing the X11 header files. 
If you have them installed in some nonstandard directory, try setting 

export CPPFLAGS=-I<path to X11 include dir>

and excecute ./configure again.

Regards,

Thomas

Re: [Plib-users] Plib failes to build on my system

[Steve W. <st...@sh...>]

On Thu, 29 Jul 2004, cedric wrote:

> /usr/include/GL/glx.h:39:22: X11/Xlib.h: No such file or directory
> /usr/include/GL/glx.h:40:23: X11/Xutil.h: No such file or directory

Looks like your worst problem is the lack of the X11-devel headers.  I'd
fix that first, and see what else goes wrong after that...

[Plib-users] Plib failes to build on my system

[cedric <ced...@so...>]

Hi all,
i tried to build plib, but i was unsuccesful. 

my specs:
[_plib@lfs ~/plib-1.8.3]$ gcc -v
Reading specs from /usr/lib/gcc-lib/i686-pc-linux-gnu/3.3.2/specs
Configured with: ../gcc-3.3.2/configure --prefix=/usr --enable-shared 
--enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu 
--enable-languages=c,c++ : (reconfigured) ../gcc-3.3.2/configure 
--prefix=/usr --enable-shared --enable-threads=posix --enable-__cxa_atexit 
--enable-clocale=gnu --enable-languages=c,c++
Thread model: posix
gcc version 3.3.2
[_plib@lfs ~/plib-1.8.3]$ uname -a
Linux lfs 2.6.7 #1 Sat Jun 26 14:30:34 Local time zone must be set--see zic 
manu i686 GenuineIntel unknown GNU/Linux
[_plib@lfs ~/plib-1.8.3]$


The error:
make[2]: Entering directory `/storage/home/_plib/plib-1.8.3/src/pui'
source='pu.cxx' object='pu.o' libtool=no \
depfile='.deps/pu.Po' tmpdepfile='.deps/pu.TPo' \
depmode=gcc3 /bin/sh ../../depcomp \
g++ -DPACKAGE=\"plib\" -DVERSION=\"1.8.3\" -DHAVE_LIBPTHREAD=1 -DHAVE_LIBGL=1 
-D
HAVE_LIBDL=1 -DSTDC_HEADERS=1  -I. -I.  -I../../src/sg -I../../src/fnt 
-I../../s
rc/util   -g -O2 -Wall -c -o pu.o `test -f pu.cxx || echo './'`pu.cxx
In file included from pu.cxx:31:
/usr/include/GL/glx.h:39:22: X11/Xlib.h: No such file or directory
/usr/include/GL/glx.h:40:23: X11/Xutil.h: No such file or directory
In file included from pu.cxx:31:
/usr/include/GL/glx.h:51: error: syntax error before `;' token
/usr/include/GL/glx.h:52: error: syntax error before `;' token
/usr/include/GL/glx.h:53: error: syntax error before `;' token
/usr/include/GL/glx.h:54: error: syntax error before `;' token
/usr/include/GL/glx.h:55: error: syntax error before `;' token
/usr/include/GL/glx.h:56: error: syntax error before `;' token
<snip for size>
/usr/include/GL/glx.h:192: error: parse error before `,' token
/usr/include/GL/glx.h:192: error: `glXReleaseTexImageARB' declared as function
   returning a function
/usr/include/GL/glx.h:193: error: `Display' was not declared in this scope
/usr/include/GL/glx.h:193: error: `dpy' was not declared in this scope
/usr/include/GL/glx.h:193: error: parse error before `,' token
/usr/include/GL/glx.h:193: error: `glXDrawableAttribARB' declared as function
   returning a function
/usr/include/GL/glx.h:208: error: syntax error before `*' token
distcc[3669] ERROR: compile on localhost failed
make[2]: *** [pu.o] Error 1
make[2]: Leaving directory `/storage/home/_plib/plib-1.8.3/src/pui'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/storage/home/_plib/plib-1.8.3/src'
make: *** [all-recursive] Error 1

Did i provide enough information?

Regards, 

cedric
-- 
The only dumb question is the one omitted

De enige domme vraag is degene die niet gesteld wordt

Re: [Plib-users] Buiding Sky using the functions in ssgaSky

[Nick M. <nic...@ds...>]

Thats good news !!!

I wish you luck in your simulation !

Cheers,
Nick

Michael Wessels wrote:

>Hi Nick,
>
>I have found the solution. In a part of my code for initialisation of OpenGL
>I had the the statements
>glEnableClientState(GL_VERTEX_ARRAY);
>glEnableClientState(GL_NORMAL_ARRAY);
>
>I deleted these lines and now all runs well.
>
>Best regards
>
>Michael
>  
>

R: [Plib-users] Re: Plib as a Model Loader

[Paolo L. <p.l...@ci...>]

Juhana Sadeharju wrote:
> ...
> Do all this discussion mean that there is no standard 
> scenegraph nor good object/scenegraph loader which Tyler 
> could have used in the first place?

Try looking at http://lib3ds.sourceforge.net/. It is a library which
loads a 3DS model file with a single call, returning a (very complex)
structure with all information/data read. Then one have to walk down
this structure and generate <your-scenegraph> nodes accordingly. It's
something similar to the work to use Plib/SSG just as a model loader.

> How SSG compares to www.opensg.org or www.openscenegraph.{org,com}?

Lib3DS is *the* 3DS loader in OpenSceneGraph, don't know about OpenSG.

An accurate comparison with Plib/SSG is out of my capability, yet I
think SSG is generally simpler to use, it has a neat interface,
employes, yet doesn't stress, the OO paradigm, thus allowing non-top
skilled programmers to approach it with easy and success. On my opinion
having too much resources in a large library leads to disorientation at
startup, making you feeling to miss the better way to do your task.
Nevertheless Plib/SSG has a lot of useful possibilities behind the
scenes (i.e. no need to complicate the first approach), and can/will
certainly be improved.
Regarding loaders SSG is second to none, yet uses its own 3DS loader
instead of Lib3DS. The OpenFlight loader is also very good, but the
format itself is probably not devoted to low-budget games. Not to
mention the ability to save all the scene content in a single .ssg file,
which is then very efficient to load despite of the large size, and
allows to distribute an application in a compact, quite close, way.

Greetings -

Paolo

[Plib-users] Re: Plib as a Model Loader

[Juhana S. <ko...@ni...>]

>From: "Tyler Ohlsen" <Xa...@ho...>
>
>That being said, it would be nice to have the option to use someone
>else's scene graph library.  Not that yours is lacking in anything, but
>the option is nice.

That is simple with a scenegraph-to-scenegraph converter.
The problem cases such as LODs and billboards need to be stored
as LODs and billboards of the other scenegraph. No camera
matrix required here.

Neither scenegraphs cannot be rendered directly if they contain
the problem cases. Otherwise the scenegraph with, e.g., bounding
boxes/spheres is still good to have.

Do all this discussion mean that there is no standard scenegraph
nor good object/scenegraph loader which Tyler could have used in
the first place? How SSG compares to www.opensg.org or
www.openscenegraph.{org,com}?

Juhana
-- 
  http://music.columbia.edu/mailman/listinfo/linux-graphics-dev
  for developers of open source graphics software

Re: [Plib-users] STATES

[Steve B. <sjb...@ai...>]

Manuel Pecero Rodr=EDguez wrote:
> Ok, but I need to change the state (I need an state selector for this=20
> object) and if I make it with an ssgEntity * I cannot do it becouse wit=
h=20
> the ssgEntity class you cannot acces to the ssgLeaf states without a=20
> casting. isn=B4t it?

Ah!  OK - I see the cause of your confusion.

The ssgLoad function(s) don't generate a single leaf node - they generate=

an entire sub-tree of branch nodes with numerous leaf nodes under them.

In order to change the states of ALL of those leaf nodes you have to do
one of two things.  EITHER:

1) After you load the model, traverse the tree structure by testing
    each node to see whether it's a leaf or a branch (use 'isAKindOf())
    If it's a leaf, change it's state.  If it's a branch use getNumKids()=

    and getKid(n) to find all of it's child nodes - and call the tree tra=
verser
    recursively for each of them.

2) You can use a callback function (it's provided in the ssgLoaderOptions=
)
    that calls your code as the model is being loaded in order that you c=
an
    allocate your own ssgSimpleState nodes instead of the loader doing it=

    for you.

Which of these things to do depends on the context and what other things
you may need to change in the model that was loaded.

---------------------------- Steve Baker -------------------------
HomeEmail: <sjb...@ai...>    WorkEmail: <sj...@li...>
HomePage : http://www.sjbaker.org
Projects : http://plib.sf.net    http://tuxaqfh.sf.net
            http://tuxkart.sf.net http://prettypoly.sf.net
-----BEGIN GEEK CODE BLOCK-----
GCS d-- s:+ a+ C++++$ UL+++$ P--- L++++$ E--- W+++ N o+ K? w--- !O M-
V-- PS++ PE- Y-- PGP-- t+ 5 X R+++ tv b++ DI++ D G+ e++ h--(-) r+++ y++++=

-----END GEEK CODE BLOCK-----

Re: [Plib-users] Plib as a Model Loader

[Steve B. <sjb...@ai...>]

Tyler Ohlsen wrote:

> Loading from a 3D file into a scene graph is one implementation, you
> don't have to do it that way.  I agree that it makes a lot of sense and
> that most 3D applications are greatly improved by using scene graphs.
> That being said, it would be nice to have the option to use someone
> else's scene graph library.  Not that yours is lacking in anything, but
> the option is nice.

What other kind of data structure could you load a 3D model into?

A big pile of unstructured polygons and vertices I suppose - but that
isn't going to make rendering very easy - and it throws away a lot of
valuable information from the source model.

>>SSG lets you set both the modelview and projection matrix directly.
>>
>>It's hard to imagine what "your own camera" could be that SSG couldn't
>> already handle.
> 
> Again, this was a matter of preference.  I would like to use my own
> camera if I could (without doing a hack to convert my camera's
> orientation representation to ssg's camera orientation every frame).

What hack?   Just call the SSG function to pass your camera's data
(heading, pitch, roll, x, y, z) into SSG.  That's *ONE* line of code!

It couldn't be much simpler!

>>No - because SSG needs to know that those matrices are in order to
>>do field-of-view culling, Range-switched nodes and such.   OK - we
>>*could* read those matrices back from OpenGL in order to find out
>>what your camera code set them to - but reading things back from
>>OpenGL is something to be avoided at all costs.
> 
> But if you're not using ssg as your scene graph (just as a model loader)
> then you don't want it to do view culling.  Then ssg doesn't need to
> know the current state of these matrices at all.

OK - so if you aren't using SSG to render the scene and you don't
want the loaders to load into SSG's scene graph - then why the heck
are you using SSG?

>   glNewList(iListID, GL_COMPILE);
>   glPushMatrix();
>   glRotatef(-90, 1,0,0);            //ssgRawDraw allows for regular
> opengl transforms
>   glScalef(0.25f, 0.25f, 0.25f);
>   ssgRawDraw(oModel);
>   glPopMatrix();
>   glEndList();

But this mythical 'ssgRawDraw' function has to traverse the scene
graph because the scene graph may contain transforms, selectors,
animations and level-of-detail nodes that the loader created for
us.

Let's look at just one of those things by way of example: Level
of detail nodes (ssgRangeSelector).   This is something that has
been created by the loader from information in the model file.
It is a model that has one polygonal representation when it's
close to the eye - and a simpler one when it's further away.

If you ignore the presence of that node in the file and just
render all the polygons mindlessly then you'll see TWO copies
of the model being drawn at once - one of which looks really
bad when it's close to the eyepoint because it's made of so
few polygons - and the other of which will overload your system
because it's drawn with so many polygons - even when it's 10 miles
away from the camera.

So in that case, you **MUST** traverse the scene graph that the
loader built for you or the scene won't look right.

Now - in order to decide which of those two models to draw, your
rendering code (marked here in your example as 'ssgRawDraw') **MUST**
be able to figure out the range from the object to the camera.

However, it has no way to do that because you only gave the
camera matrix to OpenGL - you didn't tell the renderer.

The *ONLY* way that ssgRawDraw could possibly figure out that range
would be to do a glGetMatrix.   The trouble with glGetMatrix is that
it (potentially) stalls the graphics pipe...this could make it
UNBELIEVABLY slow.

So - the rational way to do it is to have your application pass the
camera matrix into SSG so that it knows where the camera is without
having to read it out of OpenGL....and that's what we have.

There simply isn't any other way to make this work.

There are other nodes that need this information - ssgCutout for
example.

Then there is the issue of field-of-view culling.  In a typical
application, the camera's field of view is something like 60x40
degrees.  That means that we are only rendering about a tenth of
the objects in the scene on a 'typical' setup.

If your 'ssgRawDraw' isn't doing field-of-view culling then it's
going to run something like ten times slower than ssgCullAndDraw
for the same scene.

However, the only way you can possibly do field of view culling
is if you know where the camera is...same problem.

It is UTTERLY trivial to modify any program that computes a
camera position and passes it to OpenGL to pass that position
into SSG instead.  Truly - it can't take you more than 5 lines
of code.  Heck - you could even to a glGetMatrix yourself if you
couldn't figure any other way.   When you take that little baby step,
everything else runs at least 10x faster than what you propose
- and it also gets things like level-of-detail and billboards right.

---------------------------- Steve Baker -------------------------
HomeEmail: <sjb...@ai...>    WorkEmail: <sj...@li...>
HomePage : http://www.sjbaker.org
Projects : http://plib.sf.net    http://tuxaqfh.sf.net
            http://tuxkart.sf.net http://prettypoly.sf.net
-----BEGIN GEEK CODE BLOCK-----
GCS d-- s:+ a+ C++++$ UL+++$ P--- L++++$ E--- W+++ N o+ K? w--- !O M-
V-- PS++ PE- Y-- PGP-- t+ 5 X R+++ tv b++ DI++ D G+ e++ h--(-) r+++ y++++
-----END GEEK CODE BLOCK-----

RE: [Plib-users] Plib as a Model Loader

[Tyler O. <Xa...@ho...>]

> Tyler Ohlsen wrote:
> > I'm looking at using plib as a model loader for a flight simulator 
> > type application I'm making, but that's all I want plib for.  (I
don't 
> > want to use plib as my scene graph library)
> 
> The problem with 3D file loaders is that they have to load the model
into 
> some kind of data structure.  The name for that data structure is a
> "Scene Graph".  Hence, loaders for 3D file formats cannot exist wihout

> a scene graph.  Since rendering stuff out of that scene graph is an 
> easily automatable process - and since it makes a lot of sense to use
> a C++ class hierarchy to do the work, it follows that the renderer and

> the file loader are tightly knitted together.
> 
> Tossing out the renderer in order to get the loaders is not generally
a good idea.

Loading from a 3D file into a scene graph is one implementation, you
don't have to do it that way.  I agree that it makes a lot of sense and
that most 3D applications are greatly improved by using scene graphs.
That being said, it would be nice to have the option to use someone
else's scene graph library.  Not that yours is lacking in anything, but
the option is nice.

> > I've played around with the simple scene graph module and I see that

> > calling ssgCullAndDraw throws out the existing projection and 
> > modelview matrices forcing you to use ssg's camera.  I would like to

> > use my own camera and not have to use ssg's camera at all.
> 
> SSG lets you set both the modelview and projection matrix directly.
> 
> It's hard to imagine what "your own camera" could be that SSG couldn't
already handle.

Again, this was a matter of preference.  I would like to use my own
camera if I could (without doing a hack to convert my camera's
orientation representation to ssg's camera orientation every frame).

> > Is there a way to call a draw method of an ssgRoot object that does 
> > not throw out the these matrices and leaves the view culling up to
the 
> > application (it just draws around the current zero point like 
> > glutSolidTeapot and such)?
> 
> No - because SSG needs to know that those matrices are in order to
> do field-of-view culling, Range-switched nodes and such.   OK - we
> *could* read those matrices back from OpenGL in order to find out
> what your camera code set them to - but reading things back from
> OpenGL is something to be avoided at all costs.
> 
> So it's better for you tell use what you want them to be and let
> us send them to OpenGL...that's no different from you sending them
> to OpenGL - but this is more efficient.

But if you're not using ssg as your scene graph (just as a model loader)
then you don't want it to do view culling.  Then ssg doesn't need to
know the current state of these matrices at all.

> >  If there doesn't exist such a method, would
> > there be an interest for me to create one for you all?
> 
> I don't see any conceivable need for that - but if you 
> can come up with something convincing, we could certainly consider it.

I dug into ssg and came up with the following code.  First is an example
usage of what this function gives the application programmer.  This
function has made the integration of ssg (just as a model loader and not
a scene graph) into my application much easier.  It may not be the most
efficient way to do it, but it's not too bad (I know that each leaf's
opengl state is forced).

Example Usage:
---------------------------------
int LoadModel(const char* szFile)
{
  int        iListID = glGenLists(1);
  ssgEntity* oModelEntity = ssgLoad(szFile);
  ssgRoot*   oModel = new ssgRoot;
  oModel->addKid(oModelEntity);

  glNewList(iListID, GL_COMPILE);
  glPushMatrix();
  glRotatef(-90, 1,0,0);            //ssgRawDraw allows for regular
opengl transforms
  glScalef(0.25f, 0.25f, 0.25f);
  ssgRawDraw(oModel);
  glPopMatrix();
  glEndList();

  delete oModel;
  delete oModelEntity;

  return iListID;
}
void RenderModel(int iListID)
{
  glCallList(iListID);
}
---------------------------------

You are welcome to integrate this code into plib if you wish.  Also, if
you have any suggestions of changes I would be glad to hear them.

Implementation:
-----
ssg.h
-----
void ssgRawDraw ( ssgBranch *root ) ;

class ssgEntity : public ssgBase
{
  ...
  virtual void raw_draw ( bool translucent_objects ) = 0 ;
  ...
}
class ssgLeaf : public ssgEntity
{
  ...
  virtual void raw_draw ( bool translucent_objects ) ;
  ...
}
class ssgBranch : public ssgEntity
{
  ...
  virtual void raw_draw ( bool translucent_objects ) ;
  ...
}
class ssgTransform : public ssgBaseTransform
{
  ...
  virtual void raw_draw ( bool translucent_objects ) ;
  ...
}
-------
ssg.cxx
-------
void ssgRawDraw ( ssgBranch *r )
{
  r->raw_draw(false);
  r->raw_draw(true);
}
-------------
ssgBranch.cxx
-------------
void ssgBranch::raw_draw ( bool translucent_objects )
{
  for ( ssgEntity *e = getKid ( 0 ) ; e != NULL ; e = getNextKid() )
    e -> raw_draw ( translucent_objects ) ;
}
----------------
ssgTransform.cxx
----------------
void ssgTransform::raw_draw ( bool translucent_objects )
{
  glPushMatrix () ;
  glMultMatrixf ( (float *) transform ) ;

  for ( ssgEntity *e = getKid ( 0 ) ; e != NULL ; e = getNextKid() )
    e -> raw_draw ( translucent_objects ) ;

  glPopMatrix () ;
}
-----------
ssgLeaf.cxx
-----------
void ssgLeaf::raw_draw ( bool translucent_objects )
{
  if (isTranslucent() != translucent_objects)
    return;

  if (hasState())
    getState()->force();

  draw_geometry () ;
}
-----------


Thanks for creating a great library =)
Tyler Ohlsen

Re: [Plib-users] STATES

[<m_p...@ya...>]

Ok, but I need to change the state (I need an state selector for this object) and if I make it with an ssgEntity * I cannot do it becouse with the ssgEntity class you cannot acces to the ssgLeaf states without a casting. isn´t it?
 
Thank you.

Steve Baker <sjb...@ai...> wrote:
Manuel Pecero Rodríguez wrote:

> So, in order to add a ssgLeaf to the tree of a Scene I make a 
> ssgVtxTable *dtl; Then I load on it an ac file with the function 
> grssgLoadAC3D(const char *filename, const ssgLoaderOptions *options).

No, no, no! You need something like:

ssgEntity *br = ssgLoad ( filename, options ) ) ;

if ( br == NULL )
/* some kind of error message */ ;

scene -> addKid ( br ) ;

Where: 'scene' is some kind of ssgBranch node - maybe the ssgRoot at
the top of your tree.

---------------------------- Steve Baker -------------------------
HomeEmail: WorkEmail: 
HomePage : http://www.sjbaker.org
Projects : http://plib.sf.net http://tuxaqfh.sf.net
http://tuxkart.sf.net http://prettypoly.sf.net
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V-- PS++ PE- Y-- PGP-- t+ 5 X R+++ tv b++ DI++ D G+ e++ h--(-) r+++ y++++
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---------------------------------

 [input]   [input]   [input] 

Re: [Plib-users] STATES

[Steve B. <sjb...@ai...>]

Manuel Pecero Rodr=EDguez wrote:

> So, in order to add a ssgLeaf to the tree of a Scene I make a=20
> ssgVtxTable *dtl; Then I load on it an ac file with the function=20
> grssgLoadAC3D(const char *filename, const ssgLoaderOptions *options).

No, no, no! You need something like:

   ssgEntity *br =3D ssgLoad ( filename, options ) ) ;

   if ( br =3D=3D NULL )
     /* some kind of error message */ ;

   scene -> addKid ( br ) ;

Where: 'scene' is some kind of ssgBranch node - maybe the ssgRoot at
the top of your tree.

---------------------------- Steve Baker -------------------------
HomeEmail: <sjb...@ai...>    WorkEmail: <sj...@li...>
HomePage : http://www.sjbaker.org
Projects : http://plib.sf.net    http://tuxaqfh.sf.net
            http://tuxkart.sf.net http://prettypoly.sf.net
-----BEGIN GEEK CODE BLOCK-----
GCS d-- s:+ a+ C++++$ UL+++$ P--- L++++$ E--- W+++ N o+ K? w--- !O M-
V-- PS++ PE- Y-- PGP-- t+ 5 X R+++ tv b++ DI++ D G+ e++ h--(-) r+++ y++++=

-----END GEEK CODE BLOCK-----

[Plib-users] STATES

[<m_p...@ya...>]

Hi everybody.
 
I´ve a problem and I dont know how to resolve it. I don´t have a lot of experience with PLIB and I thought that maybe someone had this problem before. 
 
So, in order to add a ssgLeaf to the tree of a Scene I make a ssgVtxTable *dtl; Then I load on it an ac file with the function grssgLoadAC3D(const char *filename, const ssgLoaderOptions *options).
 
Till there is everything ok. I can load the ac file in my scene whith out problem, but if I want to acces to the state of the dtl (It doesn´t mind if I use dtl->getState() or dtl->setState(ssgState*)) my program breaks.
 
My code is something like that:
 
char *acname; 
 ssgVtxTable *dtl= new ssgVtxTable;
 void *hndl = grTrackHandle;
 
dtl= (ssgVtxTable *)grssgLoadAC3D(acname, NULL);  
 /* in acname is the path of the ac file*/
dtl->setState(.....);
 
It compiles and the program runs but it crashes.
 
thank you


		
---------------------------------

 [input]   [input]   [input] 

Re: [Plib-users] Plib as a Model Loader

[Steve B. <sjb...@ai...>]

Tyler Ohlsen wrote:
> I'm looking at using plib as a model loader for a flight simulator type
> application I'm making, but that's all I want plib for.  (I don't want
> to use plib as my scene graph library)

The problem with 3D file loaders is that they have to load the model
into some kind of data structure.  The name for that data structure
is a "Scene Graph".  Hence, loaders for 3D file formats cannot exist
wihout a scene graph.  Since rendering stuff out of that scene graph
is an easily automatable process - and since it makes a lot of sense
to use a C++ class hierarchy to do the work, it follows that the
renderer and the file loader are tightly knitted together.

Tossing out the renderer in order to get the loaders is not generally
a good idea.

> I've played around with the simple scene graph module and I see that
> calling ssgCullAndDraw throws out the existing projection and modelview
> matrices forcing you to use ssg's camera.  I would like to use my own
> camera and not have to use ssg's camera at all.  

SSG lets you set both the modelview and projection matrix directly.

It's hard to imagine what "your own camera" could be that SSG couldn't
already handle.

> Is there a way to call a draw method of an ssgRoot object that does not
> throw out the these matrices and leaves the view culling up to the
> application (it just draws around the current zero point like
> glutSolidTeapot and such)?

No - because SSG needs to know that those matrices are in order to
do field-of-view culling, Range-switched nodes and such.   OK - we
*could* read those matrices back from OpenGL in order to find out
what your camera code set them to - but reading things back from OpenGL
is something to be avoided at all costs.

So it's better for you tell use what you want them to be and let us
send them to OpenGL...that's no different from you sending them to
OpenGL - but this is more efficient.

>  If there doesn't exist such a method, would
> there be an interest for me to create one for you all?

I don't see any conceivable need for that - but if you can come up
with something convincing, we could certainly consider it.

---------------------------- Steve Baker -------------------------
HomeEmail: <sjb...@ai...>    WorkEmail: <sj...@li...>
HomePage : http://www.sjbaker.org
Projects : http://plib.sf.net    http://tuxaqfh.sf.net
            http://tuxkart.sf.net http://prettypoly.sf.net
-----BEGIN GEEK CODE BLOCK-----
GCS d-- s:+ a+ C++++$ UL+++$ P--- L++++$ E--- W+++ N o+ K? w--- !O M-
V-- PS++ PE- Y-- PGP-- t+ 5 X R+++ tv b++ DI++ D G+ e++ h--(-) r+++ y++++
-----END GEEK CODE BLOCK-----

[Plib-users] Plib as a Model Loader

[Tyler O. <Xa...@ho...>]

I'm looking at using plib as a model loader for a flight simulator type
application I'm making, but that's all I want plib for.  (I don't want
to use plib as my scene graph library)

I've played around with the simple scene graph module and I see that
calling ssgCullAndDraw throws out the existing projection and modelview
matrices forcing you to use ssg's camera.  I would like to use my own
camera and not have to use ssg's camera at all.  

Is there a way to call a draw method of an ssgRoot object that does not
throw out the these matrices and leaves the view culling up to the
application (it just draws around the current zero point like
glutSolidTeapot and such)?  If there doesn't exist such a method, would
there be an interest for me to create one for you all?

Thanks,
Tyler

Re: [Plib-users] Buiding Sky using the functions in ssgaSky

[Nick M. <nic...@ds...>]

Michael Wessels wrote:

>I have tried the sky example and it runs well.
>  
>
great !  well if the example works then maybe there is a bug in your code ?

>The difference in my code is, that the function sky->build(...) is called in
>a different file as the function sky->preDraw(() .
>  
>
are you sure the 'sky' objects in both files are pointing to the same 
object (i.e. are the pointers the same) ?

>If I'am using the functions init_graphics and redraw of the example sky in
>my code.Tthe scenery with the sky is rendered then well but in another
>window than my simulation is running.
>
>Where comes the problem from?
>  
>
without seeing your code its difficult to say what is going wrong.

Cheers,
Nick

Re: [Plib-users] Buiding Sky using the functions in ssgaSky

[Michael W. <mic...@ti...>]

Hi Nick,
I have tried the sky example and it runs well.
The difference in my code is, that the function sky->build(...) is called in
a different file as the function sky->preDraw(() .

If I'am using the functions init_graphics and redraw of the example sky in
my code.Tthe scenery with the sky is rendered then well but in another
window than my simulation is running.

Where comes the problem from?

Best regards



----- Original Message ----- 
From: "Nick McEvoy" <nic...@ds...>
To: <pli...@li...>
Sent: Monday, June 28, 2004 6:46 AM
Subject: Re: [Plib-users] Buiding Sky using the functions in ssgaSky


> Michael Wessels wrote:
>
> >Hi all,
> >with the new function build in ssgaSky I tried to create the sky in my
> >simulation.
> >The code was compiled and linked with VC++ 6.2 .
> >But in the execution of
> >sky->preDraw() :
> >  it runs in the following error
> >"Nicht abgefangene Ausnahme in FDS.exe: 0xC0000005: Access Violation"
> >at the function
> >  glDrawArrays ( gltype, 0, num_vertices ) ;
> >in
> >void ssgVtxTable::draw_geometry ()
> >{
> >........
> >........
> >  glDrawArrays ( gltype, 0, num_vertices ) ;
> >........
> >........
> >}
> >The parameter num_vertices has the value 0 .
> >
> >What is going wrong ?
> >
> >
> Weird !  My answer is ... I don't know.  :-(
>
> Have you tried the sky example (/plib/examples/src/ssg/sky/) ?  Does it
> work ?
>
> If the sky example code works ... what are the differences with how you
> use ssgaSky in your project ?
>
> Cheers,
> Nick
>
>
>
> -------------------------------------------------------
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Re: [Plib-users] Buiding Sky using the functions in ssgaSky

[Nick M. <nic...@ds...>]

Michael Wessels wrote:

>Hi all,
>with the new function build in ssgaSky I tried to create the sky in my
>simulation.
>The code was compiled and linked with VC++ 6.2 .
>But in the execution of
>sky->preDraw() :
>  it runs in the following error
>"Nicht abgefangene Ausnahme in FDS.exe: 0xC0000005: Access Violation"
>at the function
>  glDrawArrays ( gltype, 0, num_vertices ) ;
>in
>void ssgVtxTable::draw_geometry ()
>{
>........
>........
>  glDrawArrays ( gltype, 0, num_vertices ) ;
>........
>........
>}
>The parameter num_vertices has the value 0 . 
>
>What is going wrong ?
>  
>
Weird !  My answer is ... I don't know.  :-(

Have you tried the sky example (/plib/examples/src/ssg/sky/) ?  Does it 
work ?

If the sky example code works ... what are the differences with how you 
use ssgaSky in your project ?

Cheers,
Nick

[Plib-users] Buiding Sky using the functions in ssgaSky

[Michael W. <mic...@ti...>]

Hi all,
with the new function build in ssgaSky I tried to create the sky in my
simulation.
The code was compiled and linked with VC++ 6.2 .
But in the execution of
sky->preDraw() :
  it runs in the following error
"Nicht abgefangene Ausnahme in FDS.exe: 0xC0000005: Access Violation"
at the function
  glDrawArrays ( gltype, 0, num_vertices ) ;
in
void ssgVtxTable::draw_geometry ()
{
........
........
  glDrawArrays ( gltype, 0, num_vertices ) ;
........
........
}
The parameter num_vertices has the value 0 . 

What is going wrong ?

Best regards

Michael