Hi Shawn,
The application is specifically a viewer for these datasets and, while
in normal operation the user would be expected to reduce the detail
level (and so the number of points) when viewing very large files, one
of the requirements is to have the facility to view large files in full
detail. Applying transformations globally and moving the points away
from the origin also cannot work because OpenGL uses single precision
floating point, which cannot handle the need for having coordinates
that can express, with precision, values such as 20000.345, so I
currently place the points around the origin, their coordinates
subtracted by offsets that change each time. Also, I have been using
GTK because the program has quite a few functions and it allows me
easily to control widgets, multiple resizeable windows and a few other
things. Performance related to the CPU, RAM or the GPU is not the
problem, the problem is only the slow speed of HDD I/O, which I want to
reduce the use of by drawing the points only when they change, not when
something above them changes to uncover some of them.
So, given that, I think my only option (apart from my hastily
implemented method that draws certain things with GTK above the OpenGL
parts (not ideal) or the other possibility of mainipulating the front
and back buffers, which seems a little complicated) is to use overlays,
which my hardware can handle. Given that the function
Gdk::GL::Config::get_layer_plane() exists, it would seem that gtkglext
has the functionality to allow the use of layers, perhaps by creating
different contexts for each layer, but I cannot work out how to do it.
How does it work?
On 10/02/10 18:08, Shawn Bakhtiar wrote:
hhmmmm....
That is a very VERY large data set. 1 million points! And the user
needs to interact with all these points? Have you tried coming up with
a clipping volume application side, which would reduce the number of
points to render?
If the vectors are static around the origin, then the compilation
should work, since all the rotation and translation would be applied
globally . If the vectors are moving independently and change in
respect to each other, then you are right compiling will not help.
Compiling si good for rigid structures NOT fluid, as you have to
recompile every time you make changes to the model.
I guess my next question would be why, this intensive an application,
would you use a GUI anyway? For these many vectors you need LOTS of
memory, and some power full CPU/GPU combination (optimization at the
GPU level, really comes from drawing triangular surfaces, as they have
hardware matrix calculators build in, more importantly the line cal is
done hardware side). And why consume all that memory, with a windowing
system. IMHO, all that many points are no good, unless it is full
screen, so drop the gtkmm re-write in C, using the direct OpenGL
libraries using platform specific.
I think you will see performance drastically improve ( -GUI).
just my MHO, hope it helps.
Shawn
Date: Wed, 10 Feb 2010 10:59:10 +0000
From: harg pml ac uk
To: gtkglext-list gnome org
Subject: Re: [GtkGLExt] Is it possible to use overlays with gtkglextmm?
Hi Shawn,
Unfortunately, I do not think that will work for me. I am dealing with
something of the order of 100 million points or more, and I tried to
use display lists previously. If I remember correctly, the reason I
stopped using them was because they used up a huge amount of my memory
when created (I do not know whether they always do this or if it was
some sort of excess after the graphics card memory had been filled).
That was a couple of months ago. Since then the program has been
changed so that now the points move (change vectors, I presume) around
the origin as, before, there were precision problems relating to
OpenGL's conversion of doubles to floats. As it is, the program is
pretty quick in most situations except when we are using the hard drive
to store data and caching it (we do this because the data can, on
occasions, be 10 GB or more), and I do not see how display lists can be
used with caching.
For that reason I want the facility to write to different "layers"
independently, such as the overlay facility, if it possible. Currently
I am attempting to fiddle with the front and back buffers, copying from
one to the other, but I would rather try the overlays (which my
graphics card says it can handle) which I believe would be easier to
understand and maintain. So, can I do this in gtkglextmm, and how? As I
said, Gdk::GL::Config::get_layer_plane() appears to return the number
of a layer, but I do not know what to do with it. Do I somehow create a
new context for each layer?
Regards,
Haraldur
On 10/02/10 01:46, Shawn Bakhtiar wrote:
hhmmmm...
Have you tried to compile the data points for the model (if they do not
change vectors)
somthing like this (from the log example):
/* Forward "G". */
glNewList (LOGO_G_FORWARD, GL_COMPILE);
glDisable (GL_CULL_FACE);
glMaterialfv (GL_FRONT, GL_AMBIENT_AND_DIFFUSE, mat_blue);
logo_draw_g_plane (); /* My user function that calls the actual gl*
to draw */
glEnable (GL_CULL_FACE);
glMaterialfv (GL_FRONT, GL_AMBIENT_AND_DIFFUSE, mat_black);
logo_draw_i (); /* My user function that calls the actual gl* to
draw */
glEndList ();
Hope this helps,
Shawn
> Date: Tue, 9 Feb 2010 17:15:24 +0000
> From: harg pml ac uk
> To: gtkglext-list gnome org
> Subject: [GtkGLExt] Is it possible to use overlays with gtkglextmm?
>
> Greetings,
>
> I have been writing, as my first significant project using OpenGL,
a GUI
> using gtkglextmm for viewing large datasets as a cloud of points.
I have
> some measuring tools that are currently rendered by drawing some
of the
> points and then the line or box of the tool while the user is
dragging
> the cursor. This works well with small datasets but gets sluggish
with
> the larger ones, particularly the ones that require caching. I
would
> like to use overlays as a conceptually and practically simple (I
hope)
> way of drawing the rulers (and so on) without having to redraw the
> points each time.
>
> How do I do this while using gtkglextmm? I found the method
> Gdk::GL::Config::get_layer_plane() but no other obvious things in
the
> documentation. Looking at an example using WGL, it appears I need
to
> create an "layer context" for the overlay, but I do not see how to
do
> that in gtkglextmm. Does it work in a similar way and, if so, how?
>
> Thanks in advance,
>
> Haraldur
>
>
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Registered Office:
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The Hoe
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Website: www.pml.ac.uk
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registered in England & Wales
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PML is a member of the Plymouth Marine
Sciences Partnership
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personal views which are not the views of Plymouth Marine Laboratory
unless specifically stated.
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communications are not secure and may contain viruses. Plymouth Marine
Laboratory accepts no liability for any loss or damage which may be
caused by viruses.
Plymouth Marine Laboratory
Registered Office:
Prospect Place
The Hoe
Plymouth PL1 3DH
Website: www.pml.ac.uk
Registered Charity No. 1091222
PML is a company limited by guarantee
registered in England & Wales
company number 4178503
PML is a member of the Plymouth Marine Sciences Partnership
Website: www.pmsp.org.uk
Please think before you print.
This e-mail, its content and any file attachments are confidential.
If you have received this e-mail in error please do not copy, disclose it to any third party or use the contents or attachments in any way. Please notify the sender by replying to this e-mail or e-mail forinfo pml ac uk and then delete the email without making any copies or using it in any other way.
The content of this message may contain personal views which are not the views of Plymouth Marine Laboratory unless specifically stated.
You are reminded that e-mail communications are not secure and may contain viruses. Plymouth Marine Laboratory accepts no liability for any loss or damage which may be caused by viruses.
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