Hi Oliver,
Oliver Kutter wrote:
> Hi all,
>
> I want to create some points in a geometry. OK, they are perhaps more
> than "some" points, they are exaktly 2048x2048 points, which are over 4
> Million points in one geometry. The points are particles and until now I
> was calculating their positions in an fbo texture with a shader. That
> all works fine with about 1 million particles, where 1024x1024 is the
> size of the image and the fbo texture which is the render target. So
> 2048x2048 is the next possible size for power-of-2 textures. With these
> sizes the power-of-2 textures have the best performance.
Does it have to be one texture, or can you split it up into a few, like 2 or 4?
Do they have to be square? Otherwise you could try 1kx2k as a compromise.
> Now, there are some problems with 4 million points:
>
> I have 2 errors on 2 different computers.
>
> The first computer with 2GB RAM has a Geforce 7600GT. The error is that
> the Image class tells me, that it is not possible to allocate 64MB
> memory, which is the texture size 2048x2048 with 32bit float RGBA values.
That sounds like a straightforward out of memory error from the system, there
is
not really much we can do about it. It's a little surprising, but I guess it
depends on what else is in your program. You can try to increase the swap space
and see what the process size limit on the system is.
> The second computer with 4GB RAM is much faster with a 8600GTX. It tells
> me the following error:
> Geometry::handleGL: couldn't create display list (out of memory)
> skipping geometry ...
You can try to use VBOs instead of DLists, those might use less memory. Or you
can go back to standard VertexArrys which don't use gxf memmory, but
performance
will suffer.
> Does someone have any ideas about this?
> I know that I'm working at the limits of OpenSG and graphics hardware,
> but perhaps there's someone, who can help me.
Hope it helps
Dirk
P.S.: I'd be very curious what you're doing with it. Care to put some pictures
in the Gallery?
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