Yeah, using openGL Points to draw 2D images will probably be pretty slow. However, if you don't need to change your points every frame, a display list might improve the speed quite a bit (you could still transform the points as a whole). Also, you could try the SDL bindings for haskell: http://hackage.haskell.org/package/SDL SDL is better suited for 2D drawing (IMHO). http://www.libsdl.org/ - Job On Thu, Jul 29, 2010 at 6:51 AM, Vo Minh Thu wrote:

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I'm having an unusual problem with OpenGL. To be honest I probably shouldn't be using OpenGL for this, as I'm just doing 2D and only drawing Points, but I don't know about any other display packages, so I'm making due. If this is a problem because of OpenGL however, then I'll have to learn another package. The problem is speed. I have a list of points representing the color of 800x600 pixels. All I'm trying to do is display the pixels on

...

screen. I use the following:

renderPrimitive Points $ mapM_ display list flush where display [] = return () display ((x,y,i):n) = do color $ Color3 i i i vertex $ Vertex2 x y display n

But, for some reason this takes FOREVER. I don't know how to use debugging hooks yet without an IDE -- and I don't use an IDE -- but I used a cleverly placed putStrLn to see that it was actually working, just really really slowly. Is there a solution to this speed problem or should I use a

2010/7/29 Eitan Goldshtrom : the package

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that's more suited to 2D applications like this? Also, if I should use another package, are there any suggestions for which to use? Thanks for any help.

Hi,

Although you can use Vertex* to put a single Point on the screen, it is not meant to be used as some kind of setPixel function.

If your goal is simply to set pixels' value of a raster, you can still use OpenGL but should use a single textured quad (and thus manipulate the texture's pixels).

There other possibilities to deal with raster graphics: - Use gtk; i.e. something like http://hackage.haskell.org/package/AC-EasyRaster-GTK - Output the data in some image format (if you want to do it yourself, the most simple is PPM) - Use X11 directly (if you're on unix) - ...

HTH, Thu _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

Vo Minh Thu schrieb:

There other possibilities to deal with raster graphics: - Use gtk; i.e. something like http://hackage.haskell.org/package/AC-EasyRaster-GTK - Output the data in some image format (if you want to do it yourself, the most simple is PPM) - Use X11 directly (if you're on unix) - ...

or good old HGL: http://hackage.haskell.org/package/HGL

On Fri, 30 Jul 2010, Eitan Goldshtrom wrote:

HGL actually looks like EXACTLY what I need. I only need to set pixels, which looks like just what HGL would be good at. Only problem is that I can't find a single tutorial for HGL. Does anyone know or any, or where I could find one?

I found the Haddock documentation enough for what I tried. Maybe my example can help you: http://hackage.haskell.org/package/hgl-example

On 2010-07-29 11:30 -0600, Luke Palmer wrote:

If you are trying to redraw in realtime, eg. 30 FPS or so, I don't think you're going to be able to. There is just not enough GPU bandwidth (and probably not enough CPU).

Updating an 800x600 texture at 30fps on a somewhat modern system is absolutely *not* a problem. -- Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)

On a modern PC, this is no problem at all. We are actually doing this with a 1920 x 1080 x 32-bit bitmap, at 60 FPS, on a 2-year old PC You can easily test your GPU <-> CPU bandwidth using this tool: http://sourceforge.net/projects/gpubench On Fri, Sep 17, 2010 at 7:53 PM, Lie Ryan wrote:

On 07/30/10 03:37, Nick Bowler wrote:

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On 2010-07-29 11:30 -0600, Luke Palmer wrote:

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If you are trying to redraw in realtime, eg. 30 FPS or so, I don't think you're going to be able to. There is just not enough GPU bandwidth (and probably not enough CPU).

Updating an 800x600 texture at 30fps on a somewhat modern system is absolutely *not* a problem.

It depends. Updating 800x600 screen at 24-bit color 30 times per second requires 800*600*24*30 = 345600000 bytes/s = 329 MB/s which is larger than the size of typical Video Memory, and the first version of PCI Express (introduced 2003) is only 250 MB/s/lane.

While the bandwidth and Video Memory size is sufficient to transfer 329MB/s, it is quite near to the limit, especially if you have another programs running, which may cause some resource contention or if you used some memory-heavy techniques like double buffering.

You're probably quite safe if you have PCI Express version 2, have over 1GB RAM, and a good Video Card. You're probably quite screwed if your VGA uses a Shared Memory Architecture (i.e. it uses RAM for video memory, this easily causes resource contention).

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On Friday September 17 2010 19.53.01, Lie Ryan wrote:

It depends. Updating 800x600 screen at 24-bit color 30 times per second requires 800*600*24*30 = 345600000 bytes/s = 329 MB/s which is larger

Shouldn't that be bits/s, or 800*600*3*30 = 41 MB/s? Mats Klingberg

On 2010-09-18 13:57 +1000, Lie Ryan wrote:

On 09/18/10 07:49, Mats Klingberg wrote:

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On Friday September 17 2010 19.53.01, Lie Ryan wrote:

...

It depends. Updating 800x600 screen at 24-bit color 30 times per second requires 800*600*24*30 = 345600000 bytes/s = 329 MB/s which is larger

Shouldn't that be bits/s, or 800*600*3*30 = 41 MB/s?

yep, blame that on lack of sleep, I guess...

Nevertheless, 4x AGP (circa 2000) can easily sustain the significantly exaggerated rate of 329 MB/s. -- Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)