Norris's picture

very strange artifacts

Hi !
I have an application that works fine on my computer, but when a friend try this, He have a very strange result. I have never seen this on my 2 computer (1 old xp and a brand new seven). What could cause this ? shader ? MSAA ?
I think it's an OpenGL parameter, but which one ...

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Norris's picture

Hi !
Nobody have experienced this kind of artifact ?
I really suspect the shader, but this is a very simple one that we can found on many tutorials.

c2woody's picture

If in doubt blame it on the Intel graphics chip.....

Norris's picture

Hi c2woody
Thanks for your help.
Are Intel chipsets well known to have a bad support of OpenGL in general ? or do you think it's a shader problem ?
I have read that sometimes, it's just a problem with one function, but we can certainly find another one that is well supported ... is it known especially for Intel chipsets ?
This is from a portable computer.

I think it won't be easy to find what cause this without someone who had the same problem.

c2woody's picture

Sorry no idea what that specific problem might be, I've experienced several different problems with older (pre-HD) intel graphics chipsets but was able to "avoid" these lately.

Be sure to add a lot of error checking to the OpenGL functions (including a debug-enabled OpenTK dll) and check your application with tools like gDEBugger. Please keep us updated if you figure something out!

Norris's picture

Hi ! and good year for all ;D

My friend sent me a commercial picture of this portable computer and I really don't know what to think. For the graphic card, this capture say:

AMD Radeon HD 6470M 1Go

But on the screen capture of the appli he sent to me (see above), we can see "Intel" chipset !?!?
I'm not a great programmer and I don't really know how to debug with OpenTK in debug mode. I have downloaded gDEBugger but haven't tried yet. My friend must look himself ....

Is it possible that the appli doesn't use the graphic card but only the chipset of the motherboard ?

Tell me if I'm wrong ... AMD & ATI are the same now ? (I know that Radeon was from ATI before but was never been from Intel)

c2woody's picture
Quote:

Is it possible that the appli doesn't use the graphic card but only the chipset of the motherboard ?

Yes looks like something like that, I'm unfamiliar with AMD (former ATI) mobile graphics chips, but you should try to check if the drivers are correctly installed, and if the device manager lists the radeon mobile card.

Quote:

I don't really know how to debug with OpenTK in debug mode.

Compile OpenTK from sources and use the Debug profile. Running your application using a debug OpenTK version may give further hits about what's happening.

If you can get your hands on that laptop for a while try to check the OpenTK examples, maybe the shader ones already exhibit problems, or some other features behave strange so you have something to work on.

Norris's picture

"you should try to check if the drivers are correctly installed, and if the device manager lists the radeon mobile card."
Yes, that's what I say to my friend. I haven't access to this laptop, so I can't do many things. I wait an answer from him.

Thanks for the basic step to use OpenTK in debug mode! since I program with OpenTK, I have always found myself my strange coding bugs, but for my knowledge, i must learn how to use this ... the "good" time is comming ...
Thanks for your help. I will come back if I have new informations.

blackbee's picture

it looks familiar to the problem I had with ATI Radeon 5XXX on my laptop. It looked like this:
http://www.youtube.com/watch?v=Pvp1ttDEEYY
I've solved it by turning off PowerPlay (power consumption saver) in driver settings.

Norris's picture

Hi blackbee and many thanks for your report !
as you said, this looks very familiar ! I will ask to my friend to try this.
But I don't really understand the correlation between graphics and power saver options. I'm not an expert, and you're certainly better than me. If this solve the problem, do you agree my friend will have problem on many OpenGL based games ?