[visionegg] Re: Texture artifacts

Dear Gabriel,

The most likely cause is how OpenGL stretches texel data to fill a textured patch. This seems to vary slightly from card to card, and testing these differences and trying to make the Vision Egg perform acceptably on all cards is why test/conform.py exists. I suggest trying various texture_wrap_s & texture_wrap_t settings in subclasses of TextureStimulusBaseClass. Also, you may try to give texel data that is exactly a power of 2 in each dimension (e.g. 512x512). I hope this helps.

Cheers!
Andrew

On Jun 13, 2005, at 9:26 AM, Gabriel Nevarez wrote:

Hello all,

This is very likely a simple fix:

When loading textures and superimposing them atop other stimuli, I often get
visual artifacts around the edges of the texture, likely due to OpenGL
texture manipulations. I have included a jpeg image of a screen capture
with one such texture artifact (in this case, the top and right edges are
shown as grey bars, where the texture meets the background).

I have tried different internal_format settings to no avail. I have seen
this problem before in previous studies and found that I had to actually
draw my stimuli using the Python Imaging Library.

Anybody know a workaround for this?

Cheers,

-=Gabriel Nevarez
Research Programmer
Psychology Department
Cardiff University
http://www.cf.ac.uk/psych

<artifacts.JPG> 


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