i´ve made a tiny module that can be used to “echo” the current rendered picture. i was searching for this functionality for some time…

here it is (:

but with this module there comes a question. everytime i trigger the “insert” bang (insert DX9 texture into Queue (Texture), one frame) the backupped image moves one pixel (?) left and down. Since i did not apply any transformations i´m a bit suspicious. Some directX conventions i don´t know?

Thx in advance.


dx9echo.zip (3.0 kB)

with the pixel movement:

most graphic drivers offer the possibility to adjust this, however the name for this setting is always slightly different. I don’t know exactly why this is a variable, but is about how pixel and texel correlate to each other…
sometimes it is a slider, sometimes a checkbox.
would be good to make a list of the different names for this setting in the different graphic drivers right here…

I think I am fighting with the same “pixel movement” problem since a few days.

I am trying to use a pixel shader (my first one) in a loop and was wondering that the result alway is slowly “smearing” to the lower right corner.
Could this be the same problem ?

I am using a NVIDIA 6600GT - does anybody know how the setting is named here ? I can´t find the right slider or checkbox.


on my ati-driver it is a checkbox:
“pixelzentrum wechseln”:

hard to find under the 3d-tab: the “compatibility” button.

anyway, it should be considered as a bug when it shifts the texture with an unmodified driver setting - iirc the driver settings are just for tweaking apps written against the wrong specs.

the same issue always occurrs if someone wants to do pixel precise mapping of textures. most of the time it is needed to shift them half a pixel to have them properly mapped.

tested the shader/patch on a system with an ATI 9800.

With the “after driver install default settings” the image was smearing to lower right edge of the renderer exactly like with the nvidia card.

After setting “pixel-Zentrum wechseln” to “aktiviert” everything looks fine and stable.

In the nvidia driver I did not find any checkbox or slider to solve this problem (first plus ever ever I found in an ati driver !?) Does anybody out there know how to change this setting for nvidia cards ?

I think I want to agree with Sebastian that this effect should be called “a bug” … something that could be changed within the next release ?


do i get you guys right that the graphics cards themselves build up this movement ? as result of the pixel centering algorithm?

nothing i can do on a nvidia system then…

i’m quite positive that nvidia drivers have a similar option. as soon as i get my fingers on an nvidia card i’ll let you know.