OSG Exporter - Texture seams somehow have alpha

[shivanangel]

Try moving your UVs a very small amount away from the corners to quick fix the problem.
Also, did you make the original texture in Photoshop and resize the image?
Many times, the edges of images that are not flattened first are given a feathering at the edges, which can result in poor seams at the corners. Are you starting with a different format than jpeg, such as PNG or TGA which has an alpha channel?

Do you get the same problem when you change your compression type from DX to no compression? It looks at first glance like a compression problem from the image...

[JvdBosch]

Originally Posted by shivanangel

Try moving your UVs a very small amount away from the corners to quick fix the problem.

There are no corners in the model. It's one big polygon. Within the polygon this happens.

Originally Posted by shivanangel

Also, did you make the original texture in Photoshop and resize the image?
Many times, the edges of images that are not flattened first are given a feathering at the edges, which can result in poor seams at the corners. Are you starting with a different format than jpeg, such as PNG or TGA which has an alpha channel?

Do you get the same problem when you change your compression type from DX to no compression? It looks at first glance like a compression problem from the image...

I used DXT1, which only has 1-bit alpha. The seams are clearly more than 1-bit alpha. The texture files are flat jpg/bmp files, with no alpha attached. This model worked fine in 3DS Max Design 2011...

[shivanangel]

Originally Posted by JvdBosch

There are no corners in the model. It's one big polygon. Within the polygon this happens.

So it is your texture that is causing this issue and it wrapping from one polygon to the next.

I used DXT1, which only has 1-bit alpha. The seams are clearly more than 1-bit alpha. The texture files are flat jpg/bmp files, with no alpha attached. This model worked fine in 3DS Max Design 2011...

I've noticed exporting issues with some image files when exporting from the native format to whatever techniques are used in 3D Studio Max to convert them to other file formats. Did you try this with no compression and see if you get the same result?
Just because it works in 3DS Max does not mean it will work outside of the application. Especially when you consider mipmapping and the potential for textures to be resampled during the export and import process.

[JvdBosch]

Originally Posted by shivanangel

I've noticed exporting issues with some image files when exporting from the native format to whatever techniques are used in 3D Studio Max to convert them to other file formats. Did you try this with no compression and see if you get the same result?
Just because it works in 3DS Max does not mean it will work outside of the application. Especially when you consider mipmapping and the potential for textures to be resampled during the export and import process.

Like I said, the exact same model with the same textures exported fine in 3DSMax 2011. Something has changed on either 3DSMax 2013, the exporter or both. I'll try to reproduce the issue with a simple max file, so the experts at WV can take a look.

It looks like the exporter is doing something weird at the edges of the texture images. I had something similar with tree textures, face mapped to a square polygon. At the edges of the polygon the transparency of the texture disappeared, so it looked like the trees were inside a box... So exactly the other way around than the wall, where a transparency appears at the edges of the texture.

[JvdBosch]

Here's an example to download.

It is just one tree, made with two crossed polygons and a simple material. When exporting a line appears at the edges of the texture. I believe this is the same problem as with the wall. Some weird alpha thing happens at the edges of the texture. In my opinion it has nothing to do with the polygons, but everything wih the textures.



Can someone take a look at this problem?

[Veleno]

With the brick wall texture, what format are you using? The transparency seems texture-based, so it is most likely something wrong with the texture itself. Bring the image in photoshop and check for an alpha channel. if there is one, delete it and export again.

If this is in a baked scene, edit the image output settings to disable the automatic creation of alpha channels in baked textures.

The problem wiith the tree can be solved by using multi-sampled alpha. This kind of artifact usually happens when one transparent object intersects with another.

 
import viz

viz.setMultiSample(4) 
#higher values increase quality but decrease framerate. 
#usually set between 2 and 16

viz.go()

tranModel = viz.add('model.IVE') #add a model, call it tranModel

GL_SAMPLE_ALPHA_TO_COVERAGE_ARB = 0x809E
transModel.disable(viz.BLEND)
transModel.enable(GL_SAMPLE_ALPHA_TO_COVERAGE_ARB)

viz.clearcolor(viz.GRAY)

[Veleno]

The above code has a typo - lines 12 and 13 say "transModel" instead of "tranModel", so be sure to fix that if you try it out.