Transparency Problem

I ran into an issue while working on my Balrog, and I can see no way around it. I thought I would see if someone else could help me.
I wanted a wing with rips and tears in the edges. I decided to simulate that by creating a perfect wing mesh, and adding rips as an alpha transparency. I set it up nicely, I had wonderful rips, and I set the wing to Ray Transparency. However, I also wanted a cloud of dust to follow the beast. This I setup with particles set to Halo. However, when I added the two together, I ran into my problem. While the particles in front of the wing alpha were rendered, anything behind it was not visible.

An example of the issue.


Here is a blend file demonstrating my problem.
wingtrans.blend (443 KB)
Is there a way around or to fix this problem?

Thax

I don’t know if it suits your purpose, but using Z Transparency for the wing will fix it.

Halo is going to give you problems. Try using billboard instead. Supply a small radial gradient with an alpha as the map source for the billboard.

Attachments


For your wing, use Z transarency instead of raytracing. In the Map To panel, use either Alpha with Multiply as texture blending mode, or Invert Alpha (the Alpha button gecomes yellow) and Substract as texture blending mode.Then, adjust your transparency with the Alpha factor in the material panel.

Remember that the texture blending mode for an alpha layer is almost always Multiply or Substract. Using Mix like in your example can’t make “holes” in your texture.

Use Ray transparency only in case you gate a visible border around a billboard, that you have difficulties to avoid. It is time consuming at rendering and isn’t always necessary.

I’m not quite sure what you mean by that?

See for example
http://en.wikibooks.org/wiki/Blender_3D:_Noob_to_Pro/Using_a_texture_to_make_a_material_partially_transparent

I have not yet found a reason to use Multiply or Subtract for an Alpha texture.

I have not yet found a reason to use Multiply or Subtract for an Alpha texture.

Well, for me The good reason if that I have never been able to get it work with Mix as blending method !o)

instead, it works fine with Multiply and Substract.

It is easyly understandable as Black value is 0 and white value is 1.

When you multiply an alpha value by 0, you get full transparency.
When you multiply an alpha value by 1, you don’t modify the opacity.
With values in-between (grey scale), you get a variable transparency.

With substract : substract 0 doesn’t affect the alpha value. Substract 1 gives alpha =0= full transparency.

With values in-between (grey scale), you get a variable transparency.

@ ROUBAL

In my (small) experience, i also noticed that Substract does it fine. Till now, i had no reason yet to use Multiply for Alphaing something… but i’ll try that out soon.