Single object, varying transparencies

How can I have an object that's image is partially, as in a portion, say the bottom third 70% transparent. The middle third 30% and the top 90%?


Or am I going to have to use compleltey separate objects, pieced together?

 

Anybody?

 

Simply add an alpha channel to the uv?

 

Use a transparent shader of some kind and have the alpha channel in the texture. Black is 0% visible and white is 100% visible, shades of gray are the transparency levels.

 

Right,
But can I have a section of the mesh, material be more transparent than another section? Or do I need separate objects for that?

 

I don't understand, the material covers your mesh, if a section of the material is transparent, than a section of the mesh will be transparent.

 

or just use a material that has varying levels of transparency? What am I missing here?

 

ok, I was not aware you could do that. Can you point me in the right direction?

Also, just of note, I am currently using a material with only 2 vertices, that should probably be changed? Also, can I for instance make the transparency levels different for a full circumference around the edges of the plane? Then repeat that again closer to the center?


Thanks


edit: @ superpig. different materials method is best?

 

If this is just for a plane and you're asking about varying levels of transparency then you need to do some basic research on alpha blended transparency. If you figured out how to make your character cut out with a transparent background then you can figure this one out too, it's not that tricky.

 

I understand how to use transparency via shaders as well as using alpha to adjust. But if you read the original post you would know what I mean.

Thanks.

 

Yes, I read your post and I'm saying you need to learn how to create alpha channels for your textures with varying levels of transparency.

 

What I am asking is do I need multiple materials for this? Or can multiple alpha adjustments be made on the same material at the same time on the same object?

 

Alpha channels are 8-bit channels with 256 levels. So no, you do not need multiple materials for varying levels of transparency on a single mesh.

Superpig was possibly referring to sorting issues, but that doesn't apply to your question when dealing with single planes being used as billboards.

If you're talking about changing these values dynamically at runtime, then you either need to split it up into multiple materials, use a shader that takes vertex colors into account and dynamically change the vertex colors on the mesh, or split the alpha channel from the diffuse texture in the shader and feed the material different alpha channel textures at runtime (or use a texture sheet and offset the coordinates to map to different sections of the alpha texture).

 

Ok great thank you.

I looked up "alpha blended transparency" but nothing lept out. I think this may be a little beyond me at the moment. As I have not touched UV adjustment or anything. I know how to adjust a single level alpha, but am failing to grasp how an object could have more than 1 alpha.

You say an Alpha has 8 channels so I looked up this..
http://docs.unity3d.com/Documentation/ScriptReference/30_search.html?q=alpha+channel


Sorry for not researching more, but I am out the door for a bit.
Thanks! Your help is appreciated.

 

You only need one alpha channel



Like this would provide every level of transparency needed for the image.

 

I am sorry, I just dont follow.

How can a single material with alpha set to x, have another area set to != 12?


Do you understand that I have an image, lets just say it takes up the entire mesh, material. So there is zero transparency. Now, I want the bottom third to be 50% transparent and the top half to be fully opaque.

How do I do this|?

 

Do a search for creating alpha channels in Photoshop (or whatever image editing app you use).

 

In photoshop click the channels tab in the bottom right of the application (it's next to layers) there is a small button below called create alpha channel or something, click it and it makes an alpha channel, there you put the grey scale image that controls the transparency. Such as:



For what you asked specifically you would want the top to be all white (opaque) and the bottom grey.

 

Oh, so how you import from photoshop plays a roll! Great. I had just been importing solid png fils.

Thanks you!

 

You should be fine now.