Alpha channel question for the experts

Is it possible to have a 'doughnut shape' alpha channel?

I want to make a Xmas wreath and have only the wreath show.

Any suggestions?

tia

Absolutely. The way it works is any part of the canvas that is black on the alpha channel will be transparent in the texture. Any part that's white will be opaque. Anything gray will be in between (translucent), the darker the gray the more transparent, the lighter the more opaque.

Your alpha channel could look like a donut, a square, a starfield, a polar bear blowing his nose in a snowstorm, whatever you want. You can paint on it directly, or you can use any of the methods you're already familiar with from your other thread to auto-generate it from selection.

For example, if your wreath looks like this:



Then your alpha channel should look roughly like this:



The end result will be the wreath will be opaque (since the part of the canvas that contains it is white on the alpha channel) and the background will be transparent (since that part is black on the alpha channel).




Note: I don't have copyright on the wreath image I linked, and neither do you, so don't use that one. Use your own.

Once again, thank you.

Is there anything you DON'T know about alpha channels? lol

You're welcome, Tron.


Hehe, I'm not sure exactly how I became the alpha channel guru, but I guess someone had to do it. You should have seen what this place looked like before that guide went up. At least every third question on this board was "what's an alpha channel?" or "how come my transparency doesn't work?", or something along those lines.

Alpha channels are very simple and very powerful, but they're certainly not intuitive when people are new to them. It takes a little bit for it to click. It's a visual-mathematical way of thinking about imagery that most people aren't used to at first.

Anyway, to answer your question, yes, there are things I don't know about alpha channels. I've never been able to train one to roll over, to sit, or to play dead.

I'm willing to bet that's only because you didn't WANT to.

Off-topic, I know, but...


Thanks for the laugh !

Hi, I'm new to SL and I'm trying to make some decent hair for myself. I want to upload a hair texture that has a "fringe" edge to it. I've read that I should save in TGA format. Do I need to upload a seperate alpha channel or is there an alpha layer or something? I have PSElements. But I've never made TGA's. Or I could just use the hair texture already in the game if I could figure out how to turn it 90degrees on the object. I'll be pretty grateful for any help and advise.

Read the stucky topic at the top of the Design and Textures forum on how to use alpha channels.

Short answer, you'll need a 32-bit .tga file to import, so it can have an alpha channel that masks off the fringe of the hair.

I can't recall off-hand of Photoshop Elements is adequate for this, or if it is beyond the reach of that app. I have a copy that I rarely use. (Came with my graphics tablet) I checked, and I have uninstalled it, since I have the full version of Photoshop.

In the full photoshop, you can right click a layer in the Layers pallete and choose "Select Layer Transparency", then go to the Channels pallette and use that data to make an alpha channel. Saving as 32-bit TGA will retain that data when you import the TGA file to SL.

No Chosen, the questions were, "What's an alpha layer.

For you newer folks, Chosen set us all straight on that one. Reading what Chosen writes is like taking a college course on color and graphics.

Jen

Thank you. I am so new and clueless that I hadn't even found that yet. But I did manage to get the texture I wanted. I made it in PSP7 just with layers and transparency where I wanted it, saved it as a .psd file then opened it up in The Gimp and exported it as a .tga file. Gimp knew how to do it even though I didn't. Thanks again for answering.