Here I will explain how to make alpha layers in Paintshop Pro, for use in Second Life. I am working here on a texture for a simple picket fence to apply to a prim, but the technique is identical for clothing layers also.
First I have drawn a very simple picket fence texture. As you can see it has a white background, which is no good: we want to be able to see through the slats.
Next, I duplicate the layer as shown (this is because you cannot make part of the background layer transparent, you can only put transparency in the upper layers).
Hide the background layer by clicking on the eye to make it invisible.
Make sure you are working only on the upper layer. Use the Magic Wand tool (shown on the left) to select all the white parts and delete them. This shows the transparent “checkerboard” pattern behind. Any part of the image showing this checkerboard will be transparent when uploaded into Second Life.
On the Layers menu, click “New Mask Layer” and then “from Image”.
A dialog box will pop up. Leave everything as it is, and click OK.
Make sure the Mask layer is selected (see arrow on the right). Then click Layers menu, “Load/Save Mask”, then “Save Mask to Apha Channel”.
Another dialog box will pop up showing your fence in black and white. Black parts will be totally transparent. White parts will be totally solid. If you have areas of partial transparency these will be various shades of grey (as you might have for smoke, sheer fabric etc – however there are no such areas in this simple texture).
Save the image now as a PNG file. DO NOT MAKE THE BACKGROUND LAYER VISIBLE AGAIN! You will get a dialog box warning you that you can only save one alpha channel. Click OK on this: there is only one here anyway. Give your texture a file name that you will remember.
Now go into Second Life and upload your texture (Build menu, or Ctrl-U). I am showing Firestorm here, and I’m using the free temporary upload feature but if you are uploading a texture you want to keep, you’ll use the ordinary pay-for-upload option.
You will see on the texture preview window that it is showing transparent between the slats instead of white. Click “Upload” to confirm and click “OK” when the dialog pops up to say that it’s complete.
Rez your prim, stretch it out to the desired shape and apply the texture to it.
As you can see, the areas between the slats are transparent, so you can see the pretty horsie. 🙂