Thanks for creating this plugin. This is the ONE-AND-ONLY feature missing in Paint.NET that kept it from being my primary editor of choice for making game textures (normal maps in particular...as noted by my tutorial below).
If I can make a suggestion, please include readme files in your archives. They are very important since they will become detached from their source location (such as this thread).
Including a readme can provide very helpful information as well as keeping credits with the file and your permissions/licensing info too.
Here is a readme file I put together and have with my local copy. Feel free to use.
Name: Alpha Mask Import Plugin
Version: 2.0
Date: 10/15/2009
Author: Illnab1024
Source: http://forums.getpaint.net/index.php?showtopic=1854
Description
===========
This plugin allows you to import an image from a file or the clipboard and make it an alpha mask. If the image has color, it will be converted to greyscale.
The supported image types at the moment is kinda sketchy, but the kicker is it works for stuff copied inside Paint.NET, which is 99% of this plugin's use, anyway.
NOTE: The Effects API cannot handle layer information so the image used must be flat and non-layered.
Installation
============
Copy the .dll file to the "Effects" sub-folder under Paint.NET's installation folder.
Example:
C:\Program Files\Paint.NET\Effects\AlphaMask.dll
Tutorial
========
Let's say we have a color map (texture) and a normal map and we need to get a slightly darker version of the color map copied into the alpha channel of the normal map so we can save it to DDS (DXT5+Mipmap) format.
1. Open both files in Paint.NET (you should see two thumbnail images in the top-right corner)
2. Select the color map image, click Adjustments --> Brightness and reduce the brightness by -20 and click OK
3. Press CTRL + A to select the entire image and press CTRL + C to copy it into memory.
4. Select the normal map image, click Effects --> Alpha Mask and make sure "paste from clipboard" is checked and click OK
5. Your normal map now looks partially transparent which means the alpha mask worked. Save your image in the native .pdn format so you can edit it later if necessary.
6. Now save your image to DDS format and choose DXT5 format and make sure "Generate Mip Maps" is checked and click Save.
Credits
=======
Clipboard idea courtesy BoltBait.
The file import is based from pleska's Photo Flood Fill Plugin.
Thanks,
LHammonds