Movie Brush using region fill as brush pen mode.
The trick to get a movie source brush to work like this with region fill as brush pen mode is to set the Brush Option in the Region as Brush Mode control panel to Alpha Only. You then use a Source Brush Alpha Brush Type. What these 2 control settings do is to build an alpha mask for the source brush based on the generated region and use that alpha mask as the brush shape. You can then set Fill From in the Paint Fill Setup control panel to Brush Image. This will fill the shape generated by region fill as brush pen mode with the individual frames in the movie source brush.
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Alpha is a fancy word for transparency. Under File > Preferences > Layer Preferences, make sure that the "Default Save Output Alpha" is set to "Layer Alpha", and that "Paint Alpha Fill Status" is set to "On". If you are making movies, in the movie compression preferences, make sure your compression is set to "None" and "Millions of Colors+". In the layer window, on the "View" setting, make sure it is set to "All Layers". Now, with all that set up correctly, one simple way to create an alpha channel is to go to the Region Selection panel, create a region selection (say off of global color or something, it doesn't matter as long as you create a region selection). Now go up to Canvas > Set Layer Alpha To > Current Region Selection. The area will turn white (most likely, depending on your preferences). This white area is the transparent part. If you have another image in a layer underneath the current one with the Alpha Channel, you will now be able to see it through the areas that became transparent. If you don't have 2 or more layers you will just see white. Save the image as a PNG. Open it in Photoshop (if you have it). If you open it in p-shop then you will see the checkerboard pattern that indicates transparency in p-shop. Hope this makes sense.
The thing about the 'region fill as brush' pen mode is that the generated region is substituted for the normal source brush. And that would then override the source movie brush. So what i'm doing with the settings i mentioned is having the generated region just replace the source brush alpha and not the actual source brush rgb values. That way i can get the shape of the generated region while still filling it with the source movie frames.
You can think of alpha as a mask that is incorporated into the pixels of the image. Each pixel is composed of red, green, and blue color values. Alpha would be a mask value associated with the pixel. A pixel is a little square in the image. So an ARGB image buffer stores alpha, red, green. blue for each pixel.
Technically alpha is used to represent percent coverage, but it's probably easier to think of it as a mask.
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You can think of alpha as a mask that is incorporated into the pixels of the image. Each pixel is composed of red, green, and blue color values. Alpha would be a mask value associated with the pixel. A pixel is a little square in the image. So an ARGB image buffer stores alpha, red, green. blue for each pixel.
Technically alpha is used to represent percent coverage, but it's probably easier to think of it as a mask.