Improved Vertex Color/Alpha Painting Tools

[rkovach]

Vertex Color has many uses outside of defining a Color and Opacity. Vertex Color RGBA Channels are often used to pass Blind Data to Real-Time Shaders to create special effects.

The Paint Vertex Color Tool is quite limited in what it can do. Please expand the options to be more conducive to editing the data in each channel separately. Allow the Paint Vertex Color Tool to view, and operate, on individual RGBA Channels. When an individual channel is selected, please display the data as Grayscale (even for the Alpha Channel).

Allow for the Paint Vertex Color Tool to operate on only the Alpha channel of a RGBA color set. Currently the Paint Tool must always update all four RGBA channels with every stroke (the "A" option is disabled for RGBA color sets, and only available if the color set itself is only a single channel of data).

When editing the Alpha, the Color is also replaced. Its not possible to Paint the Alpha data without modifying the Color. The current workaround is to use Add and Subtract with Color Set to Black in order to paint the alpha with disturbing the Colors.