PixelBrush - Opacity inversion - Colour on Colour

[rsabbarton]

When painting colour over colour (in the same layer) the resulting opacity of the pixel is correct but the residual colour and new colour elements are inverse and less opacity reduces the amount of the original colour used instead of reducing the amount of the new colour used.

Steps to reproduce

• New sprite
• Flood Fill with any colour
• Select a contrasting colour
• Select default brush tool
• click once
• Notice how the new colour is applied more in the corners where the opacity is reduced.

[rsabbarton]

Fixed using color vectors. Interesting way to solve the problem. Will maybe write an article on it.