Factorio Forums

LuaRendering.draw_circle appears to ignore color.alpha and blends using additive mode, so overlapping circles end up saturating.

Is there a way to change blend mode / force use of alpha?

Does this help?
Friday Facts #172 - Blending and Rendering

I was reminded recently that in general Factorio expects a premultiplied alpha colour - there is a pre-mult function in core/lualib/util.lua I often use.