I want to document the workflow I use for painting complex scenes with multiple light sources, which requires more deliberate planning than single-source lighting.

Step one: identify every light source in the scene and characterize each one. Color temperature, intensity, proximity, direction. A scene with a warm fire on the left and a cool moonlight from above has two light sources with very different characteristics.

Step two: for each major surface, determine which light source is dominant and which is secondary. A surface directly facing the fire is primarily fire-lit with some moonlight as ambient fill. A surface facing away from the fire is primarily moonlit with firelight as ambient.

Step three: establish the color of shadow for each surface. The shadow color is the ambient light that fills the shadow area when the primary source is blocked. Near the fire: fire shadows have moonlit fill color. Far from the fire: moonlit shadows are very dark with minimal fill.

Step four: paint the base illumination for each surface, then add the secondary light source as a separate pass. The separation prevents the lights from mixing into mud.