Tutorials using Fill Opacity
Fades an element’s interior from a percentage — how a screen says “still there, not in service”.
What Fill Opacity does
Fade an element’s interior from a number given as a percentage: 100 is fully painted, 0 is invisible.
Percent rather than a fraction, because the values that reach a widget parameter come from a plant and plants deal in percent. Feeding it 0.3 gives you an element that is very nearly gone.
Fading is a different statement from hiding, and usually a better one. A device that is de-energised, isolated or not yet commissioned is still there — it belongs on the screen, it is just not participating. Dropping it to about 30 says exactly that. Removing it says the plant does not have one, which is a lie the operator will act on.
It touches the fill only, so an outline stays at full strength. That is often what you want: a ghosted body inside a crisp frame still reads as an object, where fading both leaves a smudge. To make the whole thing recede, add Stroke Opacity as well.
