The outputted values from the map code I wrote above gives values of 20 @ 1920x1080 (the resolution it was designed for), 5 @ 960x540 etc. It appears to scale correctly.

But that only scales to the width, correct? The strength variable is controlling a force value, which exerts in all directions, so I need that value to scale according to the total resolution, and not just the width. Also the aspect ratio is not expected to be uniform; ie I intend to display the sketch at 4:3 resolutions as well as 16:9 etc..

Right now the values are for 1080p (1920x1080) so in that case would I divide my value by 1920x1080 and then multiply by the window width*height?

For the moment I'm gonna just scale the values to the overall screen resolution (so 960x520, for example, results in a value that's 1/4 of the value at 1920x1080). Its not perfect but its close enough for now.