2D Panel Lighting Tips

Here are a few tips for 2-d panel lighting.

=Creating Glow Effects With Default Instruments=

In X-Plane 930 you can use "additive" lighting with the default instruments - set the lighting mode to "additive" in Plane-Maker and add _LIT-1, _LIT-2 textures etc. to the overlays.

This effect is typically used to make LEDs and back-lit numbers have a warm "glow" at night.

There are two problems with this technique. First, additive lighting can only be used on the overlays of an instrument, e.g. the -1, -2, -3 and -4 layers. So there is no way to make the background glow. For example, if an instrument has its numbers and markings in the background, those can't be made to glow.

The work-around is to make a new instrument, typically a generic rotary with 1 image cell and no click mode, with additive lighting mode and the image of the glow. The glow goes in the -1 layer.

This glow instrument must be lower in the panel "stack" than the instrument you want to glow. The glow will appear on top of the background (since all backgrounds are drawn before any overlays) but under the moving parts of the regular instrument (which is higher in the sack).

For an example of this, see the default C172 in X-Plane 930 or newer. Since the steam gauges have their markings in the background, the author uses a single large generic to add all the glow effects to the six-pack instruments.

The second problem is that default instruments automatically categorize their layers into lit vs. mechanical lighting...the "additive" option only affects those "mechanical" layers. For example, in the radio stack, the LEDs are automatically categorized as "lit", so additive lighting is not available for them.

Usually this is not a problem - if the layer is lit, you wouldn't need glow because the lit texture would already contain this.

=Per-Pixel vs. Per-Vertex Limitations=

The 2-d "lighting" masks (-2, -3, and -4 layers on the panel background) add light to the panel and instrument background and any burned in elements on a per-pixel basis.

However, due to performance limitations, these effects only affect overlays on a per-vertex basis. That is, the entire overlay is lit uniformly by the -2,-3, or -4 mask based on one sampling point. (The same is true for the -1 shadow layer.)

There is no one good work-around for this...typically you will have to use a combination of careful shaping of the background lighting effects and possible use of lighting overlays to reduce artifacts.