LIGHTING

INTRODUCTION TO LIGHTING:

Dynamic lighting has been a feature of X-Plane for about a decade, beginning with X-Plane 9's landing light spill on aircraft. This has since been expanded to allow dynamic lighting to be used in many applications, called global illumination in X-Plane 10. In addition, V10 also introduces HDR rendering capabilities. For X-Plane 11, the way light is rendered is further improved with new rendering alongside PBR and a redeveloped lighting model.

TYPES OF LIGHT:

There are three main types of light usable in X-Plane: Named Lights, Parameterised Light, and Custom Light

NAMED LIGHTS (LIGHT_NAMED):

• Basic billboard light, existed since dinosaurs. Please don't use this.

PARAMETERISED LIGHTS (LIGHT_PARAM):

• Parameterised lights are default lighting in X-Plane 10 and 11, with default billboard textures and dynamic lighting support. Gives the ability for developers to adjust the spill (size, intensity, direction, angle) and the type of billboard light; usually written in two lines to configure the billboard and the spill.

CUSTOM LIGHTS:

• Custom Lights further extends parameterised lighting by enabling developers to provide a custom billboard texture and an assigned dataref

INSERTING LIGHTS INTO YOUR OBJECTS:

THIS SECTION IS REWORDED AND REFORMATTED FROM THE X-PLANE DEVELOPER BLOG

You may insert lights through opening your 3d object through a text editing program. Most developers uses parameterised lights, as it gives off flexibility in adjusting your spills (but lacks the ability for custom billboard textures, which will be covered in Custom Lights).

NAMED LIGHTS:

In a named light, the developer is limited to a pre-built in default billboard light, and the following three values determining the X-Y-X position. In this example, the named light is "obs_red_night":

LIGHT_NAMED obs_red_night -0.68 0.39 0

1. LIGHT NAME: LIGHT_NAMED

2. TYPE OF LIGHT: obs_red_night

3. X-Y-Z POSITION: First 3 numbers: -0.68 0.39 0 are the coordinates (this light is 0.39 meters above our object origin and 0.68 meters to the right).

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PARAMETERISED LIGHTS:

In a standard parameterised light, normally there are two lines: one configuring the appearance of the billboard texture, and the second defining the dynamic light properties. Most applications in scenery uses the parameterised light called "full_custom_halo":

LIGHT_PARAM full_custom_halo 0 20 0   1 0.5 0.5 1    50  0 -1 0   0.5 sim/graphics/animation/lights/airplane_navigation_light_dir

1. LIGHT NAME: LIGHT_PARAM

2. TYPE OF LIGHT: full_custom_halo

3. X-Y-Z POSITION: First 3 numbers: 0 20 0 are the coordinates (this light is 20 meters above our object origin).

4. RGBA COLOUR: 1 0.5 0.5 1 (100% red, 50% yellow, 50% green, 100% brightness), so it's a very light red. RGB colours for spills are in linear space, so some experimenting is necessary to perfect the colours.

5. SIZE IN METERS: The size is 50 meters (a huge light throw)

6. ANGLE OF DIRECTION: 0 -1 0 (straight down).

7. DATAREF: sim/graphics/animation/lights/airplane_navigation_light_dir to give custom animations/effects

0.5 is the "semi-width" of the cone - 60 degrees in this case. Basically cosine (cone width * 0.5) gives you this width parameter, or pass 1.0 for an omnidirectional light.

The billboard line are as follows:

LIGHT_PARAM  sodium_flood_BB    0 20 0 0 -0.5 -1 4

The same structure applies:

1. LIGHT NAME: LIGHT_PARAM

2. TYPE OF LIGHT: sodium_flood_BB

3. X-Y-Z POSITION: First 3 numbers: 0 20 0 are the coordinates (this light is 20 meters above our object origin).

4. RGBA COLOUR: 0 -0.5 -1 4 (0% red, 50% blue, 50% magenta, 400% brightness), so it's a very yellow/orange tint.

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CUSTOM LIGHTS:

Custom Lights further extends the flexibility of Parameterised lights by giving you the freedom to use your own billboard texture.

LIGHT_CUSTOM   0 20 0   1  0.5  0.5  1 5  sim/graphics/animation/lights/airplane_navigation_light_dir

1. LIGHT NAME: LIGHT_CUSTOM

2. X-Y-Z POSITION: First 3 numbers: 0 20 0 are the coordinates (this light is 20 meters above our object origin).

3. RGBA COLOUR: 1 0.5 0.5 1 (100% red, 50% yellow, 50% green, 100% brightness), so it's a very light red. RGB colours for spills are in linear space, so some experimenting is necessary to perfect the colours.

4. SIZE IN METERS: The size is 5 meters

5. TEXTURE COORDINATES: 0.5 1 1 0.5 (texture map is top right corner)

6. DATAREF: sim/graphics/animation/lights/airplane_navigation_light_dir to give custom animations/effects

TIPS:

• Use "full_custom_halo_night" for simple lighting that switches on at night.
• STANDARD LIGHT DIRECTIONS:

NORTH: -0.00 -1.00 -0.50

SOUTH: 0.00 -1.00 0.50

EAST: 0.50 -1.00 0.00

WEST: -0.50 -1.00 0.00