Lighting

This article is a stub. You should help Wolfire by expanding it.

TODO: Cover other level parameters, such as HDR points, saturation, and sky brightness. These parameters are covered in the Script Parameters page, so might want to take care to not duplicate too much of the information and maybe include a link to that page
TODO: Expand sun section to say how to get a "sun" and a "moon" effect

Sunlight

The sun allows you to cast dynamic, single-directional light throughout a level.
You can use it to simulate either a sun (more direct light) or a moon (more ambient light)

The sun editor

Editing the sun and sky

How to adjust the sun

Select the sun in the sky (double click it)
Move it by clicking on the middle and dragging it around
Change the color by dragging the dot around the outer ring
Change the intensity by clicking just outside the outer ring and dragging it

To deselect the sun, double click well outside of the sun editor (Note: the normal Q for "deselect all" isn't working right now)

How to edit the parameters directly

If you have problems clicking it, or would prefer a numeric editor:

Press the Y key to open the Scenegraph
Expand level to find the Sun parameters

Reflection Capture

Reflection capture objects are used for ambient lighting, reflections, and the color of the fog in each direction.

There are two kinds of reflection capture objects, Global Reflection and Local Reflection. Both can be found under Load -> Lighting. A global reflection capture can be turned into a local one and vice versa by setting its Global script parameter to 1 or not.

Gotchas

Reflection captures are updated when moved, and each new result builds on the results of the previous reflection capture. This can be used to achieve some desired effect, but can also make it harder to get what you want sometimes. Try playing around with changing the brightness of the sky, amount of fog etc. to get different effects.

Certain level shaders will cause an issue where the sky will increase in brightness. To avoid this, disable the level shader temporarily. If the shader is important to include in the reflection capture, you can update it a single time by adjusting its position slightly within the Selected window.

Global reflection

Global reflection captures are used for the entire level, and each level should have exactly one. Since it affects the entire level it is often placed in a location that represents some sort of "average" lighting for the level.

Local reflection

Local reflection captures are used to change what the reflections look like in a specific region of the level. These are useful if there are caves or other types of areas where the ambient lighting changes significantly from the rest of the level. Move, rotate and scale the object to decide what part of the level should be affected.

Point lights

Point lights allow you to cast omni-directional light from a point in the level.

Adding and editing point lights

Adding a dynamic light:

Top Bar -> Load -> Lighting -> Dynamic Light
The cursor will turn into a plus symbol
Click in level to place the dynamic light

Changing the size of a dynamic light

Select the light - double click
Hold E while clicking and dragging on its bounding box.

Note that this only changes the light's area of influence, not how much light it outputs.

Making a dynamic light brighter

Select the light - double click
Open the color picker - Ctrl + P (Command + P on mac)
Change the Overbright setting

Adjusting dynamic light color:

Select the light
Hit CTRL + P (command + P on mac) to open the Color Picker.
Adjust the color with the color selector, or RGB at the bottom.

Shaping the dynamic light

Dynamic lights are always spherical right now. If you need an "area light" effect that isn't a sphere, there are a few options:

Use Shadow Decals to shape the light (you have to enable this in the level first. See this section below)
Place multiple dynamic light objects
Some combination of both of the above

Be careful to both look at how the lights affect static objects in the scene, and how they affect characters that walk through them.

Shadow decals

Shadows from sunlight are taken care of automatically.

However this only allows one level of shadowing. This doesn't handle ambient occlusion (shadowing of indirect light reflections).

Shadow decals ("Ambient Shadows") allow you to manually place decals which simulate this ambient occlusion effect.
This can help you visually anchor objects more realistically in the scene, and replicate effects like darkening around corners, and inside cubbyholes.

Adding and editing ambient shadows

Adding a shadow decal:

Top Bar -> Load -> Lighting -> Ambient Shadow.
The cursor will turn into a plus symbol.
Now click in level to place the ambient shadow decal.

Resizing a shadow decal:

Double click the ambient shadow decal, and hold E while clicking and dragging on its bounding box (or while shift + right-clicking and dragging on a side to only stretch in that direction).
This will let you increase the spread of its effect.

Note: Ambient shadow decals will not create shadows if they in direct light. This is because they're for simulating indirect shadowing. Direct shadowing is already handled by placing objects in the world.

Dynamic lights and shadows

By default, no objects cast shadows from dynamic point lights (besides the sun). This is for performance reasons.

Normally ambient shadow decals also will not create shadow from dynamic point lights, because that would be shading direct light, and they don't work that way.

However you can use the #SHADOW_POINT_LIGHTS level Custom Shader to make it so shadow decals can shape point lights, so you can manually simulate this shadowing.

Making shadow decals affect dynamic lights:

Hit Y to open the level's scenegraph
Expand Script Params
Add a Custom Shader param
Hit Enter (not tab!)
Type #SHADOW_POINT_LIGHTS in the value column and hit enter

This will make ambient shadows affect the direct light from dynamic lights, an let you sculpt the light they cast, or let you create manual shadows.