//filament-android/com.google.android.filament/IndirectLight

IndirectLight

open class IndirectLight

IndirectLight is used to simulate environment lighting, a form of global illumination.

Environment lighting has a two components:

1. irradiance
2. reflections (specular component)

Environments are usually captured as high-resolution HDR equirectangular images and processed by the cmgen tool to generate the data needed by IndirectLight.

Currently IndirectLight is intended to be used for "distant probes", that is, to represent global illumination from a distant (i.e. at infinity) environment, such as the sky or distant mountains. Only a single IndirectLight can be used in a Scene. This limitation will be lifted in the future.

Creation and destruction

An IndirectLight object is created using the IndirectLight.Builder and destroyed by calling destroyIndirectLight.

 Engine engine = Engine.create();

 Scene scene = engine.createScene();

 IndirectLight environment = new IndirectLight.Builder()
             .reflections(cubemap)
             .irradiance(numBands, sphericalHarmonicsCoefficients)
             .build(engine);

 scene.setIndirectLight(environment);

Irradiance

The irradiance represents the light that comes from the environment and shines an object's surface. The irradiance is calculated automatically from the Reflections (see below), and generally doesn't need to be provided explicitly. However, it can be provided separately from the Reflections as Spherical Harmonics (SH) of 1, 2 or 3 bands, respectively 1, 4 or 9 coefficients.

Use the cmgen tool to generate the Spherical Harmonics for a given environment.

Reflections

The reflections on object surfaces (specular component) is calculated from a specially filtered cubemap pyramid generated by the cmgen tool.

See also

Constructors

Types

Functions