* HDRP: Add support of light layering for forward (first draft)
TODO:
- Test instancing
- Check perf
- add an option to disable light layer support + in frameSettings
- add deferred rendering support (mean add an optional extra GBuffer)
* Add LightLinking support (version 1 - compile)
This PR add support of LightLayers feature.
To use it, setup mask renderingLayers on renderers and LightLayers on a lights. If a logical and of both give a non 0 value, the light is apply, otherwise it isn't.
This mean that by default LightLayers is 1 and RenderingLayers is 1. Then user can say LightLayers is only 2 and it will only affect renderingLayers with 2 or 3 mask value.
LightLayers require an extra GBuffer in deferred, mean it have extra bandwidth and memory cost.
LightLayers once enabled in HDRPAsset with SupportLightLayers can be control by FrameSettings. Mean a camera can enable extra RT only for an in game cinematic.
This PR refactor...