The following built-in lights are available in Arnold from the Plugins > C4DtoA > Arnold Light menu:
- Cylinder light
- Disk light
- Distant light
- Mesh light
- Photometric light
- Point light
- Quad light
- Spot light
- Skydome Light
Lights are displayed in the viewport like the standard C4D Light object. Technically the settings are mapped to a standard C4D light model that's why the following limitations apply:
Arnold specific settings (like. color texture, radius, etc.) are not supported.
Skydome light is not supported.
Viewport display can be disabled via the Show in Editor flag on the Light tab. Also, the intensity in the viewport can be modified using the Intensity scale in Editor parameter.
Arnold does not support constant light decay. However, Arnold's Quad and Disk area lights have a Spread parameter, that when set to a low value, will give you something similar to a constant fall-off. Similarly, the Spotlight in Arnold has a Lens Radius parameter that, when set to a non-zero value, and coupled with a low angle, has the apparent effect of flattening the decay, like in a Hollywood-style searchlight. Another workaround is to use distant/directional lighting.
You can also use standard Cinema 4D lights when rendering with C4DtoA. To access the Arnold parameters you must add an Arnold tag to them (C4DtoA Tags > Arnold Parameters).
If you do not add an Arnold tag to the Light, Arnold specific parameters are exported with default values.
The light model in C4D and Arnold might be different since there's no one-to-one mapping in all cases.