The Object Properties panel shows settings, specific to the currently selected objects. See the Shapes section for the shapes' parameters, here is the list of light source settings:
- Intensity - defines the level of light, emitted by the source. The resulting light is defined by all the lights in the scene, so if you want to make a darker shadow from one of the lights, you need to increase its intensity.
- Radius - the radius of the light source itself. Zero radius means point light and hard shadows, non-zero radius means volume light and soft shadows (and longer rendering).
- Cast shadows - defines whether the light source makes shadows or not.
- Attenuation - the Start and End parameters define the range where the light level fades from the maximum to zero. The Power parameter defines the speed of fading. "1" means linear fading, "2" means square fading and so on. You may turn the attenuation off by unchecking the box.