Light parameters

[gjcope]

In the (to my knowledge) currently available version of the draft 4.0 spec, the only defined light parameters are color, intensity, and angle (for spot lights). I may be remembering incorrectly, but I thought we had more previously defined? I also recall their being defined defaults for some as well. Apologies if I'm looking at the wrong document.

One parameter I'm particularly concerned with is "decay". If undefined, different default values in different implementations could end in drastically different results - from a well light scene to scene that appears to have no light at all. The scenario currently happens easily in the viewer I support (Voyager).

[JulieWinchester]

I think your reading is correct, from https://preview.iiif.io/api/prezi-4/presentation/4.0/model/#Light the light parameters currently supported include color, intensity, and angle (for spot lights only). The latest model draft also includes the language:

This specification does not define other aspects of Lights, such as the rate of decay of the intensity of the light over a distance, the maximum range of the light, or the penumbra of a cone. Implementation of these aspects is client-dependent.

For decay and maximum range or distance of a light, my question would be whether different frameworks handle this in an equivalent way that can be specified somewhat simply, and if so, how is it specified across frameworks?

[gjcope]

It depends on what you mean by how they "handle" the parameters. In my experience, most frameworks make use of these parameters in very similar ways, but sometimes choose very different defaults. I think the lack of a standard default is what could/would result in dramatically different experiences.