Directional Light

What is correct or appropriate mapping of Directional Light parameters from COLLADA to OpenGL?
I tested some sample files with Diffuse only (no ambient nor specular).
It seems to me that this combination is good for most files.
(I used Mac OSX Preview application as a reference)
But it is too dark for “HatFromXSI.dae” from the model bank.
I also tested with Diffuse and Specular (no ambient),
but it is too bright for “BikeFromXSI.dae” .
Are there some coefficients for each light source components (diffuse, specular and ambient) to implement COLLADA directional light?


See page 120 (5-80 light) of the 1.5 spec for information on the light types and their attenuation.

Note that a directional light is not attenuated.

Also be aware that applications may introduce their own light sources into their rendered scenes.