I am trying to determine what would be a sensible default colour for 'diffuse' in a lambert element when a texture rather than a colour is provided. Checking the documentation reveals the following:
The duck included in the model bank has the following colours:The schema does not specify default colors for <ambient>, <diffuse> and other child elements of the shaders <blinn>, <constant>, <lambert>, and <phong>. If any child element is unspecified, apply the specified shader equation without that portion. This provides equivalent results to explicitly specifying black for that child element.
1. An emission of 0,0,0,1.
2. An ambient of 0,0,0,1.
3. A diffuse texture rather than a diffuse colour.
4. A specular of 0,0,0,1.
As you can see, there is a diffuse texture rather than a diffuse colour and so technically the diffuse element is present. In this scenario, what should be the default for the diffuse colour please?
If I choose black then the duck appears black (due to the lack of emission, ambient or specular) but if I choose 0.8 (the OpenGL default) then the duck appears acceptably lit. However, choosing 0.8 goes against the specification.