overwriting built-in shader?

Questions & Answers
1

Is this supported by unity? I have found some forum/unity-answer posts which suggest it should work if you name you shader like the built-in ones but I don’t get it to work here:

If I for example create a custom Diffuse shader it is only used when I create a new material (defaulting to my custom diffuse shader), but pre-existing materials don’t use the custom one and if I choose the Diffuse shader the built-in is used instead of the custom shader.

2

Yes you can create your own shader. All you need to do is create one through the inspector. Once you have created a new shader it will be an option on the list of shaders on the material,

If you want to base your implementation from one of Unity's then you will need to download them from:

http://unity3d.com/downloadunity/builtinshaders.zip

Hope this helps!