I have placed the height map in the normal map’s alpha channel.
However, when the texture is flagged as a normal map, the alpha channel is removed and the parallax no longer works correctly.
On the other hand if I set the normal map’s texture type to ‘texture’ the texture gets it’s alpha channel back and parallax shader now correctly uses it - but now the normal map does not work correctly and Unity keeps throwing up an error message wanting to ‘fix’ the texture.
The only way I have found to get both a normal map AND height map to display is to put the height map in it’s own texture, but this is not ideal as then I have to load another 32bit texture with three unused channels.
Am I missing something, why won’t normal maps keep their alpha channels?