I've created a spherical terrain object out of 6 sphere projected (normalised) planes, each plane has been heightmapped post to being normalised.
I'm looking to create a CG shader which will firstly calculate the slope of the heightmapped terrain, I understand this will need to look at the normals to calculate this can anyone elaborate on this for me? The next problem is that I want to do the slope calculations based upon the terrain "flat" rather than normalised.
Would it be best to either reverse the normalisation of the vertices during the slope calculations, or pre calculate and store the vertices slope data (on the flat plane) during the mesh generation?
This is an example of what I want to achieve with the shader:
Any suggestions would be brilliant.
Update in response to opatut answer:
I've output the current slope data based of how I "think" was suggested and these were the results:
I think my issue is that as each plane begins to curve that curve is includes as a slope which is the obvious thing to happen. I want to "flatten" out each of the 6 planes again for the slope calculations.