This page demonstrates how the mountain shader is made up.
You can download the mountain scene here.

After downloading unzip and open the scene in XSI ...

1. Select the grid.

2. Press update in the Render Tree window. There you see what is going on in the shader.

3. In case the picture for the displacement of the Mountain_grid called "Cloud_Sprite.tif" isn´t already in place locate the displacement subtree in the Render Tree, then go to the Net View and browse to: Library --> Pictures --> Sprites --> Cloud and drag & drop it onto the Cloud_Sprite.tif node.

4. With Q depressed, draw a render region in the Camera Viewport. Now you should see the mountain shown above.

5. For a better overview you may sort the tree like this:

6. The snowline is altered by the Change_range node that is further connected to the arrow´s y position in the scene. The arrow is already animated so for changing the border just move the timeline framewise or delete its animation and move it up or down.

7. For checking intermediate steps get yourself a scalar2color node by clicking on the nodes button in the Render Tree --> Nodes --> Conversion --> Scalar to Color and connect it to the surface input of the material node.

I hope you like this shader. Keep on experimenting with it and have fun.

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