Vertical texture mapping

This is the process by which we combine two texture layers to correctly map a flat texture to vertical surfaces such as mountains and cliff faces. Some 3D engines can have some kind of vertical mapping built into a pixel shader which is very handy when available. However, we can't always rely on this; for our project we can assume the mobile platforms will require baked textures with correctly mapped vertical surfaces. We can create two layers to achieve accurate vertical mapping in the following manner:

• Create our first material layer for cliffs, we'll name this Mountains 0-90.

• Assign it a nice Canyon Rock texture (such as the arid2/canyon_rock01.tga texture as provided in the GROME texture library).

• Create a new mask, default values are fine for this example.

• In the parameters for the texture set the UV tiling to something that fits the scene (for example 20, 20). Set the HV spin for this layer to 0, 90. This is shown in the following screenshot.

• Now the tricky part...