Time for action – multitexturing

1. 1. In the declarations area of the Terrain.fx effect file, add two new texture variables to hold the additional textures we will be using, as follows:

   texture terrainTexture2;
   texture terrainTexture3;

2. 2. Still in the declarations area, add samplers for the new textures as follows:

   sampler2D textureSamplerMid = sampler_state {
     Texture = (terrainTexture2);
     AddressU = Wrap;
     AddressV = Wrap;
   };
   
   sampler2D textureSamplerHigh = sampler_state {
     Texture = (terrainTexture3);
     AddressU = Wrap;
     AddressV = Wrap;
   };

3. 3. Also in the declarations area, add the following items to control how the textures are split between elevations:

   float maxElevation;
   float trans1 = 0.50;
   float trans2 = 0.75;

4. 4. In the VertexShaderOutput structure, add a new structure member to allow us to pass the elevation of the current vertex to the pixel shader as follows:

   float Elevation : TEXCOORD1;

5. 5. In the VertexShaderFunction() method, right after declaring the output variable, store the...