after the "Pversion4" (8 bytes) comes the patch data version (4 bytes)
followed by the heightmap, vertex count, vertex data (int2), index count, index data, patch index, and layer data (layer count, layer index, layer index buffer size, layer index buffer, layer alpha map size, layer alpha map)
you can leave out the layer data by replacing it with a UINT32_MAX instead
the .bullet files contain physics data, I am not sure how well the terrain will load without it
