// Initialize the terrain geometry from height textures.
public void InitializeHeightsAndNormals()
{
var content = _services.GetInstance<ContentManager>();
// Create the height and normal texture for the 4 tiles.
// We can do this in parallel. We use following lock for parts which are not thread-safe.
var lockObject = new object();
Parallel.For(0, 2, row =>
//for (int row = 0; row < 2; row++)
{
Parallel.For(0, 2, column =>
//for (int column = 0; column < 2; column++)
{
string tilePostfix = "-" + row + "-" + column; // e.g. "-0-1"
var tile = _tiles[row, column];
var terrainTile = tile.TerrainTile;
// The height data is loaded from a 16-bit grayscale texture.
Texture2D inputHeightTexture;
lock (lockObject)
inputHeightTexture = content.Load<Texture2D>("Terrain/Terrain001-Height" + tilePostfix);
Debug.Assert(inputHeightTexture.Width == inputHeightTexture.Height, "This code assumes that terrain tiles are square.");
// The height textures of the tiles overlap by one texel to avoid gaps. That means, the
// input height texture for each tile is 1025 x 1025. The last texture column of the top
// left tile is the same as the first column of the top right tile. The last row of the
// top left tile is the same as the first row of the bottom left tile.
// The tile size in world space units is:
float tileSize = (inputHeightTexture.Width - 1) * terrainTile.CellSize;
terrainTile.OriginX = -tileSize + tileSize * column;
terrainTile.OriginZ = -tileSize + tileSize * row;
Debug.Assert(Numeric.IsZero(terrainTile.OriginX % terrainTile.CellSize), "The tile origin must be an integer multiple of the cell size.");
Debug.Assert(Numeric.IsZero(terrainTile.OriginZ % terrainTile.CellSize), "The tile origin must be an integer multiple of the cell size.");
// Extract the height values from the texture.
float[] heights = TerrainHelper.GetTextureLevelSingle(inputHeightTexture, 0);
// Transform height values from [0, 1] to [_minHeight, _maxheight].
TerrainHelper.TransformTexture(heights, (_maxHeight - _minHeight), _minHeight);
// Optional: Smooth the processed height map. (Very useful to remove artifacts from 8-bit
// height maps.)
TerrainHelper.SmoothTexture(heights, inputHeightTexture.Width, inputHeightTexture.Height, _smoothness);
// We have to create a height and normal texture for each tile.
// Reuse existing textures to avoid unnecessary allocation. (XNA can run out of memory
// if we allocate to many textures in a short time.)
Texture2D heightTexture = terrainTile.HeightTexture;
Texture2D normalTexture = terrainTile.NormalTexture;
// Convert the height value array into a suitable height texture.
TerrainHelper.CreateHeightTexture(
_graphicsService.GraphicsDevice,
heights,
inputHeightTexture.Width,
inputHeightTexture.Height,
_useNearestNeighborMipmaps,
ref heightTexture);
// Create a normal texture from the height values.
TerrainHelper.CreateNormalTexture(
_graphicsService.GraphicsDevice,
heights,
inputHeightTexture.Width,
inputHeightTexture.Height,
terrainTile.CellSize,
_useNearestNeighborMipmaps,
ref normalTexture);
// If terrainTile.HeightTexture/NormalTexture was null, then CreateHeight/CreateNormal
// has created a new texture. We have to dispose this textures in Dispose().
terrainTile.HeightTexture = heightTexture;
terrainTile.NormalTexture = normalTexture;
// Set the height field data for collision detection.
var heightField = (HeightField)tile.RigidBody.Shape;
heightField.OriginX = terrainTile.OriginX;
heightField.OriginZ = terrainTile.OriginZ;
heightField.WidthX = tileSize;
heightField.WidthZ = tileSize;
lock (lockObject)
{
heightField.SetSamples(heights, heightTexture.Width, heightTexture.Height);
heightField.Invalidate();
}
});
});
// Inform the terrain that the old texture content is invalid.
TerrainNode.Terrain.Invalidate();
}
