private void UpdateHoleTexture()
{
// Hole information could be loaded from a texture. Here, we procedurally create a pattern of
// holes.
// The hole buffer is array with 1 where there is no hole and 0 where there is a hole.
// (This is similar to an alpha mask: 1 = opaque, 0 = transparent.)
int numberOfSamples = _terrainObject.TerrainNode.Terrain.Tiles.First().HeightTexture.Width;
float[] holes = new float[numberOfSamples * numberOfSamples];
// Fill hole buffer with 1.
for (int i = 0; i < holes.Length; i++)
{
holes[i] = 1;
}
if (_holeSize > 0)
{
// Add some 0 elements to create holes.
int counterY = _holeSize;
for (int y = 0; y < numberOfSamples - 1; y++)
{
int counterX = _holeSize;
for (int x = 0; x < numberOfSamples - 1; x++)
{
holes[y * numberOfSamples + x] = 0;
counterX--;
if (counterX <= 0)
{
counterX = _holeSize;
x += _holeSize * 2;
}
}
counterY--;
if (counterY <= 0)
{
counterY = _holeSize;
y += _holeSize * 2;
}
}
}
// Copy hole buffer to a texture.
TerrainHelper.CreateHoleTexture(
GraphicsService.GraphicsDevice,
holes,
numberOfSamples,
numberOfSamples,
false,
ref _holeTexture);
foreach (var tile in _terrainObject.TerrainNode.Terrain.Tiles)
{
// Assign the hole texture to all terrain tiles. (Normally, each tile would have a
// different hole texture or no hole texture at all.)
tile.HoleTexture = _holeTexture;
// We also have to add the holes to the collision detection height fields.
// Get rigid body that represents this tile.
var rigidBody = Simulation.RigidBodies.First(body => body.UserData == tile);
var heightField = (HeightField)rigidBody.Shape;
// Update the height values of the collision detection height field.
float[] heights = TerrainHelper.GetTextureLevelSingle(tile.HeightTexture, 0);
for (int z = 0; z < numberOfSamples; z++)
{
for (int x = 0; x < numberOfSamples; x++)
{
if ((!(holes[z * numberOfSamples + x] > 0.5f)))
{
// The HeightField class treats NaN as holes.
heights[z * numberOfSamples + x] = float.NaN;
}
}
}
heightField.SetSamples(heights, numberOfSamples, numberOfSamples);
heightField.Invalidate();
}
_terrainObject.TerrainNode.Terrain.Invalidate();
}