/// <summary>
/// Builds a composited terrain texture given the region texture
/// and heightmap settings
/// </summary>
/// <param name="heightmap">Terrain heightmap</param>
/// <param name="regionInfo">Region information including terrain texture parameters</param>
/// <returns>A composited 256x256 RGB texture ready for rendering</returns>
/// <remarks>Based on the algorithm described at http://opensimulator.org/wiki/Terrain_Splatting
/// </remarks>
public static Bitmap Splat(float[] heightmap, UUID[] textureIDs, float[] startHeights, float[] heightRanges, Vector3d regionPosition, IAssetClient assetClient)
{
Debug.Assert(heightmap.Length == 256 * 256);
Debug.Assert(textureIDs.Length == 4);
Debug.Assert(startHeights.Length == 4);
Debug.Assert(heightRanges.Length == 4);
// Swap empty terrain textureIDs with default IDs
for (int i = 0; i < textureIDs.Length; i++)
{
if (textureIDs[i] == UUID.Zero)
textureIDs[i] = DEFAULT_TERRAIN_DETAIL[i];
}
#region Texture Fetching
Bitmap[] detailTexture = new Bitmap[4];
if (assetClient != null)
{
for (int i = 0; i < 4; i++)
{
Asset asset;
UUID cacheID = UUID.Combine(TEXTURE_CACHE_MAGIC, textureIDs[i]);
// Try to fetch a cached copy of the decoded/resized version of this texture
if (assetClient.TryGetCachedAsset(cacheID, "image/png", out asset))
{
try
{
using (System.IO.MemoryStream stream = new System.IO.MemoryStream(asset.Data))
detailTexture[i] = (Bitmap)Image.FromStream(stream);
}
catch (Exception ex)
{
m_log.Warn("Failed to decode cached terrain texture " + cacheID +
" (textureID: " + textureIDs[i] + "): " + ex.Message);
}
}
if (detailTexture[i] == null)
{
// Try to fetch the original JPEG2000 texture, resize if needed, and cache as PNG
if (assetClient.TryGetAsset(textureIDs[i], "image/x-j2c", out asset))
{
try { detailTexture[i] = (Bitmap)CSJ2K.J2kImage.FromBytes(asset.Data); }
catch (Exception ex)
{
m_log.Warn("Failed to decode terrain texture " + asset.ID + ": " + ex.Message);
}
}
if (detailTexture[i] != null)
{
Bitmap bitmap = detailTexture[i];
// Make sure this texture is the correct size, otherwise resize
if (bitmap.Width != 256 || bitmap.Height != 256)
bitmap = Util.ResizeImage(bitmap, 256, 256);
// Save the decoded and resized texture to the cache
byte[] data;
using (System.IO.MemoryStream stream = new System.IO.MemoryStream())
{
bitmap.Save(stream, ImageFormat.Png);
data = stream.ToArray();
}
assetClient.StoreAsset(
new Asset
{
ContentType = "image/png",
CreationDate = DateTime.UtcNow,
CreatorID = UUID.Zero,
Data = data,
ID = cacheID,
Local = true,
Temporary = true
}
);
}
}
}
}
// Fill in any missing textures with a solid color
for (int i = 0; i < 4; i++)
{
if (detailTexture[i] == null)
{
// Create a solid color texture for this layer
detailTexture[i] = new Bitmap(256, 256, PixelFormat.Format24bppRgb);
using (Graphics gfx = Graphics.FromImage(detailTexture[i]))
{
using (SolidBrush brush = new SolidBrush(DEFAULT_TERRAIN_COLOR[i]))
gfx.FillRectangle(brush, 0, 0, 256, 256);
}
}
}
#endregion Texture Fetching
#region Layer Map
float[] layermap = new float[256 * 256];
for (int y = 0; y < 256; y++)
{
for (int x = 0; x < 256; x++)
{
float height = heightmap[y * 256 + x];
float pctX = (float)x / 255f;
float pctY = (float)y / 255f;
// Use bilinear interpolation between the four corners of start height and
// height range to select the current values at this position
float startHeight = Util.Bilinear(
startHeights[0],
startHeights[2],
startHeights[1],
startHeights[3],
pctX, pctY);
startHeight = Utils.Clamp(startHeight, 0f, 255f);
float heightRange = Util.Bilinear(
heightRanges[0],
heightRanges[2],
heightRanges[1],
heightRanges[3],
pctX, pctY);
heightRange = Utils.Clamp(heightRange, 0f, 255f);
// Generate two frequencies of perlin noise based on our global position
// The magic values were taken from http://opensimulator.org/wiki/Terrain_Splatting
Vector3 vec = new Vector3
(
((float)regionPosition.X + x) * 0.20319f,
((float)regionPosition.Y + y) * 0.20319f,
height * 0.25f
);
float lowFreq = Perlin.noise2(vec.X * 0.222222f, vec.Y * 0.222222f) * 6.5f;
float highFreq = Perlin.turbulence2(vec.X, vec.Y, 2f) * 2.25f;
float noise = (lowFreq + highFreq) * 2f;
// Combine the current height, generated noise, start height, and height range parameters, then scale all of it
float layer = ((height + noise - startHeight) / heightRange) * 4f;
if (Single.IsNaN(layer)) layer = 0f;
layermap[y * 256 + x] = Utils.Clamp(layer, 0f, 3f);
}
}
#endregion Layer Map
#region Texture Compositing
Bitmap output = new Bitmap(256, 256, PixelFormat.Format24bppRgb);
BitmapData outputData = output.LockBits(new Rectangle(0, 0, 256, 256), ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);
unsafe
{
// Get handles to all of the texture data arrays
BitmapData[] datas = new BitmapData[]
{
detailTexture[0].LockBits(new Rectangle(0, 0, 256, 256), ImageLockMode.ReadOnly, detailTexture[0].PixelFormat),
detailTexture[1].LockBits(new Rectangle(0, 0, 256, 256), ImageLockMode.ReadOnly, detailTexture[1].PixelFormat),
detailTexture[2].LockBits(new Rectangle(0, 0, 256, 256), ImageLockMode.ReadOnly, detailTexture[2].PixelFormat),
detailTexture[3].LockBits(new Rectangle(0, 0, 256, 256), ImageLockMode.ReadOnly, detailTexture[3].PixelFormat)
};
int[] comps = new int[]
{
(datas[0].PixelFormat == PixelFormat.Format32bppArgb) ? 4 : 3,
(datas[1].PixelFormat == PixelFormat.Format32bppArgb) ? 4 : 3,
(datas[2].PixelFormat == PixelFormat.Format32bppArgb) ? 4 : 3,
(datas[3].PixelFormat == PixelFormat.Format32bppArgb) ? 4 : 3
};
for (int y = 0; y < 256; y++)
{
for (int x = 0; x < 256; x++)
{
float layer = layermap[y * 256 + x];
// Select two textures
int l0 = (int)Math.Floor(layer);
int l1 = Math.Min(l0 + 1, 3);
byte* ptrA = (byte*)datas[l0].Scan0 + y * datas[l0].Stride + x * comps[l0];
byte* ptrB = (byte*)datas[l1].Scan0 + y * datas[l1].Stride + x * comps[l1];
byte* ptrO = (byte*)outputData.Scan0 + y * outputData.Stride + x * 3;
float aB = *(ptrA + 0);
float aG = *(ptrA + 1);
float aR = *(ptrA + 2);
float bB = *(ptrB + 0);
float bG = *(ptrB + 1);
float bR = *(ptrB + 2);
float layerDiff = layer - l0;
// Interpolate between the two selected textures
*(ptrO + 0) = (byte)Math.Floor(aB + layerDiff * (bB - aB));
*(ptrO + 1) = (byte)Math.Floor(aG + layerDiff * (bG - aG));
*(ptrO + 2) = (byte)Math.Floor(aR + layerDiff * (bR - aR));
}
}
for (int i = 0; i < 4; i++)
detailTexture[i].UnlockBits(datas[i]);
}
output.UnlockBits(outputData);
// We generated the texture upside down, so flip it
output.RotateFlip(RotateFlipType.RotateNoneFlipY);
#endregion Texture Compositing
return output;
}