/// <summary>
/// Creates an atlas.
/// </summary>
/// <param name="atlas">The atlas.</param>
/// <param name="request">The request.</param>
/// <param name="atlasSizeIncrement">An indice used to increment the atlas size</param>
public void Create(TexAtlas atlas, AtlasCreationRequest request, int atlasSizeIncrement)
{
Log.Info("Creating atlas ...");
// Initalizing Atlas : trying to determine the minimum atlas size and allocating the needed memory
InitalizeAtlas(atlas, request, atlasSizeIncrement);
// Ordering textures in decreasing order : best heuristic with this algorithm.
if (atlasSizeIncrement == 0)
{
OrderTexture(request);
}
// Finding the best layout for the textures in the atlas
Node tree = PositionTextures(atlas, request);
// One of many textures couldn't be positioned which means the atlas is too small
if (tree == null)
{
Marshal.FreeHGlobal(atlas.Data);
Create(atlas, request, atlasSizeIncrement + 1);
}
else
{
// Everything went well, we can copy the textures data into the atlas
CopyTexturesIntoAtlasMemory(tree, atlas);
// Creating the atlas data
CreateAtlasData(tree, atlas, request.TextureList.Count);
}
}
/// <summary>
/// Determines the positions of the textures in the Atlas.
/// </summary>
/// <param name="atlas">The atlas.</param>
/// <param name="request">The request.</param>
/// <returns>The binary tree containing the positioned textures or null if the atlas is too small.</returns>
private Node PositionTextures(TexAtlas atlas, AtlasCreationRequest request)
{
Node root = new Node(0, 0, atlas.Width, atlas.Height);
foreach (TexImage texture in request.TextureList)
{
if (!Insert(root, texture))
{
return(null);
}
}
return(root);
}
/// <summary>
/// Orders the textures list in decreasing size.
/// </summary>
/// <param name="request">The request.</param>
private void OrderTexture(AtlasCreationRequest request)
{
QuickSort(request.TextureList, 0, request.TextureList.Count - 1);
}
/// <summary>
/// Initalizes the atlas. Predictes the minimum size required by the atlas according to the textures
/// </summary>
/// <param name="atlas">The atlas.</param>
/// <param name="request">The request.</param>
private void InitalizeAtlas(TexAtlas atlas, AtlasCreationRequest request, int atlasSizeIncrement)
{
// Calculating the total number of pixels of every texture to be included
int pixelCount = 0;
bool hasMipMap = false;
foreach (TexImage texture in request.TextureList)
{
pixelCount += texture.Width * texture.Height;
if (texture.MipmapCount > 1)
{
hasMipMap = true;
}
}
// setting the new size to the atlas
int alpha = (int)Math.Log(pixelCount, 2) + 1 + atlasSizeIncrement;
atlas.Width = (int)Math.Pow(2, alpha / 2);
atlas.Height = (int)Math.Pow(2, alpha - alpha / 2);
// If we want a square texture, we compute the max of the width and height and assign it to both
if (request.ForceSquaredAtlas)
{
int size = Math.Max(atlas.Width, atlas.Height);
atlas.Width = size;
atlas.Height = size;
}
// Setting the TexImage features
int rowPitch, slicePitch;
Tools.ComputePitch(atlas.Format, atlas.Width, atlas.Height, out rowPitch, out slicePitch);
atlas.RowPitch = rowPitch;
atlas.SlicePitch = slicePitch;
// Allocating memory
if (hasMipMap)
{
int dataSize = 0;
int mipmapCount = 0;
int w, h;
List <TexImage.SubImage> subImages = new List <TexImage.SubImage>();
w = atlas.Width;
h = atlas.Height;
while (w != 1 || h != 1)
{
Tools.ComputePitch(atlas.Format, w, h, out rowPitch, out slicePitch);
subImages.Add(new TexImage.SubImage()
{
Data = IntPtr.Zero,
DataSize = slicePitch,
Width = w,
Height = h,
RowPitch = rowPitch,
SlicePitch = slicePitch,
});
dataSize += slicePitch;
++mipmapCount;
w = w > 1 ? w >>= 1 : w;
h = h > 1 ? h >>= 1 : h;
}
atlas.DataSize = dataSize;
atlas.Data = Marshal.AllocHGlobal(atlas.DataSize);
atlas.SubImageArray = subImages.ToArray();
int offset = 0;
for (int i = 0; i < atlas.SubImageArray.Length; ++i)
{
atlas.SubImageArray[i].Data = new IntPtr(atlas.Data.ToInt64() + offset);
offset += atlas.SubImageArray[i].DataSize;
}
atlas.MipmapCount = mipmapCount;
}
else
{
atlas.DataSize = atlas.SlicePitch;
atlas.Data = Marshal.AllocHGlobal(atlas.DataSize);
atlas.SubImageArray[0].Data = atlas.Data;
atlas.SubImageArray[0].DataSize = atlas.DataSize;
atlas.SubImageArray[0].Width = atlas.Width;
atlas.SubImageArray[0].Height = atlas.Height;
atlas.SubImageArray[0].RowPitch = rowPitch;
atlas.SubImageArray[0].SlicePitch = slicePitch;
}
atlas.DisposingLibrary = this;
}
