/// <summary>
/// Updates or adds a new candidate to the list of candidate region, based on whether
/// the candidate already exists and whether the existing region is larger or smaller
/// than the new region.
/// </summary>
/// <param name="regions">The existing set of candidate regions.</param>
/// <param name="candidateRegion">The new candidate region to consider.</param>
private void UpdateOrAddCandidate(List <CandidateRegion> regions, CandidateRegion candidateRegion)
{
var existing =
regions.FirstOrDefault(
x => x.Position.X == candidateRegion.Position.X && x.Position.Y == candidateRegion.Position.Y);
if (existing == null)
{
regions.Add(candidateRegion);
}
else
{
if (existing.SizeW == null && candidateRegion.SizeW != null)
{
existing.SizeW = candidateRegion.SizeW;
}
else if (existing.SizeW > candidateRegion.SizeW)
{
existing.SizeW = candidateRegion.SizeW;
}
if (existing.SizeH == null && candidateRegion.SizeH != null)
{
existing.SizeH = candidateRegion.SizeH;
}
else if (existing.SizeH > candidateRegion.SizeH)
{
existing.SizeH = candidateRegion.SizeH;
}
}
}
/// <summary>
/// Pack the specified textures and return the placed textures, with the
/// total resulting size set into the <see cref="size"/> parameter.
/// </summary>
/// <param name="size">The total size .</param>
/// <returns>A list of packed textures.</returns>
public List <PackedTexture <T> > Pack(out Vector2 size)
{
var results = new List <PackedTexture <T> >();
// Create candidate list.
var candidates = new List <CandidateRegion>();
candidates.Add(new CandidateRegion
{
Position = new Vector2(0, 0),
SizeH = null,
SizeW = null
});
// Sort pending textures by size.
var sortedTextures = this.m_TexturesToPack.OrderByDescending(x => x.Size.LengthSquared()).ToList();
// Pack textures
while (sortedTextures.Count > 0)
{
var texture = sortedTextures[0];
var maxX = results.Count == 0 ? 0 : results.Select(x => x.Position.X + x.Size.X).Max();
var maxY = results.Count == 0 ? 0 : results.Select(x => x.Position.Y + x.Size.Y).Max();
// Evaluate candidate locations
CandidateRegion bestCandidate = null;
var minimalIncrease = 100000f;
foreach (var candidate in candidates)
{
if (candidate.Fits(texture.Size))
{
var outerX = candidate.Position.X + texture.Size.X;
var outerY = candidate.Position.Y + texture.Size.Y;
var increaseX = Math.Max(outerX - maxX, 0);
var increaseY = Math.Max(outerY - maxY, 0);
var maximalIncrease = Math.Max(increaseX, increaseY);
var pick = false;
if (bestCandidate == null)
{
pick = true;
}
else if (maximalIncrease < minimalIncrease)
{
pick = true;
}
else if (maximalIncrease == minimalIncrease &&
candidate.Position.LengthSquared() < bestCandidate.Position.LengthSquared())
{
pick = true;
}
if (pick)
{
bestCandidate = candidate;
minimalIncrease = maximalIncrease;
}
}
}
if (bestCandidate == null)
{
throw new InvalidOperationException("Should not get into this state!");
}
// Detect candidate interruption
var outerPosition = bestCandidate.Position + texture.Size;
foreach (var candidate in candidates.ToList())
{
if (candidate.Position.X < bestCandidate.Position.X && candidate.Position.Y <= outerPosition.Y &&
(candidate.SizeW == null ||
candidate.SizeW.Value + candidate.Position.X >= bestCandidate.Position.X))
{
// Outer position interrupts this candidate's area
candidates.Remove(candidate);
this.UpdateOrAddCandidate(
candidates,
new CandidateRegion
{
Position = candidate.Position,
SizeH = candidate.SizeH,
SizeW = bestCandidate.Position.X - candidate.Position.X
});
this.UpdateOrAddCandidate(
candidates,
new CandidateRegion
{
Position = new Vector2(bestCandidate.Position.X, outerPosition.Y),
SizeH =
candidate.SizeH == null
? null
: candidate.SizeH - (outerPosition.Y - candidate.Position.Y),
SizeW =
candidate.SizeW == null
? null
: candidate.SizeW - (bestCandidate.Position.X - candidate.Position.X)
});
}
if (candidate.Position.Y < bestCandidate.Position.Y && candidate.Position.X <= outerPosition.X &&
(candidate.SizeH == null ||
candidate.SizeH.Value + candidate.Position.Y >= bestCandidate.Position.Y))
{
// Outer position interrupts this candidate's area
candidates.Remove(candidate);
this.UpdateOrAddCandidate(
candidates,
new CandidateRegion
{
Position = candidate.Position,
SizeH = bestCandidate.Position.Y - candidate.Position.Y,
SizeW = candidate.SizeW
});
this.UpdateOrAddCandidate(
candidates,
new CandidateRegion
{
Position = new Vector2(bestCandidate.Position.X, outerPosition.Y),
SizeH =
candidate.SizeH == null
? null
: candidate.SizeH - (bestCandidate.Position.Y - candidate.Position.Y),
SizeW =
candidate.SizeW == null
? null
: candidate.SizeW - (outerPosition.X - candidate.Position.X),
});
}
}
// Replace the current candidate with two new candidates and yield the packed texture.
candidates.Remove(bestCandidate);
this.UpdateOrAddCandidate(
candidates,
new CandidateRegion
{
Position = new Vector2(bestCandidate.Position.X, outerPosition.Y),
SizeW = bestCandidate.SizeW,
SizeH = bestCandidate.SizeH == null ? null : bestCandidate.SizeH - texture.Size.Y
});
this.UpdateOrAddCandidate(
candidates,
new CandidateRegion
{
Position = new Vector2(outerPosition.X, bestCandidate.Position.Y),
SizeW = bestCandidate.SizeW == null ? null : bestCandidate.SizeW - texture.Size.X,
SizeH = bestCandidate.SizeH
});
results.Add(
new PackedTexture <T>
{
Position = bestCandidate.Position,
Size = texture.Size,
Texture = texture.Texture
});
sortedTextures.RemoveAt(0);
}
// Calculate maximum bounds.
var finalMaxX = results.Select(x => x.Position.X + x.Size.X).Max();
var finalMaxY = results.Select(x => x.Position.Y + x.Size.Y).Max();
size = new Vector2(finalMaxX, finalMaxY);
return(results);
}