protected static bool TestRangeForFreeSpace(VoxelField volume, Vector3i start, Vector3i end)
{
// 1. Ignore directions that take us outside the bounds of the voxel volume.
if (start.X < 0 || start.Y < 0 || start.Z < 0)
{
return(false);
}
// 2. Ensure that we can safely expand into the area, expand as long as the voxel isn't empty.
// Note: it is ok to expand into a space already occupied.
for (Int32 z = start.Z; z <= end.Z; ++z)
{
for (Int32 y = start.Y; y <= end.Y; ++y)
{
for (Int32 x = start.X; x <= end.X; ++x)
{
byte value = volume.GetVoxel(x, y, z);
// If a voxel has a '1' then it's unused volume space, if it is '0' it is empty,
// and if anything else, it has a box in it already.
if (value != 1)
{
return(false);
}
}
}
}
return(true);
}
protected static float MeasureUnboxedVoxels(VoxelField volume)
{
int unboxedVoxels = 0;
int totalvoxels = 0;
for (Int32 x = 0; x < volume.VoxelSize.X; ++x)
{
for (Int32 y = 0; y < volume.VoxelSize.Y; ++y)
{
for (Int32 z = 0; z < volume.VoxelSize.Z; ++z)
{
byte value = volume.GetVoxel(x, y, z);
if (value == 1)
{
unboxedVoxels++;
}
if (value != 0)
{
totalvoxels++;
}
}
}
}
return(unboxedVoxels / (float)totalvoxels);
}
void ComputeNext(Random random, AABBi current, AABBi next, VoxelField volume, ref Vector3i densestVoxel, long delta, double temperature)
{
current.Clone(next);
do
{
double probability = random.NextDouble();
if (probability < Math.Exp(-delta / temperature))
{
next.MinX = densestVoxel.X + random.Next(0 - densestVoxel.X, 0);
}
probability = random.NextDouble();
if (probability < Math.Exp(-delta / temperature))
{
next.MinY = densestVoxel.Y + random.Next(0 - densestVoxel.Y, 0);
}
probability = random.NextDouble();
if (probability < Math.Exp(-delta / temperature))
{
next.MinZ = densestVoxel.Z + random.Next(0 - densestVoxel.Z, 0);
}
probability = random.NextDouble();
if (probability < Math.Exp(-delta / temperature))
{
next.MaxX = densestVoxel.X + random.Next(0, volume.VoxelSize.X - densestVoxel.X) + 1;
}
probability = random.NextDouble();
if (probability < Math.Exp(-delta / temperature))
{
next.MaxY = densestVoxel.Y + random.Next(0, volume.VoxelSize.Y - densestVoxel.Y) + 1;
}
probability = random.NextDouble();
if (probability < Math.Exp(-delta / temperature))
{
next.MaxZ = densestVoxel.Z + random.Next(0, volume.VoxelSize.Z - densestVoxel.Z) + 1;
}
} while (!TestRangeForFreeSpace(volume,
new Vector3i(next.MinX, next.MinY, next.MinZ),
new Vector3i(next.MaxX, next.MaxY, next.MaxZ)));
}
protected static Vector3i FindHighestDensityVoxel(VoxelField volume)
{
float denestDistance = float.MinValue;
Vector3i densestVoxel = new Vector3i(0, 0, 0);
Object syncroot = new Object();
Parallel.For(0, volume.VoxelSize.Z, z =>
{
for (Int32 y = 0; y < volume.VoxelSize.Y; ++y)
{
for (Int32 x = 0; x < volume.VoxelSize.X; ++x)
{
byte value = volume.GetVoxel(x, y, z);
// Ignore empty voxels and already boxed voxels
if (value != 1)
{
continue;
}
float closestExtDist = FindShortestDistanceToAbnormalVoxel(volume, x, y, z);
if (closestExtDist > denestDistance)
{
lock (syncroot)
{
if (closestExtDist > denestDistance)
{
denestDistance = closestExtDist;
densestVoxel = new Vector3i(x, y, z);
}
}
}
}
}
});
return(densestVoxel);
}
protected static bool FillRange(VoxelField volume, Vector3i start, Vector3i end, Byte fillByte)
{
// 1. Ensure that we can safely expand into the area.
if (!TestRangeForFreeSpace(volume, start, end))
{
return(false);
}
// 2. Fill area
for (Int32 z = start.Z; z <= end.Z; ++z)
{
for (Int32 y = start.Y; y <= end.Y; ++y)
{
for (Int32 x = start.X; x <= end.X; ++x)
{
volume.SetVoxel(x, y, z, fillByte);
}
}
}
return(true);
}
protected static float FindDistanceToAbnormalVoxelInRange(
VoxelField volume,
Vector3i voxel,
int startX, int startY, int startZ,
int endX, int endY, int endZ)
{
// 1. Ignore directions that take us outside the bounds of the voxel volume.
if (startX < 0 || startY < 0 || startZ < 0)
{
return(float.MaxValue);
}
float closestValueDist = float.MaxValue;
// 2. Find the value along the axis
for (Int32 z = startZ; z <= endZ; ++z)
{
for (Int32 y = startY; y <= endY; ++y)
{
for (Int32 x = startX; x <= endX; ++x)
{
byte value = volume.GetVoxel(x, y, z);
if (value != 1)
{
float dist = (float)(voxel - new Vector3i(x, y, z)).LengthSquared;
if (dist < closestValueDist)
{
closestValueDist = dist;
}
}
}
}
}
return(closestValueDist);
}
protected static bool TestRangeForFreeSpace(VoxelField volume, AABBi box)
{
return(TestRangeForFreeSpace(volume, new Vector3i(box.MinX, box.MinY, box.MinZ), new Vector3i(box.MaxX - 1, box.MaxY - 1, box.MaxZ - 1)));
}
protected static AABBi ExpandAndFillBox(VoxelField volume, ref Vector3i originVoxel, Byte fillByte)
{
int pX, nX, pY, nY, pZ, nZ;
pX = nX = pY = nY = pZ = nZ = 0;
volume.SetVoxel(originVoxel.X, originVoxel.Y, originVoxel.Z, fillByte);
bool boxGrew = false;
do
{
// +Z Axis
bool pZGrew = FillRange(volume,
new Vector3i(originVoxel.X - nX, originVoxel.Y - nY, originVoxel.Z + (pZ + 1)),
new Vector3i(originVoxel.X + pX, originVoxel.Y + pY, originVoxel.Z + (pZ + 1)), fillByte);
if (pZGrew)
{
pZ++;
}
// -Z Axis
bool nZGrew = FillRange(volume,
new Vector3i(originVoxel.X - nX, originVoxel.Y - nY, originVoxel.Z - (nZ + 1)),
new Vector3i(originVoxel.X + pX, originVoxel.Y + pY, originVoxel.Z - (nZ + 1)), fillByte);
if (nZGrew)
{
nZ++;
}
// +Y Axis
bool pYGrew = FillRange(volume,
new Vector3i(originVoxel.X - nX, originVoxel.Y + (pY + 1), originVoxel.Z - nZ),
new Vector3i(originVoxel.X + pX, originVoxel.Y + (pY + 1), originVoxel.Z + pZ), fillByte);
if (pYGrew)
{
pY++;
}
// -Y Axis
bool nYGrew = FillRange(volume,
new Vector3i(originVoxel.X - nX, originVoxel.Y - (nY + 1), originVoxel.Z - nZ),
new Vector3i(originVoxel.X + pX, originVoxel.Y - (nY + 1), originVoxel.Z + pZ), fillByte);
if (nYGrew)
{
nY++;
}
// +X Axis
bool pXGrew = FillRange(volume,
new Vector3i(originVoxel.X + (pX + 1), originVoxel.Y - nY, originVoxel.Z - nZ),
new Vector3i(originVoxel.X + (pX + 1), originVoxel.Y + pY, originVoxel.Z + pZ), fillByte);
if (pXGrew)
{
pX++;
}
// -X Axis
bool nXGrew = FillRange(volume,
new Vector3i(originVoxel.X - (nX + 1), originVoxel.Y - nY, originVoxel.Z - nZ),
new Vector3i(originVoxel.X - (nX + 1), originVoxel.Y + pY, originVoxel.Z + pZ), fillByte);
if (nXGrew)
{
nX++;
}
boxGrew = (pZGrew || nZGrew || pYGrew || nYGrew || pXGrew || nXGrew);
} while (boxGrew);
AABBi box = new AABBi();
box.MinX = originVoxel.X - nX;
box.MinY = originVoxel.Y - nY;
box.MinZ = originVoxel.Z - nZ;
box.MaxX = originVoxel.X + pX + 1;
box.MaxY = originVoxel.Y + pY + 1;
box.MaxZ = originVoxel.Z + pZ + 1;
return(box);
}
protected static bool FillRange(VoxelField volume, AABBi box, Byte fillByte)
{
return(FillRange(volume, new Vector3i(box.MinX, box.MinY, box.MinZ), new Vector3i(box.MaxX - 1, box.MaxY - 1, box.MaxZ - 1), fillByte));
}
protected static float FindShortestDistanceToAbnormalVoxel(VoxelField volume, int x, int y, int z)
{
int pX, nX, pY, nY, pZ, nZ;
pX = nX = pY = nY = pZ = nZ = 0;
Vector3i voxel = new Vector3i(x, y, z);
do
{
// +Z Axis
float distance = FindDistanceToAbnormalVoxelInRange(volume, voxel,
x - nX, y - nY, z + (pZ + 1),
x + pX, y + pY, z + (pZ + 1));
if (distance != float.MaxValue)
{
return(distance);
}
pZ++;
// -Z Axis
distance = FindDistanceToAbnormalVoxelInRange(volume, voxel,
x - nX, y - nY, z - (nZ + 1),
x + pX, y + pY, z - (nZ + 1));
if (distance != float.MaxValue)
{
return(distance);
}
nZ++;
// +Y Axis
distance = FindDistanceToAbnormalVoxelInRange(volume, voxel,
x - nX, y + (pY + 1), z - nZ,
x + pX, y + (pY + 1), z + pZ);
if (distance != float.MaxValue)
{
return(distance);
}
pY++;
// -Y Axis
distance = FindDistanceToAbnormalVoxelInRange(volume, voxel,
x - nX, y - (nY + 1), z - nZ,
x + pX, y - (nY + 1), z + pZ);
if (distance != float.MaxValue)
{
return(distance);
}
nY++;
// +X Axis
distance = FindDistanceToAbnormalVoxelInRange(volume, voxel,
x + (pX + 1), y - nY, z - nZ,
x + (pX + 1), y + pY, z + pZ);
if (distance != float.MaxValue)
{
return(distance);
}
pX++;
// -X Axis
distance = FindDistanceToAbnormalVoxelInRange(volume, voxel,
x - (nX + 1), y - nY, z - nZ,
x - (nX + 1), y + pY, z + pZ);
if (distance != float.MaxValue)
{
return(distance);
}
nX++;
} while (true);
}
AABBi SimulatedAnnealingFill(VoxelizationInput input, SilhouetteOcclusionValidator sov, VoxelField volume, ref Vector3i densestVoxel, byte fillByte, List <Occluder> currentOccluders)
{
AABBi current = new AABBi(densestVoxel.X, densestVoxel.Y, densestVoxel.Z, densestVoxel.X + 1, densestVoxel.Y + 1, densestVoxel.Z + 1);
AABBi next = new AABBi(0, 0, 0, 0, 0, 0);
int iteration = -1;
List <AABBi> relevantOccluders = GetRelevantOccluders(input, currentOccluders);
List <AABBi> occluders = relevantOccluders.ToList();
occluders.Add(current);
long coverage = MeasureOccluderOcclusion(sov, input, occluders);
double coolignAlpha = 0.999;
double temperature = 400.0;
double epsilon = 0.001;
Random random = new Random(1337);
int maxItterations = 1000;
long delta = 0;
while (temperature > epsilon && iteration < maxItterations)
{
iteration++;
ComputeNext(random, current, next, volume, ref densestVoxel, delta, temperature);
occluders = relevantOccluders.ToList();
occluders.Add(next);
delta = MeasureOccluderOcclusion(sov, input, occluders) - coverage;
if (delta < 0)
{
next.Clone(current);
coverage = delta + coverage;
}
else
{
double probability = random.NextDouble();
if (probability < Math.Exp(-delta / temperature))
{
next.Clone(current);
coverage = delta + coverage;
}
}
temperature *= coolignAlpha;
if (iteration % 400 == 0)
{
Console.WriteLine(coverage);
}
}
FillRange(volume,
new Vector3i(current.MinX, current.MinY, current.MinZ),
new Vector3i(current.MaxX, current.MaxY, current.MaxZ),
fillByte);
return(current);
}
public virtual VoxelizationOutput Generate(VoxelizationInput input, Action <VoxelizationProgress> progress)
{
VoxelizationProgress vp = new VoxelizationProgress();
DateTime start = DateTime.Now;
vp.Status = "Building voxel field from octree";
progress(vp);
VoxelField voxelField = new VoxelField(input.Octree);
Byte fillByte = 2;
float oldPercent = 1.0f;
float newPercent = 1.0f;
List <Occluder> occluders = new List <Occluder>();
vp.Status = "Calculating original mesh silhouette coverage";
progress(vp);
SilhouetteOcclusionValidator sov = new SilhouetteOcclusionValidator(1024, 1024);
long groundSideCoverage, groundTopCoverage;
sov.ComputeCoverage(input.OriginalMesh, input.Octree.MeshBounds, out groundSideCoverage, out groundTopCoverage);
long totalCoverage = groundSideCoverage + groundTopCoverage;
if (totalCoverage == 0)
{
totalCoverage = 1;
}
vp.Status = "Fitting boxes into mesh...";
progress(vp);
long oldOcclusion = 0;
do
{
Vector3i densestVoxel = FindHighestDensityVoxel(voxelField);
AABBi occluderBounds;
if (input.Type == OcclusionType.BoxExpansion)
{
occluderBounds = ExpandAndFillBox(voxelField, ref densestVoxel, fillByte);
}
//else if (input.Type == OcclusionType.SimulatedAnnealing)
//{
// occluderBounds = SimulatedAnnealingFill(input, sov, voxelField, ref densestVoxel, fillByte, occluders);
//}
else if (input.Type == OcclusionType.BruteForce)
{
occluderBounds = BruteForceFill(input, sov, voxelField, densestVoxel, fillByte, occluders);
}
else
{
throw new Exception("Unknown occluder generation type!");
}
List <AABBi> relevantOccluders = GetRelevantOccluders(input, occluders);
relevantOccluders.Add(occluderBounds);
long newOcclusion = MeasureOccluderOcclusion(sov, input, relevantOccluders);
Occluder occluder = new Occluder();
occluder.Bounds = occluderBounds;
occluder.DeltaOcclusion = (newOcclusion - oldOcclusion) / (double)totalCoverage;
occluders.Add(occluder);
if (occluder.DeltaOcclusion > input.MinimumOcclusion)
{
oldOcclusion = newOcclusion;
}
Debug.WriteLine("Coverage " + occluder.DeltaOcclusion);
Debug.WriteLine("Bounds (" + occluder.Bounds.MinX + "x" + occluder.Bounds.MaxX + " " + occluder.Bounds.MinY + "x" + occluder.Bounds.MaxY + " " + occluder.Bounds.MinZ + "x" + occluder.Bounds.MaxZ + ")");
oldPercent = newPercent;
newPercent = MeasureUnboxedVoxels(voxelField);
Debug.WriteLine("(" + densestVoxel.X + "," + densestVoxel.Y + "," + densestVoxel.Z + ")\tCoverage=" + ((1 - newPercent) * 100) + "%\tDelta=" + ((oldPercent - newPercent) * 100) + "%");
vp.Progress = Math.Min(((1 - newPercent) / input.MinimumVolume), 1.0f);
vp.SilhouetteCoverage = oldOcclusion / (double)totalCoverage;
vp.VolumeCoverage = 1 - newPercent;
vp.Status = String.Format("Occlusion Progress : {0:0.##}%", (100 * vp.Progress));
progress(vp);
} while (newPercent > (1 - input.MinimumVolume));
Mesh mesh = BuildMeshFromBoxes(input, GetRelevantOccluders(input, occluders));
VoxelizationOutput output = new VoxelizationOutput();
if (input.Retriangulate)
{
vp.Status = "Retriangulating occluder mesh";
progress(vp);
Mesh triangulatedMesh = MeshOptimizer.Retriangulate(input, mesh, out output.DebugLines);
if (triangulatedMesh != null)
{
mesh = triangulatedMesh;
}
}
vp.Status = "Filtering polygons";
progress(vp);
mesh = PolygonFilter.Filter(input, mesh);
vp.Status = "Generating final occlusion mesh";
progress(vp);
// Prepare the output
output.Octree = input.Octree;
output.TimeTaken = DateTime.Now - start;
output.VolumeCoverage = 1 - newPercent;
output.SilhouetteCoverage = oldOcclusion / (double)totalCoverage;
output.OccluderMesh = new RenderableMesh(mesh, true);
vp.Status = "Cleanup...";
progress(vp);
sov.Dispose();
return(output);
}
AABBi BruteForceFill(VoxelizationInput input, SilhouetteOcclusionValidator sov, VoxelField voxelField, Vector3i densestVoxel, byte fillByte, List <Occluder> currentOccluders)
{
Object syncroot = new Object();
Int64 largestVolume = 1;
AABBi largestOccluder = new AABBi(densestVoxel.X, densestVoxel.Y, densestVoxel.Z, densestVoxel.X + 1, densestVoxel.Y + 1, densestVoxel.Z + 1);
int MaxTopOccluders = 2000;
List <AABBi> bestOccluders = new List <AABBi>(MaxTopOccluders);
Parallel.For(densestVoxel.Z + 1, voxelField.VoxelSize.Z, max_z =>
{
for (Int32 min_z = densestVoxel.Z; min_z >= 0; --min_z)
{
for (Int32 max_y = densestVoxel.Y + 1; max_y < voxelField.VoxelSize.Y; ++max_y)
{
for (Int32 min_y = densestVoxel.Y; min_y >= 0; --min_y)
{
for (Int32 max_x = densestVoxel.X + 1; max_x < voxelField.VoxelSize.X; ++max_x)
{
for (Int32 min_x = densestVoxel.X; min_x >= 0; --min_x)
{
Int32 dx = max_x - min_x;
Int32 dy = max_y - min_y;
Int32 dz = max_z - min_z;
Int64 volume = dx * dy * dz;
if (TestRangeForFreeSpace(voxelField, new AABBi(min_x, min_y, min_z, max_x, max_y, max_z)))
{
lock (syncroot)
{
if (volume > largestVolume)
{
largestVolume = volume;
largestOccluder = new AABBi(min_x, min_y, min_z, max_x, max_y, max_z);
if (bestOccluders.Count >= MaxTopOccluders)
{
bestOccluders.RemoveAt(MaxTopOccluders - 1);
}
bestOccluders.Insert(0, largestOccluder);
}
}
}
else
{
// if we can't expand outward any further there's no point in checking more.
break;
}
}
}
}
}
}
Debug.WriteLine("Checked " + max_z);
});
List <AABBi> relevantOccluders = GetRelevantOccluders(input, currentOccluders);
long bestCoverage = 0;
AABBi bestCoverageVolume = largestOccluder;
foreach (AABBi occluder in bestOccluders)
{
List <AABBi> tempOccluders = relevantOccluders.ToList();
tempOccluders.Add(occluder);
long coverage = MeasureOccluderOcclusion(sov, input, tempOccluders);
if (coverage > bestCoverage)
{
bestCoverage = coverage;
bestCoverageVolume = occluder;
}
}
FillRange(voxelField, bestCoverageVolume, fillByte);
return(bestCoverageVolume);
}
