// List of BVHPrimitive infos including each triangle of the object
// Start/end/total nodes for recursive split of the list
private BVHBuildNode BuildRecursiveBVH(ref List <BVHPrimitiveInfo> primitiveInfos,
int start, int end, ref int totalNodes)
{
BVHBuildNode node = new BVHBuildNode();
totalNodes++;
Bounds3 bounds = new Bounds3();
bounds.pMin = Vector3.positiveInfinity;
bounds.pMax = Vector3.negativeInfinity;
// Calculate bounds of the parent BVH node from its children
for (int i = start; i < end; i++)
{
bounds = bounds.Union(primitiveInfos[i].bounds);
}
int nPrimitives = end - start;
// Create leaf
if (nPrimitives == 1)
{
node.InitLeaf(primitiveInfos[start].triangleNo, bounds);
return(node);
}
else
{
Bounds3 centroidBounds = new Bounds3();
centroidBounds.pMin = Vector3.positiveInfinity;
centroidBounds.pMax = Vector3.negativeInfinity;
for (int i = start; i < end; i++)
{
centroidBounds = centroidBounds.Union(primitiveInfos[i].center);
}
int dim = centroidBounds.MaximumExtend();
int mid = (start + end) / 2;
// Order Primitives in axis 'dim' and split the list into 2 equal sized lists
EqualCounts(ref primitiveInfos, dim, start, end);
node.InitInterior(dim,
BuildRecursiveBVH(ref primitiveInfos, start, mid, ref totalNodes),
BuildRecursiveBVH(ref primitiveInfos, mid, end, ref totalNodes)
);
return(node);
}
}
public PrimitiveList(IEnumerable <Primitive> primitives)
{
Primitives = new List <Primitive>(primitives);
// Cache the world space bounds
if (Primitives.Any())
{
worldBounds = Primitives.First().WorldBounds;
foreach (var p in Primitives.Skip(1))
{
worldBounds = worldBounds.Union(p.WorldBounds);
}
}
}
public void SetTrigles(TrigleFace[] trigles)
{
this.trigles = trigles;
if (trigles != null && trigles.Length > 0)
{
Bounds3 bounds = trigles[0].BoundBox;
foreach (var item in trigles)
{
bounds = Bounds3.Union(bounds, item.BoundBox);
//item.material = _material;
}
this.BoundBox = bounds;
}
else
{
this.BoundBox = new Bounds3();
}
CenterPoint = (BoundBox.pMin + BoundBox.pMax) * 0.5f;
BVH = BVH.Build(trigles.AsSpan());
}
private BVHBuildNode RecursiveBuild(List <PrimitiveInfo> primitiveInfos, int start, int end, ref int nodeCount, ref List <Primitive> orderedPrimitives)
{
var node = new BVHBuildNode();
++nodeCount;
// Compute the bounds of all the primitives below this node
Bounds3 <float> bounds = new Bounds3 <float>();
for (var i = start; i < end; ++i)
{
bounds = bounds.Union(primitiveInfos[i].Bounds);
}
var primitiveCount = end - start;
// Create leaf node
if (primitiveCount == 1)
{
var firstPrimitiveOffset = orderedPrimitives.Count();
for (var i = start; i < end; ++i)
{
orderedPrimitives.Add(allPrimitives[primitiveInfos[i].Index]);
}
node.InitLeaf(firstPrimitiveOffset, primitiveCount, bounds);
}
// Create interior node
else
{
// Choose the axis to split (with the longest extent)
var centroidBounds = new Bounds3 <float>();
for (var i = start; i < end; ++i)
{
centroidBounds = centroidBounds.Union(primitiveInfos[i].Centroid);
}
var dim = centroidBounds.MaximumExtent();
var mid = (start + end) / 2;
// Juste create a leaf node if the bounds have zero volume
// (all centroids are at the same position)
if (centroidBounds.Max[dim] == centroidBounds.Min[dim])
{
var firstPrimitiveOffset = orderedPrimitives.Count();
for (var i = start; i < end; ++i)
{
orderedPrimitives.Add(allPrimitives[primitiveInfos[i].Index]);
}
node.InitLeaf(firstPrimitiveOffset, primitiveCount, bounds);
}
else
{
// Sort primitives in the current range along the split dimension
var orderedRange = primitiveInfos
.GetRange(start, end - start)
.OrderBy(p => p.Centroid[dim]);
primitiveInfos = primitiveInfos.GetRange(0, start)
.Concat(orderedRange)
.Concat(primitiveInfos.GetRange(end, primitiveInfos.Count - end))
.ToList();
// Recursively split the rest of the tree
node.InitInterior(
dim,
RecursiveBuild(primitiveInfos, start, mid, ref nodeCount, ref orderedPrimitives),
RecursiveBuild(primitiveInfos, mid, end, ref nodeCount, ref orderedPrimitives));
}
}
return(node);
}
