// build tree of boxes as sequential array
void build_sequential(DCurve3 curve)
{
int NV = curve.VertexCount;
int N = NV;
int boxCount = 0;
layers = 0;
layer_counts = new List <int>();
// count how many boxes in each layer, building up from initial segments
int bi = 0;
while (N > 1)
{
int layer_boxes = (N / 2) + (N % 2 == 0 ? 0 : 1);
boxCount += layer_boxes;
N = layer_boxes;
layer_counts.Add(layer_boxes);
bi += layer_boxes;
layers++;
}
boxes = new Box3d[boxCount];
bi = 0;
// make first layer
for (int si = 0; si < NV; si += 2)
{
Vector3d v1 = curve[(si + 1) % NV];
Segment3d seg1 = new Segment3d(curve[si], v1);
Box3d box = new Box3d(seg1);
if (si < NV - 1)
{
Segment3d seg2 = new Segment3d(v1, curve[(si + 2) % NV]);
Box3d box2 = new Box3d(seg2);
box = Box3d.Merge(ref box, ref box2);
}
boxes[bi++] = box;
}
// repeatedly build layers until we hit a single box
N = bi;
int prev_layer_start = 0;
bool done = false;
while (done == false)
{
int layer_start = bi;
for (int k = 0; k < N; k += 2)
{
Box3d mbox = Box3d.Merge(ref boxes[prev_layer_start + k], ref boxes[prev_layer_start + k + 1]);
boxes[bi++] = mbox;
}
N = (N / 2) + (N % 2 == 0 ? 0 : 1);
prev_layer_start = layer_start;
if (N == 1)
{
done = true;
}
}
}
// ported from WildMagic5 Wm5ContBox3.cpp::MergeBoxes
public static Box3d Merge(ref Box3d box0, ref Box3d box1)
{
// Construct a box that contains the input boxes.
Box3d box = new Box3d();
// The first guess at the box center. This value will be updated later
// after the input box vertices are projected onto axes determined by an
// average of box axes.
box.Center = 0.5 * (box0.Center + box1.Center);
// A box's axes, when viewed as the columns of a matrix, form a rotation
// matrix. The input box axes are converted to quaternions. The average
// quaternion is computed, then normalized to unit length. The result is
// the slerp of the two input quaternions with t-value of 1/2. The result
// is converted back to a rotation matrix and its columns are selected as
// the merged box axes.
Quaterniond q0 = new Quaterniond(), q1 = new Quaterniond();
Matrix3d rot0 = new Matrix3d(ref box0.AxisX, ref box0.AxisY, ref box0.AxisZ, false);
q0.SetFromRotationMatrix(ref rot0);
Matrix3d rot1 = new Matrix3d(ref box1.AxisX, ref box1.AxisY, ref box1.AxisZ, false);
q1.SetFromRotationMatrix(ref rot1);
if (q0.Dot(q1) < 0)
{
q1 = -q1;
}
Quaterniond q = q0 + q1;
double invLength = 1.0 / Math.Sqrt(q.Dot(q));
q = q * invLength;
Matrix3d q_mat = q.ToRotationMatrix();
box.AxisX = q_mat.Column(0); box.AxisY = q_mat.Column(1); box.AxisZ = q_mat.Column(2); //q.ToRotationMatrix(box.Axis);
// Project the input box vertices onto the merged-box axes. Each axis
// D[i] containing the current center C has a minimum projected value
// min[i] and a maximum projected value max[i]. The corresponding end
// points on the axes are C+min[i]*D[i] and C+max[i]*D[i]. The point C
// is not necessarily the midpoint for any of the intervals. The actual
// box center will be adjusted from C to a point C' that is the midpoint
// of each interval,
// C' = C + sum_{i=0}^2 0.5*(min[i]+max[i])*D[i]
// The box extents are
// e[i] = 0.5*(max[i]-min[i])
int i, j;
double dot;
Vector3d[] vertex = new Vector3d[8];
Vector3d pmin = Vector3d.Zero;
Vector3d pmax = Vector3d.Zero;
box0.ComputeVertices(vertex);
for (i = 0; i < 8; ++i)
{
Vector3d diff = vertex[i] - box.Center;
for (j = 0; j < 3; ++j)
{
dot = box.Axis(j).Dot(ref diff);
if (dot > pmax[j])
{
pmax[j] = dot;
}
else if (dot < pmin[j])
{
pmin[j] = dot;
}
}
}
box1.ComputeVertices(vertex);
for (i = 0; i < 8; ++i)
{
Vector3d diff = vertex[i] - box.Center;
for (j = 0; j < 3; ++j)
{
dot = box.Axis(j).Dot(ref diff);
if (dot > pmax[j])
{
pmax[j] = dot;
}
else if (dot < pmin[j])
{
pmin[j] = dot;
}
}
}
// [min,max] is the axis-aligned box in the coordinate system of the
// merged box axes. Update the current box center to be the center of
// the new box. Compute the extents based on the new center.
for (j = 0; j < 3; ++j)
{
box.Center += (0.5 * (pmax[j] + pmin[j])) * box.Axis(j);
box.Extent[j] = 0.5 * (pmax[j] - pmin[j]);
}
return(box);
}
// solidBox == false means fully contained segment does not intersect
public IntrSegment3Box3(Segment3d s, Box3d b, bool solidBox)
{
segment = s; box = b; this.solid = solidBox;
}
/// <summary>
/// test if ray intersects box.
/// expandExtents allows you to scale box for hit-testing purposes.
/// </summary>
public static bool Intersects(ref Ray3d ray, ref Box3d box, double expandExtents = 0)
{
Vector3d WdU = Vector3d.Zero;
Vector3d AWdU = Vector3d.Zero;
Vector3d DdU = Vector3d.Zero;
Vector3d ADdU = Vector3d.Zero;
Vector3d AWxDdU = Vector3d.Zero;
double RHS;
Vector3d diff = ray.Origin - box.Center;
Vector3d extent = box.Extent + expandExtents;
WdU[0] = ray.Direction.Dot(ref box.AxisX);
AWdU[0] = Math.Abs(WdU[0]);
DdU[0] = diff.Dot(ref box.AxisX);
ADdU[0] = Math.Abs(DdU[0]);
if (ADdU[0] > extent.x && DdU[0] * WdU[0] >= (double)0)
{
return(false);
}
WdU[1] = ray.Direction.Dot(ref box.AxisY);
AWdU[1] = Math.Abs(WdU[1]);
DdU[1] = diff.Dot(ref box.AxisY);
ADdU[1] = Math.Abs(DdU[1]);
if (ADdU[1] > extent.y && DdU[1] * WdU[1] >= (double)0)
{
return(false);
}
WdU[2] = ray.Direction.Dot(ref box.AxisZ);
AWdU[2] = Math.Abs(WdU[2]);
DdU[2] = diff.Dot(ref box.AxisZ);
ADdU[2] = Math.Abs(DdU[2]);
if (ADdU[2] > extent.z && DdU[2] * WdU[2] >= (double)0)
{
return(false);
}
Vector3d WxD = ray.Direction.Cross(diff);
AWxDdU[0] = Math.Abs(WxD.Dot(ref box.AxisX));
RHS = extent.y * AWdU[2] + extent.z * AWdU[1];
if (AWxDdU[0] > RHS)
{
return(false);
}
AWxDdU[1] = Math.Abs(WxD.Dot(ref box.AxisY));
RHS = extent.x * AWdU[2] + extent.z * AWdU[0];
if (AWxDdU[1] > RHS)
{
return(false);
}
AWxDdU[2] = Math.Abs(WxD.Dot(ref box.AxisZ));
RHS = extent.x * AWdU[1] + extent.y * AWdU[0];
if (AWxDdU[2] > RHS)
{
return(false);
}
return(true);
}
public IntrRay3Box3(Ray3d r, Box3d b)
{
ray = r; box = b;
}
public IntrLine3Box3(Line3d l, Box3d b)
{
line = l; box = b;
}
// build tree of boxes as sequential array
void build_sequential(DCurve3 curve)
{
int NV = curve.VertexCount;
int N = (curve.Closed) ? NV : NV - 1;
int boxCount = 0;
layers = 0;
layer_counts = new List <int>();
// count how many boxes in each layer, building up from initial segments
int bi = 0;
while (N > 1)
{
int layer_boxes = (N / 2) + (N % 2 == 0 ? 0 : 1);
boxCount += layer_boxes;
N = layer_boxes;
layer_counts.Add(layer_boxes);
bi += layer_boxes;
layers++;
}
// [RMS] this case happens if N = 1, previous loop is skipped and we have to
// hardcode initialization to this redundant box
if (layers == 0)
{
layers = 1;
boxCount = 1;
layer_counts = new List <int>()
{
1
};
}
boxes = new Box3d[boxCount];
bi = 0;
// make first layer
int NStop = (curve.Closed) ? NV : NV - 1;
for (int si = 0; si < NStop; si += 2)
{
Vector3d v1 = curve[(si + 1) % NV];
Segment3d seg1 = new Segment3d(curve[si], v1);
Box3d box = new Box3d(seg1);
if (si < NV - 1)
{
Segment3d seg2 = new Segment3d(v1, curve[(si + 2) % NV]);
Box3d box2 = new Box3d(seg2);
box = Box3d.Merge(ref box, ref box2);
}
boxes[bi++] = box;
}
// repeatedly build layers until we hit a single box
N = bi;
if (N == 1)
{
return;
}
int prev_layer_start = 0;
bool done = false;
while (done == false)
{
int layer_start = bi;
for (int k = 0; k < N; k += 2)
{
Box3d mbox = Box3d.Merge(ref boxes[prev_layer_start + k], ref boxes[prev_layer_start + k + 1]);
boxes[bi++] = mbox;
}
N = (N / 2) + (N % 2 == 0 ? 0 : 1);
prev_layer_start = layer_start;
if (N == 1)
{
done = true;
}
}
}
