public override bool TryToIntersect(Ray ray, ref Intersection intersection)
{
float rayT = 0, t = 0;
if (_bbox.Inside(ray.PointAtTime(ray.Start)))
{
rayT = ray.Start;
}
else if (!_bbox.IntersectP(ray, ref rayT, ref t))
{
return(false);
}
var gridIntersect = ray.PointAtTime(rayT);
float[] nextCrossingT = new float[3], deltaT = new float[3];
int[] step = new int[3], _out = new int[3], pos = new int[3];
for (var i = 0; i < 3; i++)
{
pos[i] = PosToVoxel(gridIntersect, i);
if (ray.Direction[i] >= 0)
{
nextCrossingT[i] = rayT + (VoxelToPos(pos[i] + 1, i) - gridIntersect[i]) / ray.Direction[i];
deltaT[i] = _width[i] / ray.Direction[i];
step[i] = 1;
_out[i] = _nVoxels[i];
}
else
{
nextCrossingT[i] = rayT + (VoxelToPos(pos[i], i) - gridIntersect[i]) / ray.Direction[i];
deltaT[i] = -_width[i] / ray.Direction[i];
step[i] = -1;
_out[i] = -1;
}
}
var hitSomething = false;
for (;;)
{
var voxel = _voxels[Offset(pos[0], pos[1], pos[2])];
if (voxel != null)
{
hitSomething |= voxel.TryToIntersect(ray, ref intersection);
}
var bits = (((nextCrossingT[0] < nextCrossingT[1]) ? 1 : 0) << 2) +
(((nextCrossingT[0] < nextCrossingT[2]) ? 1 : 0) << 1) +
(((nextCrossingT[1] < nextCrossingT[2]) ? 1 : 0));
var stepAxis = _cmpToAxis[bits];
if (ray.End < nextCrossingT[stepAxis])
{
break;
}
pos[stepAxis] += step[stepAxis];
if (pos[stepAxis] == _out[stepAxis])
{
break;
}
nextCrossingT[stepAxis] += deltaT[stepAxis];
}
return(hitSomething);
}
