public GridAccelerator(IEnumerable<Primitive> primitives, bool refineImmediately)
{
// Initialize _primitives_ with primitives for grid
_primitives = refineImmediately
? primitives.SelectMany(prim => prim.FullyRefine()).ToArray()
: primitives.ToArray();
// Compute bounds and choose grid resolution
_bounds = BBox.Empty;
for (var i = 0; i < _primitives.Length; ++i)
_bounds = BBox.Union(_bounds, _primitives[i].WorldBound);
Vector delta = _bounds.Max - _bounds.Min;
// Find _voxelsPerUnitDist_ for grid
int maxAxis = _bounds.MaximumExtent();
float invMaxWidth = 1.0f / delta[maxAxis];
Debug.Assert(invMaxWidth > 0.0f);
float cubeRoot = 3.0f * MathUtility.Pow(_primitives.Length, 1.0f / 3.0f);
float voxelsPerUnitDist = cubeRoot * invMaxWidth;
_numVoxels = new int[3];
for (int axis = 0; axis < 3; ++axis)
{
_numVoxels[axis] = MathUtility.Round(delta[axis] * voxelsPerUnitDist);
_numVoxels[axis] = MathUtility.Clamp(_numVoxels[axis], 1, 64);
}
// Compute voxel widths and allocate voxels
for (int axis = 0; axis < 3; ++axis)
{
_width[axis] = delta[axis] / _numVoxels[axis];
_inverseWidth[axis] = (_width[axis] == 0.0f) ? 0.0f : 1.0f / _width[axis];
}
int nv = _numVoxels[0] * _numVoxels[1] * _numVoxels[2];
_voxels = new GridVoxel[nv];
// Add primitives to grid voxels
for (var i = 0; i < _primitives.Length; ++i)
{
// Find voxel extent of primitive
BBox pb = _primitives[i].WorldBound;
int[] vmin = new int[3], vmax = new int[3];
for (int axis = 0; axis < 3; ++axis)
{
vmin[axis] = PosToVoxel(ref pb.Min, axis);
vmax[axis] = PosToVoxel(ref pb.Max, axis);
}
// Add primitive to overlapping voxels
for (int z = vmin[2]; z <= vmax[2]; ++z)
for (int y = vmin[1]; y <= vmax[1]; ++y)
for (int x = vmin[0]; x <= vmax[0]; ++x)
{
int o = Offset(x, y, z);
if (_voxels[o] == null)
{
// Allocate new voxel and store primitive in it
_voxels[o] = new GridVoxel(_primitives[i]);
}
else
{
// Add primitive to already-allocated voxel
_voxels[o].AddPrimitive(_primitives[i]);
}
}
}
}
public GridAccelerator(IEnumerable <Primitive> primitives, bool refineImmediately)
{
// Initialize _primitives_ with primitives for grid
_primitives = refineImmediately
? primitives.SelectMany(prim => prim.FullyRefine()).ToArray()
: primitives.ToArray();
// Compute bounds and choose grid resolution
_bounds = BBox.Empty;
for (var i = 0; i < _primitives.Length; ++i)
{
_bounds = BBox.Union(_bounds, _primitives[i].WorldBound);
}
Vector delta = _bounds.Max - _bounds.Min;
// Find _voxelsPerUnitDist_ for grid
int maxAxis = _bounds.MaximumExtent();
float invMaxWidth = 1.0f / delta[maxAxis];
Debug.Assert(invMaxWidth > 0.0f);
float cubeRoot = 3.0f * MathUtility.Pow(_primitives.Length, 1.0f / 3.0f);
float voxelsPerUnitDist = cubeRoot * invMaxWidth;
_numVoxels = new int[3];
for (int axis = 0; axis < 3; ++axis)
{
_numVoxels[axis] = MathUtility.Round(delta[axis] * voxelsPerUnitDist);
_numVoxels[axis] = MathUtility.Clamp(_numVoxels[axis], 1, 64);
}
// Compute voxel widths and allocate voxels
for (int axis = 0; axis < 3; ++axis)
{
_width[axis] = delta[axis] / _numVoxels[axis];
_inverseWidth[axis] = (_width[axis] == 0.0f) ? 0.0f : 1.0f / _width[axis];
}
int nv = _numVoxels[0] * _numVoxels[1] * _numVoxels[2];
_voxels = new GridVoxel[nv];
// Add primitives to grid voxels
for (var i = 0; i < _primitives.Length; ++i)
{
// Find voxel extent of primitive
BBox pb = _primitives[i].WorldBound;
int[] vmin = new int[3], vmax = new int[3];
for (int axis = 0; axis < 3; ++axis)
{
vmin[axis] = PosToVoxel(ref pb.Min, axis);
vmax[axis] = PosToVoxel(ref pb.Max, axis);
}
// Add primitive to overlapping voxels
for (int z = vmin[2]; z <= vmax[2]; ++z)
{
for (int y = vmin[1]; y <= vmax[1]; ++y)
{
for (int x = vmin[0]; x <= vmax[0]; ++x)
{
int o = Offset(x, y, z);
if (_voxels[o] == null)
{
// Allocate new voxel and store primitive in it
_voxels[o] = new GridVoxel(_primitives[i]);
}
else
{
// Add primitive to already-allocated voxel
_voxels[o].AddPrimitive(_primitives[i]);
}
}
}
}
}
}