class UniformGrid(Aggregate):
def __init__(self, primitives: [Primitive], refine_immediately: bool):
super().__init__()
self.voxels = []
self.bounds = BoundingBox()
self.width = Vector3d()
self.inv_width = Vector3d()
self.nVoxels = [int] * 3
self.primitives = []
# Initialize _primitives_ with primitives for grid
if refine_immediately:
for p in primitives:
p.get_fully_refine(self.primitives)
else:
self.primitives = primitives
# Compute bounds and choose grid resolution
for p in self.primitives:
self.bounds = BoundingBox.get_union_bbox(self.bounds, p.get_world_bound())
delta = self.bounds.point_max - self.bounds.point_min
#Find _voxelsPerUnitDist_ for grid
maxAxis = self.bounds.get_maximum_extent()
invMaxWidth = 1.0 / delta[maxAxis]
assert (invMaxWidth > 0.0)
cubeRoot = 3.0 * pow(float(len(self.primitives)), 1.0 / 3.0)
voxelsPerUnitDist = cubeRoot * invMaxWidth
for axis in range(3):
self.nVoxels[axis] = int(math.floor(delta[axis] * voxelsPerUnitDist))
self.nVoxels[axis] = maths.tools.get_clamp(self.nVoxels[axis], 1, 64)
# Compute voxel widths and allocate voxels
for axis in range(3):
self.width[axis] = delta[axis] / self.nVoxels[axis]
if self.width[axis] == 0.0:
self.inv_width[axis] = 0.0
else:
self.inv_width[axis] = 1.0 / self.width[axis]
nv = self.nVoxels[0] * self.nVoxels[1] * self.nVoxels[2]
self.voxels = [None] * nv
#Add primitives to grid voxels
for p in self.primitives:
# Find voxel extent of primitive
pb = p.get_world_bound()
vmin = [int] * 3
vmax = [int] * 3
for axis in range(3):
vmin[axis] = self.get_pos_to_voxel(pb.point_min, axis)
vmax[axis] = self.get_pos_to_voxel(pb.point_max, axis)
# Add primitive to overlapping voxels
for z in range(vmin[2], vmax[2]+1):
for y in range(vmin[1], vmax[1]+1):
for x in range(vmin[0], vmax[0]+1):
o = self.get_offset(x, y, z)
if self.voxels[o] is None:
# Allocate new voxel and store primitive in it
self.voxels[o] = Voxel(p)
else:
# Add primitive to already-allocated voxel
self.voxels[o].add_primitive(p)
def get_world_bound(self):
return self.bounds
def get_can_intersect(self):
return True
def get_is_intersected(self, ray: Ray) -> bool:
# Check ray against overall grid bounds
if self.bounds.get_is_point_inside(ray.get_at(ray.min_t)):
rayT = ray.min_t
else:
rayT, tmp = self.bounds.get_intersect(ray)
if rayT is None:
return False
gridIntersect = ray.get_at(rayT)
# Set up 3D DDA for ray
NextCrossingT = [float] * 3
DeltaT = [float] * 3
Step = [int] * 3
Out = [int] * 3
Pos = [int] * 3
for axis in range(3):
# Compute current voxel for axis
Pos[axis] = self.get_pos_to_voxel(gridIntersect, axis)
if ray.direction[axis] >= 0:
# Handle ray with positive direction for voxel stepping
NextCrossingT[axis] = rayT + (self.get_voxel_to_pos(Pos[axis] + 1, axis) - gridIntersect[axis]) / \
ray.direction[axis]
DeltaT[axis] = self.width[axis] / ray.direction[axis]
Step[axis] = 1
Out[axis] = self.nVoxels[axis]
else:
# Handle ray with negative direction for voxel stepping
NextCrossingT[axis] = rayT + (self.get_voxel_to_pos(Pos[axis], axis) - gridIntersect[axis]) / \
ray.direction[axis]
DeltaT[axis] = -self.width[axis] / ray.direction[axis]
Step[axis] = -1
Out[axis] = -1
#Walk grid for shadow ray
while True:
o = self.get_offset(Pos[0], Pos[1], Pos[2])
voxel = self.voxels[o]
if voxel is not None:
if voxel.get_is_intersected(ray):
return True
# Advance to next voxel
# Find _stepAxis_ for stepping to next voxel
bits = ((NextCrossingT[0] < NextCrossingT[1]) << 2) + ((NextCrossingT[0] < NextCrossingT[2]) << 1) + (
(NextCrossingT[1] < NextCrossingT[2]))
cmpToAxis = [2, 1, 2, 1, 2, 2, 0, 0]
stepAxis = cmpToAxis[bits]
if ray.max_t < NextCrossingT[stepAxis]:
break
Pos[stepAxis] += Step[stepAxis]
if Pos[stepAxis] == Out[stepAxis]:
break
NextCrossingT[stepAxis] += DeltaT[stepAxis]
return False
def get_intersection(self, ray: Ray, intersection: Intersection) -> bool:
# Check ray against overall grid bounds
if self.bounds.get_is_point_inside(ray.get_at(ray.min_t)):
rayT = ray.min_t
else:
rayT, tmp = self.bounds.get_intersect(ray)
if rayT is None:
return False
gridIntersect = ray.get_at(rayT)
# Set up 3D DDA for ray
NextCrossingT = [float] * 3
DeltaT = [float] * 3
Step = [int] * 3
Out = [int] * 3
Pos = [int] * 3
for axis in range(3):
# Compute current voxel for axis
Pos[axis] = self.get_pos_to_voxel(gridIntersect, axis)
if ray.direction[axis] >= 0:
# Handle ray with positive direction for voxel stepping
NextCrossingT[axis] = rayT + (self.get_voxel_to_pos(Pos[axis] + 1, axis) - gridIntersect[axis]) / \
ray.direction[axis]
DeltaT[axis] = self.width[axis] / ray.direction[axis]
Step[axis] = 1
Out[axis] = self.nVoxels[axis]
else:
# Handle ray with negative direction for voxel stepping
NextCrossingT[axis] = rayT + (self.get_voxel_to_pos(Pos[axis], axis) - gridIntersect[axis]) / \
ray.direction[axis]
DeltaT[axis] = -self.width[axis] / ray.direction[axis]
Step[axis] = -1
Out[axis] = -1
# Walk ray through voxel grid
hitSomething = False
while True:
# Check for intersection in current voxel and advance to next
voxel = self.voxels[self.get_offset(Pos[0], Pos[1], Pos[2])]
if voxel is not None:
hitSomething |= voxel.get_intersection(ray, intersection)
# Advance to next voxel
# Find _stepAxis_ for stepping to next voxel
bits = ((NextCrossingT[0] < NextCrossingT[1]) << 2) + ((NextCrossingT[0] < NextCrossingT[2]) << 1) + (
(NextCrossingT[1] < NextCrossingT[2]))
cmpToAxis = [2, 1, 2, 1, 2, 2, 0, 0]
stepAxis = cmpToAxis[bits]
if ray.max_t < NextCrossingT[stepAxis]:
break
Pos[stepAxis] += Step[stepAxis]
if Pos[stepAxis] == Out[stepAxis]:
break
NextCrossingT[stepAxis] += DeltaT[stepAxis]
return hitSomething
def get_pos_to_voxel(self, point: Point3d, axis: int) -> int:
v = int((point[axis] - self.bounds.point_min[axis]) * self.inv_width[axis])
return get_clamp(v, 0, self.nVoxels[axis] - 1)
def get_voxel_to_pos(self, p: int, axis: int) -> float:
return self.bounds.point_min[axis] + p * self.width[axis]
def get_offset(self, x: int, y: int, z: int) -> int:
return z * self.nVoxels[0] * self.nVoxels[1] + y * self.nVoxels[0] + x