def __init__(self, primitives, refine_immediately):
"""Default constructor for GridAccel."""
# initialize self.primitives with primitives for grid
if refine_immediately:
self.primitives = []
for primitive in primitives:
primitive.fully_refine(self.primitives)
else:
self.primitives = list(primitives)
# compute bounds and choose grid resolution
self.bounds = BBox()
for primitive in self.primitives:
self.bounds = union(self.bounds, primitive.world_bound())
delta = self.bounds.p_max - self.bounds.p_min
# find voxels_per_unit_dist for grid
max_axis = self.bounds.maximum_extent()
inv_max_width = 1.0 / delta[max_axis]
cube_root = 3.0 * pow(len(self.primitives), 1.0 / 3.0)
voxels_per_unit_dist = cube_root * inv_max_width
self.n_voxels = []
for axis in range(3):
self.n_voxels.append(
clamp(round_to_int(delta[axis] * voxels_per_unit_dist), 1, 64))
# compute voxel widths and allocate voxels
self.width = Vector()
self.inv_width = Vector()
for axis in range(3):
self.width[axis] = delta[axis] / self.n_voxels[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.n_voxels[0] * self.n_voxels[1] * self.n_voxels[2]
# array of voxels, initialized at None
self.voxels = [None] * nv
# add primitives to grid voxels
for primitive in self.primitives:
# find voxel extent of primitive
primitive_bound = primitive.world_bound()
v_min = []
v_max = []
for axis in range(3):
v_min.append(self._pos_to_voxel(primitive_bound.p_min, axis))
v_max.append(self._pos_to_voxel(primitive_bound.p_max, axis))
# add primitive to overlapping voxels
for z in range(v_min[2], v_max[2] + 1):
for y in range(v_min[1], v_max[1] + 1):
for x in range(v_min[0], v_max[0] + 1):
index = self._offset(x, y, z)
if self.voxels[index] is None:
self.voxels[index] = Voxel(primitive)
else:
self.voxels[index].add_primitive(primitive)
# create reader-writer mutex for grid
self.rw_lock = DummyRWLock()
