def intersect(self, ray, intersection):
"""Compute an intersection."""
w2p = self.world_to_primitive.interpolate(ray.time)
ray_primitive = w2p(ray)
intersection = Intersection()
if not self.primitive.intersect(ray_primitive, intersection):
return False
ray.maxt = ray_primitive.maxt
intersection.primitive_id = self.primitive_id
if not w2p.is_identity():
# Compute world-to-object transformation for instance
intersection.world_to_object = intersection.world_to_object * w2p
intersection.object_to_world = inverse(
intersection.world_to_object)
p2w = inverse(w2p)
# Transform instance's differential geometry to world space
intersection.dg.p = p2w(intersection.dg.p)
intersection.dg.nn = normalize(p2w(intersection.dg.nn))
intersection.dg.dpdu = p2w(intersection.dg.dp_du)
intersection.dg.dpdv = p2w(intersection.dg.dp_dv)
intersection.dg.dndu = p2w(intersection.dg.dn_du)
intersection.dg.dndv = p2w(intersection.dg.dn_dv)
return True
def from_intersection(cls, p, dp_du, dp_dv, dn_du, dn_dv, uu, vv, shape=None):
"""Construct a DifferentialGeometry instance.
Arguments:
p : Point
dp_du : Vector
dp_dv : Vector
dn_du : Normal
dn_dv : Normal
uu : float
vv : float
shape : optional Shape
"""
# call default constructor
diff_geom = cls()
diff_geom.p = p
diff_geom.dp_du = dp_du
diff_geom.dp_dv = dp_dv
diff_geom.dn_du = dn_du
diff_geom.dn_dv = dn_dv
diff_geom.nn = Normal.from_vector(normalize(cross(dp_du, dp_dv)))
diff_geom.u = uu
diff_geom.v = vv
diff_geom.shape = shape
if shape and \
(shape.reverse_orientation ^ shape.transform_swap_handedness):
diff_geom.nn *= -1.0
return diff_geom
def from_intersection(cls,
p,
dp_du,
dp_dv,
dn_du,
dn_dv,
uu,
vv,
shape=None):
"""Construct a DifferentialGeometry instance.
Arguments:
p : Point
dp_du : Vector
dp_dv : Vector
dn_du : Normal
dn_dv : Normal
uu : float
vv : float
shape : optional Shape
"""
# call default constructor
diff_geom = cls()
diff_geom.p = p
diff_geom.dp_du = dp_du
diff_geom.dp_dv = dp_dv
diff_geom.dn_du = dn_du
diff_geom.dn_dv = dn_dv
diff_geom.nn = Normal.from_vector(normalize(cross(dp_du, dp_dv)))
diff_geom.u = uu
diff_geom.v = vv
diff_geom.shape = shape
if shape and \
(shape.reverse_orientation ^ shape.transform_swap_handedness):
diff_geom.nn *= -1.0
return diff_geom
def intersect(self, ray, intersection):
"""Compute an intersection."""
w2p = self.world_to_primitive.interpolate(ray.time)
ray_primitive = w2p(ray)
intersection = Intersection()
if not self.primitive.intersect(ray_primitive, intersection):
return False
ray.maxt = ray_primitive.maxt
intersection.primitive_id = self.primitive_id
if not w2p.is_identity():
# Compute world-to-object transformation for instance
intersection.world_to_object = intersection.world_to_object * w2p
intersection.object_to_world = inverse(intersection.world_to_object)
p2w = inverse(w2p)
# Transform instance's differential geometry to world space
intersection.dg.p = p2w(intersection.dg.p)
intersection.dg.nn = normalize(p2w(intersection.dg.nn))
intersection.dg.dpdu = p2w(intersection.dg.dp_du)
intersection.dg.dpdv = p2w(intersection.dg.dp_dv)
intersection.dg.dndu = p2w(intersection.dg.dn_du)
intersection.dg.dndv = p2w(intersection.dg.dn_dv)
return True
