def proj_transform_vec_clip(vec, M):
vecw = nx.matrixmultiply(M, vec)
w = vecw[3]
# clip here..
txs, tys, tzs = vecw[0] / w, vecw[1] / w, vecw[2] / w
tis = (vecw[0] >= 0) * (vecw[0] <= 1) * (vecw[1] >= 0) * (vecw[1] <= 1)
if nx.sometrue(tis):
tis = vecw[1] < 1
return txs, tys, tzs, tis
def makeMappingArray(N, data):
"""Create an N-element 1-d lookup table
data represented by a list of x,y0,y1 mapping correspondences.
Each element in this list represents how a value between 0 and 1
(inclusive) represented by x is mapped to a corresponding value
between 0 and 1 (inclusive). The two values of y are to allow
for discontinuous mapping functions (say as might be found in a
sawtooth) where y0 represents the value of y for values of x
<= to that given, and y1 is the value to be used for x > than
that given). The list must start with x=0, end with x=1, and
all values of x must be in increasing order. Values between
the given mapping points are determined by simple linear interpolation.
The function returns an array "result" where result[x*(N-1)]
gives the closest value for values of x between 0 and 1.
"""
try:
adata = array(data)
except:
raise TypeError("data must be convertable to an array")
shape = adata.shape
if len(shape) != 2 and shape[1] != 3:
raise ValueError("data must be nx3 format")
x = adata[:,0]
y0 = adata[:,1]
y1 = adata[:,2]
if x[0] != 0. or x[-1] != 1.0:
raise ValueError(
"data mapping points must start with x=0. and end with x=1")
if sometrue(sort(x)-x):
raise ValueError(
"data mapping points must have x in increasing order")
# begin generation of lookup table
x = x * (N-1)
lut = zeros((N,), Float)
xind = arange(float(N))
ind = searchsorted(x, xind)[1:-1]
lut[1:-1] = ( divide(xind[1:-1] - take(x,ind-1),
take(x,ind)-take(x,ind-1) )
*(take(y0,ind)-take(y1,ind-1)) + take(y1,ind-1))
lut[0] = y1[0]
lut[-1] = y0[-1]
# ensure that the lut is confined to values between 0 and 1 by clipping it
clip(lut, 0.0, 1.0)
#lut = where(lut > 1., 1., lut)
#lut = where(lut < 0., 0., lut)
return lut
def makeMappingArray(N, data):
"""Create an N-element 1-d lookup table
data represented by a list of x,y0,y1 mapping correspondences.
Each element in this list represents how a value between 0 and 1
(inclusive) represented by x is mapped to a corresponding value
between 0 and 1 (inclusive). The two values of y are to allow
for discontinuous mapping functions (say as might be found in a
sawtooth) where y0 represents the value of y for values of x
<= to that given, and y1 is the value to be used for x > than
that given). The list must start with x=0, end with x=1, and
all values of x must be in increasing order. Values between
the given mapping points are determined by simple linear interpolation.
The function returns an array "result" where result[x*(N-1)]
gives the closest value for values of x between 0 and 1.
"""
try:
adata = array(data)
except:
raise TypeError("data must be convertable to an array")
shape = adata.shape
if len(shape) != 2 and shape[1] != 3:
raise ValueError("data must be nx3 format")
x = adata[:,0]
y0 = adata[:,1]
y1 = adata[:,2]
if x[0] != 0. or x[-1] != 1.0:
raise ValueError(
"data mapping points must start with x=0. and end with x=1")
if sometrue(sort(x)-x):
raise ValueError(
"data mapping points must have x in increasing order")
# begin generation of lookup table
x = x * (N-1)
lut = zeros((N,), Float)
xind = arange(float(N))
ind = searchsorted(x, xind)[1:-1]
lut[1:-1] = ( divide(xind[1:-1] - take(x,ind-1),
take(x,ind)-take(x,ind-1) )
*(take(y0,ind)-take(y1,ind-1)) + take(y1,ind-1))
lut[0] = y1[0]
lut[-1] = y0[-1]
# ensure that the lut is confined to values between 0 and 1 by clipping it
lut = where(lut > 1., 1., lut)
lut = where(lut < 0., 0., lut)
return lut
