def make_volume_prop(mins=255, maxs=355):
"""Make a volume property for the testing."""
table = tvtk.VolumeProperty()
ctf = ColorTransferFunction()
ds = (maxs - mins) / 4.0
try:
ctf.range = (mins, maxs)
except Exception:
# VTK versions < 5.2 don't seem to need this.
pass
ctf.add_rgb_point(mins, 0.00, 0.0, 1.00)
ctf.add_rgb_point(mins + ds, 0.25, 0.5, 0.75)
ctf.add_rgb_point(mins + 2 * ds, 0.50, 1.0, 0.50)
ctf.add_rgb_point(mins + 3 * ds, 0.75, 0.5, 0.25)
ctf.add_rgb_point(maxs, 1.00, 0.0, 0.00)
otf = PiecewiseFunction()
otf.add_point(mins, 0.0)
otf.add_point(maxs, 0.2)
table.set_color(ctf)
table.set_scalar_opacity(otf)
return table, ctf, otf
def make_CTF(x1, x2, hue_range=(2.0/3.0, 0.0),
sat_range=(1.0, 1.0), val_range=(1.0, 1.0),
n=10, mode='sqrt'):
"""Creates a CTF as per given arguments. Lets one set a hue,
saturation and value range. The mode can be one of 'sqrt', or
'linear'. The idea of this function is to create a CTF that is
similar to the LUT being used. 's_curve' is not implemented.
Patches welcome.
"""
maxs = max(x1, x2)
mins = min(x1, x2)
ds = maxs - mins
dhue = hue_range[1] - hue_range[0]
dsat = sat_range[1] - sat_range[0]
dval = val_range[1] - val_range[0]
ctf = ColorTransferFunction()
try:
ctf.range = (mins, maxs)
except Exception:
# VTK versions < 5.2 don't seem to need this.
pass
if mode == 'sqrt':
for i in range(n+1):
# Generate x in [0, 1]
x = 0.5*(1.0 + cos((n-i)*pi/n)) # Chebyshev nodes.
h = hue_range[0] + dhue*x
s = sat_range[0] + dsat*x
v = val_range[0] + dval*x
r, g, b, a = [sqrt(c) for c in hsva_to_rgba(h, s, v, 1.0)]
ctf.add_rgb_point(mins+x*ds, r, g, b)
elif mode == 'linear':
for i in range(n+1):
# Generate x in [0, 1]
x = float(i)/n # Uniform nodes.
h = hue_range[0] + dhue*x
s = sat_range[0] + dsat*x
v = val_range[0] + dval*x
r, g, b, a = hsva_to_rgba(h, s, v, 1.0)
ctf.add_rgb_point(mins+x*ds, r, g, b)
return ctf
