mvtf

from yt.mods import *

pf = load('plt_derr_perr_grav_00100')

# We'll use 2 fields for our MVTF
field1 = 'density'
field2 = 'Temp'

dd = pf.h.all_data()
mi, ma = dd.quantities['Extrema'](field1)[0]
tmi, tma = dd.quantities['Extrema'](field2)[0]
mi, ma = np.log10(mi), np.log10(ma)
tmi, tma = np.log10(tmi), np.log10(tma)

den_x_bounds = (mi-1, ma+1)
temp_x_bounds = (tmi-1, tma+1)
nbins = 1.0e6

# We'll use logs here
pf.field_info[field1].take_log=True
pf.field_info[field2].take_log=True


# Initialize the MVTF
mv = MultiVariateTransferFunction()

# Create our transfer functions--note that we'll be using a
# combination of both blue and green for temperature, and red
# for density
red = TransferFunction(den_x_bounds, nbins)
blue_green = TransferFunction(temp_x_bounds, nbins)
alpha = TransferFunction(den_x_bounds, nbins)

# Add our transfer function to the MVTF. By saying red's
# field_id is 0, we are also saying that 0 will be the index
# for density in the camera object's field list
mv.add_field_table(red, 0)
mv.add_field_table(blue_green, 1)
mv.add_field_table(alpha, 0)

# Link channels. This is where we specify that we want 'red'
# to go to the red channel, etc.
mv.link_channels(0,0)
mv.link_channels(1,[1,2])
mv.link_channels(2,3)

# Add gaussians to our transfer functions--this can be done
# any time after they are created
locs = [np.log10(1.2e7), np.log10(5.0e6)]
wi = [1.0e-6, 1.0e-4]
h = 20.0

red.add_gaussian(locs[0], wi[1], h)
red.add_gaussian(locs[1], wi[1], h)
blue_green.add_gaussian(locs[0], wi[0], h)

mv.grey_opacity=False

# Initialize the camera with the correct field list, take a
# snapshot, and save the image
c = [5.0e9, 5.0e9, 5.0e9]
L = [0.15, 1.0, 0.40]
W = (pf.domain_right_edge - pf.domain_left_edge)*0.7
Nvec = 1024

cam = pf.h.camera(c, L, W, (Nvec,Nvec), transfer_function = mv,
                  fields=['density', 'Temp'], pf=pf, no_ghost=True)
im = cam.snapshot(num_threads=4)
im.write_png('den_temp_mvtf.png')