Color transfer function values in pvpython

Hi there,

I’m attempting to change the colour of a section within a colour bar without impacting the overall gradient on the points outside the changed section.

The closest I have been to achieving this has been through the GUI:

  • Using the default colour bar, there are 3 data points in the ‘color transfer function values’ table - Image 1.
  • Clicking on the colour bar, I can add more values to the table, each inheriting the RBG value to maintain the natural gradient - Image 2.
  • Then I edit a few of these points and I have a yellow section within the un-affected gradient - Image 3.

Is there a way to obtain the RGB values for certain data points using pvpython?
I’ve not found a way to specify a data point (e.g. 0.3 in the example of my images) and have pvpython return the RBG values that correspond.

Best wishes,

You can get the lookup table object in Python and access its color points with:

lut = GetColorTransferFunction('vOSI')

RGBPoints is a list of doubles in the order (value_0, red_0, green_0, blue_0, value_1, red_1, green_1, blue_1, ...) You can set the RGB points with

lut.RGBPoints = [25.32328370098179, 0.231373, 0.298039, 0.752941, 2474.27393603584, 0.865003, 0.865003, 0.865003, 4923.224588370698, 0.705882, 0.0156863, 0.14902]

for data points 25.32328370098179, 2474.27393603584, and 4923.224588370698, for instance.

Hope that helps!

Hi Corey,

Thank you for the reply!
It half-way helps for sure.

I loaded up the dataset with the default cool-to-warm colour bar and inspected the ‘vOSI’ property.
print(lut.RBGPoints) outputs 3 points with RGB values - start, middle, and end.

Using the GUI on the Color Map Editor, if I then click to make a new point somewhere within that range ParaView creates those RGB values for me.
Is there a function I can call to access those RGB values too?
That way I could write something like this in my script:

# Get the default colour transfer points
lut = GetColorTransferFunction('vOSI')
points = lut.RGBPoints
>>> [[0.0, 0.231373, 0.298039, 0.752941,
	 0.25 0.865003, 0.865003, 0.865003,
	 0.50 0.705882, 0.0156863, 0.14902]

# Add several more points with default colour mapping
new_points = [0.0, 0.15, 0.25, 0.37, 0.50]
new_points_RGB = []
for point in new_points:
	RGB_values = SomeFunctionToGetDefaultRGB(point)

>>> [[0.0, 0.231373, 0.298039, 0.752941,
	0.15, R, G, B,
	 0.25 0.865003, 0.865003, 0.865003,
	0.37, R, G, B,
	 0.50 0.705882, 0.0156863, 0.14902]

# Applly new points
lut.RGBPoints = new_points_RGB

RGB_values = SomeFunctionToGetDefaultRGB(point)
It’s this line I’m most in need of.
Since it seems something like this happens through the GUI I thought the process should be accessible somehow through Python.
It might need some more input data, like this. But do you know if it’s possible?
RGB_values = SomeFunctionToGetDefaultRGB(point, minimum, maximum, color_preset)

Sorry to be a pain!
Best wishes,

You can do this:

rgb = [0, 0, 0]
lut.GetClientSideObject().GetColor(100, rgb)
[0.5647058823529412, 0.6980392156862745, 0.996078431372549]

Brilliant, thank you very much!