Blending Colors within a shape

I am trying to model a blood vessel going through the lung and Oxygen being added to the blood. So the beginning of the vessel should be purple and the end of the vessel should be red. Is there a way to split the vessel in half. Color the first half purple and the second half red and then have the colors blend and change along the length of the vessel, representing the deoxygenated blood (purple) slowly gaining oxygen and turning red by the end. Sorry if this is wordy.

Make a graduated image [PNG] in a program like Gimp or PhotoShop.
Grading its hues from purple to red.
Save it.
Draw a [temporary] rectangle the length of the ‘tube’ - make it along side but not touching it.
Import the PNG as a Texture.
Scale the size of it to fit onto the rectangle’s length.
Now select that textured face - Context-menu > Texuture > Projected.
If the ‘tube’ is in a group edit it so you are working on its surface.
Switch View > Hidden Geometry OFF if you need to so you will paint the whole tube’s surface and not individual facets.
Now open the Material Browser.
Use the eyedropper to select the newly projected-material aka texture] from the rectangle’s face.
Immediately use the paintbucket cursor to paint that projected-material onto the ‘tube’.
It should now be all graduated purple-to-red…
Delete the unwanted temporary rectangle to tidy up…


Here’s another example showing a thermal gradient along a pipe spool:


Incidentally, I don’t think this is the proper category for questions. It is intended for users who wish to post a tutorial for others to study demonstrating and explaining some common modeling procedure. You can ask questions of this nature in the “SketchUp” category. -G


I’ve moved it to the SketchUp Category.
Geo … Help Forum Janitor

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