Add color gradient to AxesHelper

Questions
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1

All 3 of the AxesHelper’s axes use a color gradient by default. I want to change the colors to e.g. magenta, yellow and cyan but also add a color gradient (with lighter/partially transparent tips).

setColors only takes number | Color | string as a parameter. How do I pass a color gradient? Is that possible with THREE.Color?

I tried to create a simple gradient between red and blue with lerp but the axis turned purple, so that’s probably not the correct thing to use for a static gradient (I don’t want an animation):

let axesHelper = new THREE.AxesHelper(10);
let xcol = new THREE.Color("red");
xcol = xcol.lerp(new THREE.Color("blue"),0.5);
axesHelper = axesHelper.setColors(xcol,axisYColor,axisZColor);
scene.add(axesHelper);