Three.js WebGL Draw a circle custom fill and border color from shader

Three.js WebGL Draw a circle custom fill and border color from shader

I'm using Three.js with the WebGLRenderer. I'm trying to figure out or see
an example for how to draw circles using CircleGeometry and be able to
control their fill and border color from a vertex or fragment shader. Is
this even possible without using an image for the texture? Sorry if this
is really simple, I'm still trying to wrap my head around Three.js and
WebGL so any help is appreciated.