import type { ReadonlyVec , Vec } from "@thi.ng/vectors" ; import { addW2 } from "@thi.ng/vectors/addw" ; import { normalize } from "@thi.ng/vectors/normalize" ; import { sub } from "@thi.ng/vectors/sub" ; export const quadraticTangentAt = ( out , a , b , c , t , len = 1 ) => normalize ( out , addW2 ( out , sub ( out , b , a ) , sub ( [ ] , c , b ) , 2 * ( 1 - t ) , 2 * t ) , len ) ;