Method splitInflections

src/webgl/text.js:387–432

* @return {Cubic[]} the non-inflecting pieces of this cubic * * returns an array containing 0, 1 or 2 cubics split resulting * from splitting this cubic at its inflection points. * this cubic is (potentially) altered and returned in the list.

()

         * this cubic is (potentially) altered and returned in the list.
         */
        splitInflections() {
          const a = Vector.sub(this.c0, this.p0);
          const b = Vector.sub(Vector.sub(this.c1, this.c0), a);
          const c = Vector.sub(
            Vector.sub(Vector.sub(this.p1, this.c1), a),
            Vector.mult(b, 2)
          );

          const cubics = [];

          // find the derivative coefficients
          let A = b.x * c.y - b.y * c.x;
          if (A !== 0) {
            let B = a.x * c.y - a.y * c.x;
            let C = a.x * b.y - a.y * b.x;
            const disc = B * B - 4 * A * C;
            if (disc >= 0) {
              if (A < 0) {
                A = -A;
                B = -B;
                C = -C;
              }

              const Q = Math.sqrt(disc);
              const t0 = (-B - Q) / (2 * A); // the first inflection point
              let t1 = (-B + Q) / (2 * A); // the second inflection point

              // test if the first inflection point lies on the curve
              if (t0 > 0 && t0 < 1) {
                // split at the first inflection point
                cubics.push(this.split(t0));
                // scale t2 into the second part
                t1 = 1 - (1 - t1) / (1 - t0);
              }

              // test if the second inflection point lies on the curve
              if (t1 > 0 && t1 < 1) {
                // split at the second inflection point
                cubics.push(this.split(t1));
              }
            }
          }

          cubics.push(this);
          return cubics;
        }
      }

      /**