message: calculate interior tangent for both right and left side
diff: @@ -400,29 +400,24 @@ namespace MakerJs.path {
  //get X of c2 origin
  var x = c2.origin[0];
  - //see if c2 is outside of c1
  - if (round(x - c2.radius) > c1.radius) {
  - return null;
  - }
  + //see if circles are tangent interior on left side
  + if (round(c2.radius - x - c1.radius) == 0) {
  - //see if c2 is within c1
  - if (round(x + c2.radius) < c1.radius) {
  + if (options.excludeTangents) {
  return null;
  }
  - //see if c1 is within c2
  - if (round(x - c2.radius) < -c1.radius) {
  - return null;
  + return [[unRotate(180)], [unRotate(180)]];
  }
  - //see if circles are tangent interior
  - if (round(c2.radius - x - c1.radius) == 0) {
  + //see if circles are tangent interior on right side
  + if (round(c2.radius + x - c1.radius) == 0) {
  if (options.excludeTangents) {
  return null;
  }
  - return [[unRotate(180)], [unRotate(180)]];
  + return [[unRotate(0)], [unRotate(0)]];
  }
  //see if circles are tangent exterior
  @@ -435,6 +430,21 @@ namespace MakerJs.path {
  return [[unRotate(0)], [unRotate(180)]];
  }
  + //see if c2 is outside of c1
  + if (round(x - c2.radius) > c1.radius) {
  + return null;
  + }
  +
  + //see if c2 is within c1
  + if (round(x + c2.radius) < c1.radius) {
  + return null;
  + }
  +
  + //see if c1 is within c2
  + if (round(x - c2.radius) < -c1.radius) {
  + return null;
  + }
  +
  function bothAngles(oneAngle: number): number[] {
  return [unRotate(oneAngle), unRotate(angle.mirror(oneAngle, false, true))];
  }
  