Paper.js operator overloading for vector operations only works when you include the library with type="text/paperscript"
. Otherwise you have to use: add, subtract, multiply, divide, modulo, equals
for +, -, *, /, % and ==
.
like so:
point1.add([ 200, -50 ]);
or for your example:
radius: event.downPoint.subtract(event.point).length,
Here is your example with subtract and here are some more examples and tests.