icupertino-spring.js

const iSpring = {
    helpers: {
        transition: (firstInput, secondInput, transitionValue) => {
            if (typeof firstInput == "number") {
                return firstInput + (secondInput - firstInput) * transitionValue;
            } else {
                var result = [];
                for (var i = 0; i < firstInput.length; i++) {
                    result[i] = firstInput[i] + (secondInput[i] - firstInput[i]) * transitionValue;
                }
                return result;
            }
        },
    },
    customSpring: function (initial_velocity = 0, initial_position = 1, object_mass = 1, friction_coefficient = 2, spring_constant = 2, duration = 1000) {
        function clc(m, b, k, x0, v0) {
            return function calculate(t) {
                t *= 5000 / duration
                var omega = Math.sqrt(
                    ((4 * m * k - Math.pow(b, 2)) > 0 ? (4 * m * k - Math.pow(b, 2)) : 0) /
                    (2 * m)
                )
                const a = b / 2 * m
                if (omega == 0) {
                    return Math.pow(Math.E, -a * t) * (x0 + ((v0 + a * x0) / (1 / Number.MAX_SAFE_INTEGER)) * Math.sin((1 / Number.MAX_SAFE_INTEGER) * t))
                } else {
                    return Math.pow(Math.E, -a * t) * (x0 * Math.cos(omega * t) + ((v0 + a * x0) / omega) * Math.sin(omega * t))

                }
            }
        }
        if (typeof initial_position == "number") {
            var [m, b, k, x0, v0] = [Number(object_mass), Number(friction_coefficient), Number(spring_constant), Number(initial_position), Number(initial_velocity)]
            return { calculate: clc(m, b, k, x0, v0) }
        } else {
            var calculations = []
            initial_velocity.forEach((value, index) => {
                calculations.push(clc(initial_velocity[index], initial_position[index], object_mass, friction_coefficient, spring_constant, duration))
            });
            return {
                calculate: function (t) {
                    var result = []
                    calculations.forEach(calc => {
                        result.push(calc.calculate(t))
                    });
                    return result;
                }
            }
        }

    },
}
window.iSpring = iSpring