xseignard/leapLamp

const five = require('johnny-five');

/**
 * Joint of the arm
 */
class Joint {

    constructor(opts) {
        // lowest hand postion tracked
        this.minPos = opts.minPos;
        // highest position tracked
        this.maxPos = opts.maxPos;
        // servo instance that handle this joint
        this.servo = new five.Servo({
            pin: opts.pin,
            range: opts.range,
        });
    }

    /**
     * Move the joint of the calculated angle
     * @param {Number} pos - tracked hand/finger position
     * @param {function()} constraint - if present, a constraint to apply to the current position
     */
    move(pos, constraint) {
        let constrainedPos;
        if (constraint) constrainedPos = constraint(pos);
        else constrainedPos = pos;
        const angle = this.scale(constrainedPos);
        this.servo.to(angle);
    }

    /**
     * Map a given position to the corresponding angle
     * @param {Number} pos - positon to map from its range to the range of angle
     * @return {Number} the corresponding angle
     */
    scale(pos) {
        // if current hand/finger position is outside the tracked range
        // get the nearest tracked limit
        let constrainedPos;
        if (pos < this.minPos) constrainedPos = this.minPos;
        else if (pos > this.maxPos) constrainedPos = this.maxPos;
        else constrainedPos = pos;
        return Math.floor(
            five.Fn.map(
                constrainedPos,
                this.minPos,
                this.maxPos,
                this.servo.range[0],
                this.servo.range[1]
            )
        );
    }
}

module.exports = Joint;