pi-emergence/lib/tentacles/components/tentacle-tip.js

Various emergent phenomena

const NINETY_DEGREES = Math.PI / 2;
const DEGREE_RATIO = 57.2958;

class TentacleSegmentEndpoint { 
    constructor(position = null, options = {}) {
        if (!options) options = {};

        if (!position || !(position instanceof p5.Vector))
            throw new Error("TentacleSegmentEndpoint must be created with a position (p5.Vector) as its first parameter");

        this.position = position;
        this.id = options.id || Math.floor(Math.random() * 9999999999).toString(36) + (new Date()).getTime().toString();
        this.mass = typeof options.mass === "number" ? options.mass : 0.5;
        this.angle = typeof options.angle === "number" ? options.angle : 0;
        this.label = options.label || "";
        this.forces = createVector(0, 0);   // Not used for now
    }

    getDescription(showLabelIfNotEmpty = true, newLine = "\n") {
        if (showLabelIfNotEmpty && !!this.label && this.length > 0) return this.label;
        return `Pos (${this.position.x.toFixed(2)}, ${this.position.y.toFixed(2)})\nAngle: ${(this.angle * DEGREE_RATIO).toFixed(1)}\nMass: ${this.mass.toFixed(2)}`;
    }

 /**
     * Calculates the force vector to apply to this segment (ie, how much space to move/rotate this segment)
     * @param {p5.Vector} forceVector - The force vector to apply to this segment
     * @param {boolean} useBase - Calculate based on the base position and angle (true), or the tip position and angle (false)
     * @returns {p5.Vector} - The force vector to apply to this segment
     */
    addForce(forceVector, angle = null) {
        // Invert the angles
        if (typeof angle !== "number")
            angle = this.angle;
        
        const force = forceVector.copy();

        force.rotate(angle);
        force.mult(this.mass);

        const my = (Math.abs(angle) > HALF_PI) ? -1 : 1;

        const fmag = force.mag();
        force.x *= (forceVector.x - force.y) / -fmag;
        force.y *= my * (forceVector.y - force.x) / fmag;

        this.forces.add(force);

        return force;
    }
    
    updatePositions() { 
        this.position.add(this.forces);
        this.forces.set(0, 0);
        
        return this.position;
    }
}