miércoles, junio 12, 2013

Figuras, poligonos, herencia y polimorfismo en Javascript

Actualmente estoy ayudandole alguien muy especial con el aprendizaje de Javascript y OOP. Para tal objetivo le he asignado varios problemas que debe resolver con Herencia y ese pseudo poliformismo que tiene Javascript, pues nada me he inventado la primera parte de lo que seria la definicion de figuras con Javascript tales como un Cuadrado, Triangulo, Circulo, etc; por ahora el pintado solo muestra en la consola el area y algunos datos mas de la figura, pero la idea seria usar canvas en la segunda parte para imprimir las figuras y en el tercera parte algun mecanismo para obtener la informacion de las figuras del usuarios, pues nada aqui el codigo:


/**
 * User: jsanca
 * Date: 6/12/13
 * Time: 11:10 PM
 */

// Defines a point
function Point (x, y) {

    this.x = x;
    this.y = y;
} // Point


// Basic definition of a Figure, just a point in nowhere.
function Figure (point, name) {

    this.point = point;
    this.name = name;

    this.render = function () {

        console.log("figure: " + this.name + " " +this.point);
    }
} // Figure.

// the points defines some of the sides
function Square (point1, point2, name) {

    Figure.call(this, point1, name);
    this.point2 = point2;

    this.area = function () {

        var side =
            (this.point2.x == this.point.x)?
            this.point2.y - this.point.y:
            this.point2.x - this.point.x;

        return Math.pow(Math.abs(side), 2);
    }

    this.render = function () {

        console.log("square: " + this.name + ", area = " + this.area());
    }
} // Square.

Square.prototype.parent = Figure.prototype;
Square.prototype.constructor = Square;

// the points defines the point angles
function Triangle (point1, point2, point3, name) {

    Figure.call(this, point1, name);
    this.point2 = point2;
    this.point3 = point3;

    this.area = function () {

        var base = 0;
        var verticalHeight = 0;

        if (this.point2.x == this.point.x) {

            base = this.point2.y - this.point.y;
            verticalHeight = this.point.x - this.point3.x;
        } else {

            base = this.point2.x - this.point.x;
            verticalHeight = this.point.y - this.point3.y;
        }


        return 0.5 * Math.abs(base) * Math.abs(verticalHeight);
    }

    this.render = function () {

        console.log("triangle: " + this.name + ", area = " + this.area());
    }
} // Triangle.

Triangle.prototype.parent = Figure.prototype;
Triangle.prototype.constructor = Triangle;

// the points you pass are the diagonal of the rectangle.
function Rectangle (point1, point2, name) {

    Figure.call(this, point1, name);
    this.point2 = point2;

    this.area = function () {

        var width = this.point2.x - this.point.x;
        var height = this.point2.y - this.point.y;

        return Math.abs(width) * Math.abs(height);
    }

    this.render = function () {

        console.log("rectangle: " + this.name + ", area = " + this.area());
    }
} // Rectangle.

Rectangle.prototype.parent = Figure.prototype;
Rectangle.prototype.constructor = Rectangle;

// the points defines the radius
function Circle (point1, point2, name) {

    Figure.call(this, point1, name);
    this.point2 = point2;

    this.radius = function () {

        var radius =
            (this.point2.x == this.point.x)?
                this.point2.y - this.point.y:
                this.point2.x - this.point.x;

        return Math.abs(radius);
    }

    this.circumference = function () {

        var radius = this.radius();

        return 2 * Math.PI * radius;
    }

    this.area = function () {

        var radius = this.radius();

        return Math.PI * Math.pow(radius, 2);
    }

    this.render = function () {

        console.log("circle: " + this.name + ", area = " + this.area() + ", circumference = " + this.circumference() + ", radius = " + this.radius());
    }
} // Circle.

Circle.prototype.parent = Figure.prototype;
Circle.prototype.constructor = Circle;

console.log("Running");
var figuresArray = new Array(
    new Square  (new Point(10,10), new Point(10,30), "Cuadrado 1"),
    new Square  (new Point(10,10), new Point(15,10), "Cuadrado 2"),
    new Triangle(new Point(10,10), new Point(10,20), new Point(0,15), "Mi Triangulito"),
    new Rectangle(new Point(10,10), new Point(20,30), "Mi Rectangulo"),
    new Circle(new Point(10,10), new Point(10,25), "Mi Circulo")
);

figuresArray.forEach(
    function(entry) {

        console.log(entry);
        entry.render();
    }
);




Resultado

Running
Square { point=Point, name="Cuadrado 1", more...}
square: Cuadrado 1, area = 400
Square { point=Point, name="Cuadrado 2", more...}
square: Cuadrado 2, area = 25
Triangle { point=Point, name="Mi Triangulito", more...}
triangle: Mi Triangulito, area = 50
Rectangle { point=Point, name="Mi Rectangulo", more...}
rectangle: Mi Rectangulo, area = 200
Circle { point=Point, name="Mi Circulo", more...}
circle: Mi Circulo, area = 706.8583470577034, circumference = 94.24777960769379, radius = 15

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