Empresas
Empleos
  • Sobre nosotros
  • Soluciones
    • Publicación de vacantes
      Publica tu vacante y recibe candidatos calificados en 48h.
    • Evaluación de candidatos
      500+ pruebas técnicas y psicológicas, más anti-fraude.
    • Headhunting
      Búsqueda ejecutiva a la medida de principio a fin.
    • Nómina + EOR
      Dispersión de nómina y EOR en más de 15 países de LATAM.
  • Precios
  • Empleos

0

169
Vistas
trying to draw a rectangle and it is not showing up but there's no error

I've created an animation loop that works fine, but when I created a function to draw a rectangle, nothing shows up. I don't get an error but the rectangle doesn't appear. I did console.log("hello") at the end of the rect function to make sure it works, and "hello" does appear in console, so at this point, I don't know what's wrong. Any help would be greatly appreciated.

Here's my complete code:

///// VARIABLES 

var canvas;
var ctx;
var w = 1000;
var h = 600; 

///// EXECUTABLE CODE 

setUpCanvas();


var o1 = {
    "x": w/3,
    "y": h/3,
    "w": 20,
    "h": 20,
    "c": 180,
    "a": 0.5,
    "angle": 0,
    "changle": 30,
    "distance": 50,

}

var o2 = {
    "x": w/3,
    "y": h/3,
    "c": 280,
    "a": 0.5,
    "w": 0,
    "h": 30, 
}


var oneDegree = 2*Math.PI/360;



setUpCanvas();



animationLoop();

rect(o2);

function animationLoop(){
    clear();
    shape(o1);
    angle(o1,2);
    forward(o1,10);

    requestAnimationFrame(animationLoop);
}

function clear(){
    ctx.clearRect(0,0,w,h);
}


function shape(o){
    var x = o.x;
    var y = o.y;
    var a = o.angle;
    ctx.beginPath();
    ctx.moveTo(o.x,o.y);
    for ( var i=0; i<300; i++){
        angle(o, 10);
        forward(o,2+i*10);
        ctx.lineTo(o.x, o.y);
        ctx.stroke();
    }
    o.x = x;
    o.y = y;
    o.angle = a;
}


function angle(o,a){ 
    // console.log(a);
    if( a == undefined){
        o.angle += o.changle;
    }else{
    o.angle += a;
    }
}


function forward(o,d){
    var cX;
    var cY;

    if(d != undefined){
        o.distance= d;    
    };
        cX = o.distance*Math.cos(o.angle*oneDegree*5);
        cY = o.distance*Math.sin(o.angle*oneDegree*5);
        o.x += cX;
        o.y += cY;
    
}


function rect(o){
    ctx.beginPath();
    ctx.moveTo(o.x , o.y);
    ctx.lineTo(o.x+o.w, o.y);
    ctx.lineTo(o.x+o.w, o.y+o.h);
    ctx.lineTo(o.x, o.y+o.h);
    ctx.lineTo(o.x, o.y);
    ctx.fillStyle = "hsla("+o.c+", 100%, 50%, "+o.a+")";
    ctx.fill();
   
}

//GENERAL STUFF
function randn(r){
    var result = Math.random()*r - r/2;
    return result;
}

function randi(r){
    var result = Math.floor(Math.random()*r);
    return result 
}

function rand(r){
    var result = Math.random()*r;
    return result
}

function setUpCanvas(){
    canvas = document.querySelector("#myCanvas");
    ctx = canvas.getContext("2d");
    canvas.width = w;
    canvas.height = h;
    canvas.style.border="2px solid black";
}

console.log("Assignment 2");
about 4 years ago · Juan Pablo Isaza
1 Respuestas
Responde la pregunta

0

I can see the rectangle, I changed the color of the rectangle to red to make it more visible to myself. Your code is correct. Did I miss anything? here is the snippet, it just your code

///// VARIABLES 

var canvas;
var ctx;
var w = 1000;
var h = 600; 

///// EXECUTABLE CODE 

setUpCanvas();

var o1 = {
    "x": w/3,
    "y": h/3,
    "w": 20,
    "h": 20,
    "c": 180,
    "a": 0.5,
    "angle": 0,
    "changle": 30,
    "distance": 50,

}

var o2 = {
    "x": w/3,
    "y": h/3,
    "c": 280,
    "a": 0.5,
    "w": 0,
    "h": 30, 
}


var oneDegree = 2*Math.PI/360;



setUpCanvas();

animationLoop();

rect(o2);
myRect(o2);

function animationLoop(){
    clear();
    shape(o1);
    angle(o1,2);
    forward(o1,10);

    requestAnimationFrame(animationLoop);
}

function clear(){
    ctx.clearRect(0,0,w,h);
}


function shape(o){
    var x = o.x;
    var y = o.y;
    var a = o.angle;
    ctx.beginPath();
    ctx.moveTo(o.x,o.y);
    for ( var i=0; i<300; i++){
        angle(o, 10);
        forward(o,2+i*10);
        ctx.lineTo(o.x, o.y);
        ctx.stroke();
    }
    o.x = x;
    o.y = y;
    o.angle = a;
}


function angle(o,a){ 
    // console.log(a);
    if( a == undefined){
        o.angle += o.changle;
    }else{
    o.angle += a;
    }
}


function forward(o,d){
    var cX;
    var cY;

    if(d != undefined){
        o.distance= d;    
    };
        cX = o.distance*Math.cos(o.angle*oneDegree*5);
        cY = o.distance*Math.sin(o.angle*oneDegree*5);
        o.x += cX;
        o.y += cY;
    
}

function myRect(o){
 
    //ctx.fillStyle = "hsla("+o.c+", 100%, 50%, "+o.a+")";
    
    ctx.beginPath();
    ctx.lineWidth = "2";
    ctx.strokeStyle = "green";
    ctx.rect(o.x, o.y, o.x+o.w, o.y+o.h);
    ctx.stroke();
   
}

function rect(o){
    ctx.beginPath();
    ctx.moveTo(o.x , o.y);
    ctx.lineTo(o.x+o.w, o.y);
    ctx.lineTo(o.x+o.w, o.y+o.h);
    ctx.lineTo(o.x, o.y+o.h);
    ctx.lineTo(o.x, o.y);
    ctx.fillStyle = "hsla("+o.c+", 100%, 50%, "+o.a+")";
    ctx.fill();
   
}

//GENERAL STUFF
function randn(r){
    var result = Math.random()*r - r/2;
    return result;
}

function randi(r){
    var result = Math.floor(Math.random()*r);
    return result 
}

function rand(r){
    var result = Math.random()*r;
    return result
}

function setUpCanvas(){
    canvas = document.querySelector("#myCanvas");
    ctx = canvas.getContext("2d");
    canvas.width = w;
    canvas.height = h;
    canvas.style.border="2px solid red";
}

console.log("Assignment 2");
<canvas id="myCanvas" width="150" height="150"></canvas>

about 4 years ago · Juan Pablo Isaza Denunciar
Responde la pregunta
Encuentra empleos remotos

¡Descubre la nueva forma de encontrar empleo!

Top de empleos
Top categorías de empleo
Empresas
Publicar vacante Precios Comercial
Legal
Términos y condiciones Política de privacidad
© 2026 PeakU Inc. All Rights Reserved.
Andres GPT
Recomiéndame algunas ofertas
Necesito ayuda