![]() When you finish share a link to your CodePen / GitHub repository in the comments. This challenge is just to practice drawing shapes on the canvas, not to create some complex game character. If your drawing needs a lot of curves, look into the bezier curve functions: quadraticCurveTo and bezierCurveTo.If you did the grid challenge from earlier, now is a good time to use it.Use canvas.height / 2 and canvas.width / 2 to get the center X, Y of the canvas.Search for examples on CodePen to get ideas (prepare to be overwhelmed by the crazy art some people make).Landscape - draw a house, some grass, a sun or perhaps a starry night sky.Charts (bar chart, pie chart, etc) - a little more advanced and I’ll be doing another tutorial on charts but if you want to try it on your own go for it.Find some reference images or make something up. Now it’s time to put everything you’ve learned to use, here’s your challenge:ĭraw a picture using a combination of the shapes we learned. 4th square, uses the same style defined previously ctx.beginPath() ctx.rect(275, 35, 50, 50) ctx.fill() ctx.stroke() For example, if we add a fourth square using the code below it would have the same style as the third square. Setting the fill or stroke style will cause any shapes created after, to have the same style. You can just as easily set ctx.fillStyle and use ctx.fillRect() Note: We did not need to use the ctx.rect() function just to change the colors, we used it because we wanted both a stroke and a fill. Draw the path to the screen - using fill or stroke.Use the path functions to create a shape - i.e.Begin the path - start creating the virtual path (not drawn to screen yet).Set the styles - optional and can be set any time before rendering.‘blue’, ‘rgba(200, 200, 150, 0.5)’, etcĬtx.fillStyle = ‘any valid css color’ - same as above but for the fillĬtx.lineWidth = number - sets the stroke widthĭrawing any shape always follows these steps: It creates a path for the square in memory, we then configure the stroke, fill, and stroke width before calling ctx.fill and/or ctx.stroke to draw it on screenĬtx.strokeStyle = ‘any valid css color’ - sets the outline/stroke color to any string that works in CSS. You can play with the example below on this page.Ĭtx.rect(x, y, width, height) - this is like the other two rectangle methods, but it does not immediately draw it. (X: 0, Y: 0) Moving down or to the right increases X and Y positions. The Canvas Coordinate Systemīy default, the coordinate system starts at the top left. We’ll talk more about security in a future article, for now, let’s get to drawing stuff. The semicolon is there in case some other code is loaded before ours and it doesn’t have a semicolon at the end. This has several benefits such as preventing players (if this were a game) from accessing your variables directly and prevents your code from colliding with someone else's code (such as a library or another script on the website). We use it to prevent our code from leaking out in the global scope. This is an immediately invoked function expression (IIFE). If you were working with 3D, you would use WebGL instead.īut wait what’s with the function thingy wrapping all of this? The 2D context contains the set of tools we want. Once it finds the element, we can then manipulate it with JavaScript.Ĭanvas.getContext() - context is our toolbox of paintbrushes and shapes. ![]() ![]() Grab the canvas element and create a 2D contextĭocument.getElementById('gameCanvas') - searches for an HTML element that has the id of gameCanvas. Steps 3 and 4 Get the canvas element by id, then use it to get the “2d” context. I also changed the canvas background to be white and added some margin to the bottom. For this project, I will change the canvas width/height to be 800x1200 to give us plenty of space. Steps 1 and 2 for this project Our boilerplate / CodePen template already covered setting up the basic styles and adding a canvas element. We’ll do steps one and two in HTML/CSS, but you could do it in JavaScript if you prefer. Use the canvas element to get the context (your toolbox more on it later).In JavaScript, get your canvas element by using the id.Add base styles - center the canvas, add a background color, etc (CSS).Create the canvas element - give it an id, and a width/height (HTML).When working with a canvas there are five steps to get started. Used often today for creating games and visualizations (data or artistic).Graphics can be 2D or 3D and it’s able to use hardware acceleration.Introduced with HTML version 5 to draw graphics using JavaScript.Some quick bullet points to introduce you to the canvas. In fact, since we’ll be covering many examples, I encourage you to play with it and make a mess. Note: As the focus of this tutorial is not building a project, you don’t need to copy every line exactly.
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