Created
January 13, 2024 06:41
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Space Invader Demo
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| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="UTF-8"> | |
| <meta name="viewport" content="width=device-width, initial-scale=1.0"> | |
| <title>Space invaders</title> | |
| </head> | |
| <body> | |
| <canvas id="canvas" style="height: 100vh; image-rendering: pixelated; image-rendering: crisp-edges;" width="100" | |
| height="100"></canvas> | |
| </body> | |
| <script src="./main.js"></script> | |
| </html> |
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| const canvas = document.getElementById('canvas') | |
| const ctx = canvas.getContext("2d") | |
| const canvasWidth = 100 | |
| const canvasHeight = 100 | |
| let x = 0 | |
| let y = 0 | |
| let velocityX = 2 | |
| let velocityY = 1 | |
| let size = 10 | |
| let invaderX = 50 | |
| let invaderY = 20 | |
| const invaderWidth = 10 | |
| const invaderHeight = 5 | |
| let invaderDead = false | |
| function eventToGameSpace(e) { | |
| return [ | |
| (e.clientX - e.target.offsetLeft) / e.target.clientWidth * canvasWidth, | |
| (e.clientY - e.target.offsetTop) / e.target.clientHeight * canvasHeight | |
| ] | |
| } | |
| canvas.addEventListener('click', (e) => { | |
| const [x, y] = eventToGameSpace(e) | |
| if( | |
| isCollided(invaderX, invaderY, invaderWidth, invaderHeight, x, y, 1, 1) | |
| ) invaderDead = true; | |
| }) | |
| function isCollided(x1, y1, w1, h1, x2, y2, w2, h2) { | |
| return x1 < x2 + w2 && | |
| x1 + w1 > x2 && | |
| y1 < y2 + h2 && | |
| y1 + h1 > y2 | |
| } | |
| function invader(x, y, dead) { | |
| ctx.fillStyle = dead ? 'red' : 'white' | |
| ctx.fillRect(x, y, invaderWidth, invaderHeight) | |
| ctx.fillStyle ='red' | |
| ctx.fillRect(x + 3, y + 2, 1, 1) | |
| ctx.fillRect(x + 6, y + 2, 1, 1) | |
| } | |
| function draw() { | |
| ctx.fillStyle ='black' | |
| ctx.fillRect(0, 0, canvasWidth, canvasHeight) | |
| x += velocityX | |
| y += velocityY | |
| if (x > canvasWidth || x < 0) velocityX *= -1 | |
| if (y > canvasHeight || y < 0) velocityY *= -1 | |
| ctx.fillStyle ='white' | |
| ctx.fillRect(x, y, size, size) | |
| const isDead = isCollided(x, y, size, size, invaderX, invaderY, invaderWidth, invaderHeight) | |
| invader(invaderX, invaderY, isDead || invaderDead) | |
| window.requestAnimationFrame(draw); | |
| } | |
| draw() |
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