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snake edit
<html> <head> <title></title> <style> html, body { height: 100%; margin: 0; }
body { background: black; display: flex; align-items: center; justify-content: center; } canvas { border: 1px solid white; } </style> </head> <body> <canvas width="400" height="400" id="game"></canvas> <script> var canvas = document.getElementById('game'); var context = canvas.getContext('2d');
var grid = 16; var count = 0;
var snake = { x: 160, y: 160,
// snake velocity. moves one grid length every frame in either the x or y direction dx: grid, dy: 0,
// keep track of all grids the snake body occupies cells: [],
// length of the snake. grows when eating an apple maxCells: 4 }; var apple = { x: 320, y: 320 };
// get random whole numbers in a specific range // @see https://stackoverflow.com/a/1527820/2124254 function getRandomInt(min, max) { return Math.floor(Math.random() * (max - min)) + min; }
// game loop function loop() { requestAnimationFrame(loop);
// slow game loop to 15 fps instead of 60 (60/15 = 4) if (++count < 4) { return; }
count = 0; context.clearRect(0,0,canvas.width,canvas.height);
// move snake by it's velocity snake.x += snake.dx; snake.y += snake.dy;
// wrap snake position horizontally on edge of screen if (snake.x < 0) { snake.x = canvas.width - grid; } else if (snake.x >= canvas.width) { snake.x = 0; }
// wrap snake position vertically on edge of screen if (snake.y < 0) { snake.y = canvas.height - grid; } else if (snake.y >= canvas.height) { snake.y = 0; }
// keep track of where snake has been. front of the array is always the head snake.cells.unshift({x: snake.x, y: snake.y});
// remove cells as we move away from them if (snake.cells.length > snake.maxCells) { snake.cells.pop(); }
// draw apple context.fillStyle = 'red'; context.fillRect(apple.x, apple.y, grid-1, grid-1);
// draw snake one cell at a time context.fillStyle = 'green'; snake.cells.forEach(function(cell, index) {
// drawing 1 px smaller than the grid creates a grid effect in the snake body so you can see how long it is context.fillRect(cell.x, cell.y, grid-1, grid-1);
// snake ate apple if (cell.x === apple.x && cell.y === apple.y) { snake.maxCells++;
// canvas is 400x400 which is 25x25 grids apple.x = getRandomInt(0, 25) * grid; apple.y = getRandomInt(0, 25) * grid; }
// check collision with all cells after this one (modified bubble sort) for (var i = index + 1; i < snake.cells.length; i++) {
// snake occupies same space as a body part. reset game if (cell.x === snake.cells[i].x && cell.y === snake.cells[i].y) { snake.x = 160; snake.y = 160; snake.cells = []; snake.maxCells = 4; snake.dx = grid; snake.dy = 0;
apple.x = getRandomInt(0, 25) * grid; apple.y = getRandomInt(0, 25) * grid; } } }); }
// listen to keyboard events to move the snake document.addEventListener('keydown', function(e) { // prevent snake from backtracking on itself by checking that it's // not already moving on the same axis (pressing left while moving // left won't do anything, and pressing right while moving left // shouldn't let you collide with your own body)
// left arrow key if (e.which === 37 && snake.dx === 0) { snake.dx = -grid; snake.dy = 0; } // up arrow key else if (e.which === 38 && snake.dy === 0) { snake.dy = -grid; snake.dx = 0; } // right arrow key else if (e.which === 39 && snake.dx === 0) { snake.dx = grid; snake.dy = 0; } // down arrow key else if (e.which === 40 && snake.dy === 0) { snake.dy = grid; snake.dx = 0; } });
// start the game requestAnimationFrame(loop); </script> </body> </html> <!DOCTYPE html> 185.233.130.25 (talk) 12:45, 27 February 2023 (UTC)