I love the Tiny Platformer tutorial that’s on Code inComplete (http://codeincomplete.com/posts/2013/5/27/tiny_platformer/), however the way it’s structured makes it hard to actually use in a 2 hour tutorial session. So I’ve instead broken it down into 4 parts.
Lesson 1: Rendering a map
In order to render a map, we have some variables that define our world:
var MAP = { tw: 64, th: 48 }, // the size of the map (in tiles)
TILE = 32, // the size of each tile (in game pixels)
METER = TILE; // abitrary choice for 1m
var canvas = document.getElementById('canvas'),
ctx = canvas.getContext('2d'),
width = canvas.width = MAP.tw * TILE,
height = canvas.height = MAP.th * TILE,
player = { x: 320, y: 320, dx: 0, dy: 0 };
var t2p = function(t) { return t*TILE; },
p2t = function(p) { return Math.floor(p/TILE); };
The t2p and p2t functions convert from the tile number to the pixel number, and vice versa.
Also, some level data:
var COLOR = { BLACK: '#000000', YELLOW: '#ECD078', BRICK: '#D95B43', PINK: '#C02942', PURPLE: '#542437', GREY: '#333', SLATE: '#53777A' },
COLORS = [ COLOR.BLACK, COLOR.YELLOW, COLOR.BRICK, COLOR.PINK, COLOR.PURPLE, COLOR.GREY ];
var cells = [5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 5, 0, 0, 0, 0, 0, 0, 0, 0, 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cell = function(x,y) { return tcell(p2t(x),p2t(y)); },
tcell = function(tx,ty) { return cells[tx + (ty*MAP.tw)]; };
This giant array tells you how to fill in each tile.
Next, we’ll actually render the player and the map:
function frame() {
render(ctx);
requestAnimationFrame(frame, ctx);
}
function render(ctx) {
// render map
var x, y;
for(y = 0 ; y < MAP.th ; y++) {
for(x = 0 ; x < MAP.tw ; x++) {
ctx.fillStyle = COLORS[tcell(x,y)];
ctx.fillRect(x * TILE, y * TILE, TILE, TILE);
}
}
// render player
ctx.fillStyle = COLOR.YELLOW;
ctx.fillRect(player.x, player.y, TILE, TILE);
}
frame();
This basically reads the array, which represents the map, and fills in each tile according to the color the map represents.
Running this code should give you a map; next week, moving the player.