spaceinvaders
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<html> | |
<head> | |
<script src="spaceinvaders.js"> </script> | |
</head> | |
<body> | |
<canvas id="spaceinvaders" top="100" left="100" width="600" height="600"> </canvas> | |
<script> | |
window.onload = () => { | |
const game = new SpaceInvadersGame(document.getElementById("spaceinvaders").getContext('2d')); | |
window.onkeydown = game.keypress.bind(game); | |
setInterval(() => {game.tick(); game.draw()}, 100); | |
} | |
</script> | |
</body> | |
</html> |
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class SpaceInvadersGame { | |
constructor(ctx) { | |
this.new_game(); | |
this.ctx = ctx | |
} | |
new_game() | |
{ | |
this.width = 600; | |
this.height = 600; | |
this.enemies = []; | |
for(let i = 75; i < 550 ; i += 50) | |
{ | |
for( let j = 75; j < 250; j+= 50) | |
{ | |
this.enemies.push({x: i, y:j}); | |
} | |
} | |
this.spaceship = {x:300, y: 600}; | |
this.spanceship_direction = 0; | |
this.enemies_x_position = 5; | |
this.enemies_move_orientation = 1; | |
this.game_started = false; | |
} | |
check_game_end() | |
{ | |
for (let enemy of this.enemies) | |
{ | |
if (enemy.y > this.spaceship.y - 27 ) | |
{ | |
return true; | |
} | |
} | |
return false; | |
} | |
tick() { | |
if (this.game_started) { | |
if(this.check_game_end()) | |
{ | |
alert("You lose"); | |
this.new_game(); | |
} | |
// Move the spaceship | |
this.spaceship.x += this.spanceship_direction * 5; | |
this.spanceship_direction = 0; | |
// move the enemies | |
this.enemies_x_position += this.enemies_move_orientation; | |
let offset_x = this.enemies_move_orientation * 10; | |
let offset_y = 0; | |
if (this.enemies_x_position === 0) { | |
this.enemies_move_orientation = 1; | |
offset_y = 20; | |
} | |
else if (this.enemies_x_position === 10) { | |
this.enemies_move_orientation = -1; | |
offset_y = 20; | |
} | |
for (let enemy of this.enemies) { | |
enemy.x += offset_x; | |
enemy.y += offset_y; | |
} | |
} | |
} | |
draw() | |
{ | |
this.ctx.clearRect(0, 0, this.width, this.height); | |
this.ctx.fillStyle = "black"; | |
this.ctx.strokeStyle = "black 2px solid"; | |
this.ctx.fillRect(0, 0, this.width, this.height); | |
this.ctx.fillStyle = "red"; | |
this.ctx.strokeStyle = "red 2px solid"; | |
for (let enemy of this.enemies) | |
{ | |
this.ctx.fillRect(enemy.x-12, enemy.y-12, 25, 15); | |
} | |
this.ctx.fillStyle = "blue"; | |
this.ctx.strokeStyle = "blue 2px solid"; | |
this.ctx.fillRect(this.spaceship.x - 25, this.spaceship.y -15, 50, 15) | |
} | |
keypress(event) | |
{ | |
this.spanceship_direction = { | |
37: -1, // Left | |
39: 1, // Right | |
}[event.keyCode] || 0; | |
this.game_started = { | |
13: true, | |
27: true | |
}[event.keyCode] ? !this.game_started: this.game_started; | |
} | |
} |
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