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tetris-main.js
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tetris-main.js
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//Define inital variables
var canvas;
var ctx;
var dx = 5; //x-axis movement
var dy = 5; //y-axis movement
var x = 150; //x-axis position
var y = -50; //y-axis position
//DEFINE AN EVENT LISTENER
//Step 1: start the following line on page load...
window.onload = function()
{
window.addEventListener('keydown',pressArrowKeys,true);
canvas = document.getElementById("canvas");
ctx = canvas.getContext("2d");
return setInterval(draw,5);
}
//FUNCTION CALLED WHEN USER PRESSES ONE OF THE ARROWS
//We are trying to find out what key the user pressed
function pressArrowKeys(event)
{
switch (event.keyCode)
{
//Disable usage of 'up' and 'down' arrow
/* case 38:
y -= dy;
break;
case 40:
y += dy;
break; */
case 37: //LEFT
x -= dx;//Substraction assignment on x-axis
break;
case 39: //RIGHT
x += dx;//Addition assignment on x-axis
break;
}
}
//INITIATE DRAW FUNCTION
function draw()
{
ctx.clearRect(0, 0, 500, 500);//RE-DRAW CANVAS ON EACH ACTION
//RE-DRAW OBJECT
ctx.beginPath();
ctx.arc(x,y,10,0,2*Math.PI);
ctx.fill();
y +=.002;
var loopTimer = setTimeout('draw('+x+','+y+')',0,2000);
}