</html>
window.onload = function(){
//some variables
var r, g, b, gray;
var character, line = "";
//sprite stuff
var sprite = document.getElementById("sprite");
var W = sprite.width;
var H = sprite.height;
//temporary canvas for pixel processing
var tcanvas = document.createElement("canvas");
tcanvas.width = W;
tcanvas.height = H; //same as the image
var tc = tcanvas.getContext("2d");
//painting the canvas white before painting the image to deal with pngs
tc.fillStyle = "white";
tc.fillRect(0, 0, W, H);
//drawing the image on the canvas
tc.drawImage(sprite, 0, 0, W, H);
//accessing pixel data
var pixels = tc.getImageData(0, 0, W, H);
var colordata = pixels.data;
//every pixel gives 4 integers -> r, g, b, a
//so length of colordata array is W*H*4
for(var i = 0; i < colordata.length; i = i+4)
{
r = colordata[i];
g = colordata[i+1];
b = colordata[i+2];
//converting the pixel into grayscale
gray = r*0.2126 + g*0.7152 + b*0.0722;
//overwriting the colordata array with grayscale values
colordata[i] = colordata[i+1] = colordata[i+2] = gray;
//text for ascii art.
//blackish = dense characters like "W", "@"
//whitish = light characters like "`", "."
if(gray > 250) character = " "; //almost white
else if(gray > 230) character = "`";
else if(gray > 200) character = ":";
else if(gray > 175) character = "*";
else if(gray > 150) character = "+";
else if(gray > 125) character = "#";
else if(gray > 50) character = "W";
else character = "@"; //almost black
//newlines and injection into dom
if(i != 0 && (i/4)%W == 0) //if the pointer reaches end of pixel-line
{
ascii.appendChild(document.createTextNode(line));
//newline
ascii.appendChild(document.createElement("br"));
//emptying line for the next row of pixels.
line = "";
}
line += character;
}
//repainting the gray image
//tc.putImageData(pixels, 0, 0);
//you can see the grayscale version of the sprite now
//injecting the canvas into the DOM
//sprite.parentNode.insertBefore(tcanvas, sprite);
//you can see the canvas now with the image
//animation time
var frames = 11; //sprite got 10 frames
var container = document.getElementById("container");
//width of container should allow only 1 frame to be seen
var frame_width = parseInt(window.getComputedStyle(container).width)/frames;
//window.getComputedStyle is supported in Chrome, FF, Opera, and IE9+
//The width has "px" at the end so parseInt is used to remove that
container.style.width = frame_width+"px";
//We will change the margin-left of ascii to move it.
ascii.style.marginLeft = "0";
setInterval(loop, 1000/20);
function loop()
{
var current_ml = parseFloat(ascii.style.marginLeft);
//if the ascii reaches the last frame(9th in this case)
//margin needs to be reset to 0
//frame_width * (10-1) * -1(because we are taking the margin negative)
if(current_ml == frame_width*(frames-1)*-1)
ascii.style.marginLeft = "0";
else
ascii.style.marginLeft = (current_ml - frame_width) + "px";
}
}
</script>