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<!DOCTYPE html>
<title>Explore the Torus</title>
<style>
body { text-align: center; }
table { margin: auto; }
button { font-size: 250%; }
img { image-rendering: pixelated; }
</style>
<img id="tile" src="tile.png">
<table>
<tr>
<td rowspan="3"><button id="larr" type="button">←</button></td>
<td><button id="uarr" type="button">↑</button></td>
<td rowspan="3"><button id="rarr" type="button">→</button></td>
</tr>
<tr></tr>
<tr>
<td><button id="darr" type="button">↓</button</td>
</tr>
</table>
<script>
let tile = document.getElementById("tile");
let larr = document.getElementById("larr");
let darr = document.getElementById("darr");
let uarr = document.getElementById("uarr");
let rarr = document.getElementById("rarr");
let state = new URLSearchParams(document.location.hash.slice(1));
function setImage() {
let url = new URL(tile.src);
url.search = "?" + state.toString();
tile.src = url.toString();
}
setImage();
function move(dx, dy) {
state.set("x", +state.get("x") + dx);
state.set("y", +state.get("y") + dy);
history.pushState(state.toString(), "", "#" + state.toString());
setImage();
}
window.onpopstate = function(event) {
state = new URLSearchParams(event.state);
setImage();
}
larr.onclick = () => move(-1, 0);
darr.onclick = () => move( 0, 1);
uarr.onclick = () => move( 0, -1);
rarr.onclick = () => move( 1, 0);
document.onkeydown = function(event) {
switch (event.key) {
case "h": case "ArrowLeft": larr.onclick(); break;
case "j": case "ArrowDown": darr.onclick(); break;
case "k": case "ArrowUp": uarr.onclick(); break;
case "l": case "ArrowRight": rarr.onclick(); break;
}
}
</script>
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