blob: a2206ed7f6cda316780fd9638eff859946f98c01 [file] [log] [blame]
<html>
<head>
<title>Canvas 3D</title>
</head>
<body>
<div style="position:relative; padding: 25px">
<canvas id='canvas1' style="position:absolute;"></canvas>
</div>
</body>
<script type="text/javascript">
var canvas = document.getElementById('canvas1');
var ctx = canvas.getContext('webgl');
// Some devices, e.g. krane, have a non-zero rotation in landscape mode. We
// precompensate this via the rotateZ CSS transform. See crbug.com/1046109.
const angle = screen.orientation.angle % 360;
canvas.style.transform = `rotateZ(${angle}deg)`;
// Make the canvas large but still falling inside the viewport; |height|
// also has to account for the Shelf (taskbar) at the bottom.
const integerWidth = Math.min(500, Math.floor(window.innerWidth * 0.9));
const integerHeight = Math.min(300, Math.floor(window.innerHeight * 0.9));
// We need subpixel accuracy for non-integer aspect ratios crbug.com/1042110.
const dpr = window.devicePixelRatio || 1;
canvas.style.border = `${1 / dpr}px solid black`;
if (angle % 180 == 90) {
canvas.width = integerHeight;
canvas.height = integerWidth;
canvas.style.width = `${integerHeight / dpr}px`;
canvas.style.height = `${integerWidth / dpr}px`;
// On krane, the canvas needs to be shifted "rightwards" when the screen is
// rotated 90 or 270 degrees, to bring it in view, see crbug.com/1046445/
const offset = ((integerWidth / dpr) - (integerHeight / dpr)) / 2;
canvas.style.left = `${offset}px`;
//canvas.style.top = `-${offset}px`;
} else {
canvas.width = integerWidth;
canvas.height = integerHeight;
canvas.style.width = `${integerWidth / dpr}px`;
canvas.style.height = `${integerHeight / dpr}px`;
}
var draw_passes_count = 0;
function draw_pass() {
// Consider a seeded random number generator if there are reproducibility
// problems.
ctx.clearColor(0, Math.random(), 0, 1.0);
ctx.clear(ctx.COLOR_BUFFER_BIT);
draw_passes_count++;
}
setInterval(draw_pass, 1000);
function get_draw_passes_count() {
return draw_passes_count;
}
</script>
</html>