startUp01
<canvas width="450" height="350" id="startUp01" style="background-color:rgba(255, 255, 255, 1.0);"></canvas>
<script>
var canvas = document.getElementById('startUp01');
var context = canvas.getContext('2d');
var x = canvas.width / 2;
var y = canvas.height / 2;
var size = 5;
var vect_x = 1;
var vect_y = 1;
function draw(){
context.globalCompositeOperation = "source-over";
context.fillStyle = "black";
context.globalAlpha = 1.0;
context.fillRect(0, 0, canvas.width, canvas.height);
context.beginPath();
context.globalCompositeOperation = "lighter";
context.fillStyle = "white";
context.globalAlpha = 0.5;
context.arc(x, y, size, 0, Math.PI*2, false);
context.fill();
x += vect_x;
y += vect_y;
if(x < 0 || x > canvas.width){
vect_x *= -1;
}
if(y < 0 || y > canvas.height){
vect_y *= -1;
}
}
setInterval(draw,32);
</script>
Ende;