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J'ai un problème à faire tourner une balle qui rebondit autour de l'écran quand je mets la méthode de rotation dedans qui disparaît de la toile dans un très grand arc tournant. Ca fonctionne quand la balle est statique mais quand je mets la vitesse x, y le problème commence. Ant aide quelqu'un peut me donner serait grandement apprécié. S'il vous plaît voir ci-dessous le code que j'ai jusqu'à présent.html5 canvas faire pivoter une balle qui rebondit
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Canvas</title>
<style type="text/css">
canvas {
border: 1px solid black;
}
body {
background-color: white;
}
</style>
</head>
<body>
<canvas id="canvas-for-ball"></canvas>
<script type="text/javascript">
// Gets a handle to the element with id canvasOne.
var canvas = document.getElementById("canvas-for-ball");
// Get a 2D context for the canvas.
var ctx = canvas.getContext("2d");
canvas.width = 500;
canvas.height = 500;
// The vertical location of the ball.
//var y = 10;
var yvel = 3;
var xvel = 3 ;
//ball object
var ball = {
x: 90,
y: 150,
r: 50
};
// A function to repeat every time the animation loops.
function repeatme() {
//clear canvas for each frame of the animation.
ctx.clearRect(0,0,500,500);
// Draw the ball (stroked, not filled).
//for loop to draw each line of th pie.
// i is set to 7. set i to whatever amount of sections you need.
for (var i = 0; i < 7; i++) {
//starting point
ctx.beginPath();
//move to positions the pen to the center of the ball
ctx.moveTo(ball.x, ball.y);
//circle craeted with x,y and r set. The final two arguments (Starting and ending point)
//change over each itteration of the loop giving a new point on the circle to draw to.
ctx.arc(ball.x, ball.y, ball.r, i*(2 * Math.PI/7), (i+1)*(2 * Math.PI/7));
//set line width
//set colour of the lines
ctx.strokeStyle = '#444';
//render the lines
ctx.stroke();
}
ctx.beginPath();
//the inner circle of the pizza
ctx.moveTo(ball.x, ball.y);
//ball.r is used - 10 pixles to put the smaller circle in the pizza.
ctx.arc(ball.x,ball.y,ball.r-10,0,2*Math.PI);
ctx.lineWidth = 2;
ctx.strokeStyle = '#444';
ctx.stroke();
ctx.translate(ball.x, ball.y);
// Rotate 1 degree
ctx.rotate(Math.PI/180);
// Move registration point back to the top left corner of canvas
ctx.translate(-ball.x, -ball.y);
//draw the ball
//restore canvas back to original state
ctx.restore();
// Update the y location.
ball.y += yvel;
ball.x += xvel;
//put repeatme function into the animation frame and store it in animate
animate = window.requestAnimationFrame(repeatme);
//condition take into account the radius of the ball so
//it bounces at the edge of the canvas instead
//of going off of the screen to its center point.
if(ball.y >= canvas.height - ball.r){
//window.cancelAnimationFrame(animate);
yvel = yvel *-1;
}else if(ball.y <= ball.r){
yvel = yvel /-1;
}
if(ball.x >= canvas.width- ball.r){
xvel = xvel *-1;
}else if(ball.x <=ball.r){
xvel = xvel/-1;
}
}
// Get the animation going.
repeatme();
</script>
</body>
</html>