Javascript Moving an Image Left or Right Using Onscreen Buttons

Question

Ok I have been looking online to build a platformer and I am taking it step by step. I already have the images I need and how to place them onscreen. I also know how to do a point system but I am far from finished. Now I would like to know how to move a player left to right using onscreen buttons. What I am looking for is something totally different from this code I found here as it seems like too much code and it just moves characters to the right without stopping.

I am looking for:

1) 2 buttons right and left

2) press down on the button moves player in either right or left direction.

3) The player stops moving when you release the button.

// Other code
...
    imgObj.style.left = '0px'; 
}
function moveRight() {
    imgObj.style.left = parseInt(imgObj.style.left) + 1 + 'px';
}
function stop() {
    clearTimeout(animate);
    imgObj.style.left = '0px'; 
}
window.onload =init;
//-->
</script>
</head>
<body>
    <form>
        <img id="myImage" src="/images/html.gif" />
        <p>Click the buttons below to handle animation</p>
        <input type="button" value="Start" onclick="moveRight();" />
        <input type="button" value="Stop" onclick="stop();" />
    </form>
</body>
</html>

Answer 1

Here you go. Hope it's not too much code for you :)

The JSfiddle demo is here .

<head>
<style>
    #sprite { position:relative; } // needed for the img to be free to move around
</style>
<script>
    var timer_id; // reference of the timer, needed to stop it
    var speed = 50; // pixels/second
    var period = 40; // milliseconds
    var sprite; // the element that will move
    var sprite_speed = 0; // move per period
    var sprite_position = 100; // pixels


    function animate ()
    {
        sprite_position += sprite_speed;
        if (sprite_position < 0) sprite_position = 0;
        if (sprite_position > 200) sprite_position = 200;
        sprite.style.left = sprite_position+'px';
    }

    function move(direction)
    {
        if (timer_id) stop();
        sprite_speed = speed * period/1000 * direction;
        timer_id = setInterval (animate, period);
    }

    function stop()
    {
        clearInterval (timer_id);
        timer_id = null;
    }

    function init()
    {
       sprite = document.getElementById ("sprite"); // the HTML element we will move
       animate(); // just to initialize sprite position
    }

    window.onload =init; // start doing things once the page has loaded
</script>
</head>
<body>
    <img id="sprite" src="http://petiteleve.free.fr/SO/yoshi.png" />
    <p>Click the buttons below to handle animation</p>
    <input type="button" value="Left"  onmousedown="move(-1);" onmouseup="stop();"/>
    <input type="button" value="Right" onmousedown="move( 1);" onmouseup="stop();"/>
</body>

This is just a proof of concept.
You are still a long way from releasing Mario Bross 25, but that's a step in the right direction.
Or was it left?

Javascript Moving an Image Left or Right Using Onscreen Buttons

Question

1 answers

solution1
0 2014-01-05 06:40:10

Javascript Moving an Image Left or Right Using Onscreen Buttons

Question

1 answers

solution1 0 2014-01-05 06:40:10

solution1
0 2014-01-05 06:40:10