Home/ Questions/Q 6780751
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-26T16:32:35+00:00

Its my first time here and I don’t know how to indent this sorry

  • 0

Its my first time here and I don’t know how to indent this sorry :/

I have an image of a van and I am trying to move it across the screen to as if it is driving.
Once that is done I will scale the image to appear as if it is moving away (and getting smaller).

I need this to be done in standard javascript without any packages (such as JQuery) please.

What I’ve got is a van which for a reason I can’t break down is moving along 2 paths instead of one. Also moving in the wrong direction (it should move along the path y=-25x so that every 25 pixels moved to the right it should move 1 pixel upwards).

To illustrate what I am trying to achieve, please see this image:
https://i.stack.imgur.com/9WIfr.jpg

This is my javascript file:

var viewWidth = 800;        
var viewHeight = 480;        
var fps = 30;        
var delay = getFrame(fps);        
var vanWidth, vanHeight, vanObj;   

function initVan() {        
  vanObj = document.getElementById("van");        
  vanObj.style.position = "absolute";        
  vanObj.src = "pics/delivery/van.png";        
  vanWidth = 413;        
  vanHeight = 241;        
  var startX = 0-vanWidth;        
  var startY = viewHeight-vanHeight;        
  setPosition(startX,startY);        
  transition(startX,startY,3000);        
}

function transition(startX,startY,time) {        
  //the intention of this is to follow a path y=-25x in mathematical terms
  var endX = viewWidth;        
  var endY = startY-(endX/-25);        
  //note that this is the velocity per millisecond
  var velocityX = (endX-startX)/time;        
  var velocityY = (endY-startY)/time;        
  alert(endY+", "+startY);        
  move(velocityX,velocityY,endX,endY);        
}

function move(vX,vY,eX,eY) {        
  var posX = getX();        
  var posY = getY();        
  if (posX<=eX || posY<=eY) {        
    //velocityX (in milliseconds) * delay = the amount of pixels moved in one frame @fps=30
    var moveX = vX*delay;        
    var moveY = vY*delay;        
    var newX = posX+moveX;        
    var newY = posY+moveY;        
    setPosition(newX,newY);        
    setTimeout(function() {        
        move(vX,vY,eX,eY);        
    }, delay);        
  }        
} 


function getX() {        
  return vanObj.offsetLeft;        
}    

function getY() {        
  return vanObj.offsetTop;        
}  

function setPosition(newX,newY) {        
  vanObj.style.left = newY + "px";        
  vanObj.style.top = newX + "px";        
}        

function setSize(scaleX,scaleY) {        
  vanWidth *= scaleX;        
  vanHeight *= scaleY;        
  vanObj.width = vanWidth;        
  vanObj.height = vanHeight;        
}      

function getFrame(fps) {        
  return Math.floor(1000/fps);        
}

This is my HTML file:

<script type="text/javascript" src="delivery.js"> </script>
<body onLoad="initVan();">
<img id="van" width=413 height=241/>

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    Unless you have a no-libraries requirement, or particularly enjoy reinventing the wheel, I’d solve this using jQuery’s effects library, and in particular .animate: http://api.jquery.com/animate/. See the first example on that page.

    $(document).ready(function() {
  $('#van')
    .attr({
      width: 413,
      height: 241  //etc.
    })
    .animate({
      width: "70%",
      height: "70%"  //etc.
  }, 3000);
});

    Less code means less maintenance. Means happy customer.

    • 0