Functions

function loadImage(url,framesWide,framesHigh);

Loads an image from the place specified by url.

   var picture;
   picture = loadImage("smile.png");

Will load the file "smile.png" from the same folder as the program and place it in the variable named picture

You may also use full url paths.

   var logo;
   logo = loadImage("http://www.google.com/images/logos/ps_logo2.png");

Will load the Google logo from google.com and place it in the variable named logo.

You may optionally specify framesWide and framesHigh values if you have a multiple frame animation in a single image. These are called SpriteSheets.

   var runner;
   runner = loadImage("http://www.thebest3d.com/pda/tutorials/array2animation/walksequence_spritesheet.png",5,5);

This code will download a 25 frame animation of a runner stored as a set of images evenly spaced 5 across and 5 down.

function drawImage(image,x,y,frame,angle);

Draws an image that has been loaded with loadImage.

The simplest form is:

   drawImage(picture,10,20);

In addition to the simple form you may also choose a frame from an animation

   drawImage(runner,200,300,5);

Animation frames are numbered from zero so the 25 frame runner animation uses frame numbers 0-24;

You may also rotate the image

   drawImage(logo,400,200,0,9.5);

This will draw the logo at 400,200 rotated by 9.5; Since the logo is not an animation, it only has a frame 0;

function keyIsDown(keycode);

Tests to see if a key is currently held down. The keycode is a number, for example the keycodes for the cursor keys are 37,38,39,40 for left,up,right,down respectively.

The following example reduces y by 1.5 if the up key is being held down.

  if ( keyIsDown(38) ) {
    y=y-1.5;
  }

function keyWentDown(keycode);

keyWentDown works the same as keyIsDown only it tests to see if the key has gone from unpressed to pressed.

It is possible to have keyIsDown() return false and keyWentDown() return true if someone pressed and released a key extremely quickly.