I am trying to learn JavaScript and I am wondering whether JavaScript has a event listener just like ActionScript's ENTER_FRAME. Basically, I want this event listener to listen "all the time" not just wait for any particular instance (mouse click, keyboard event) of event.
This would probably be worth a look too :
http://paulirish.com/2011/requestanimationframe-for-smart-animating/
You're looking for setInterval(func, time). In the case of making it work like ENTER_FRAME, then you would make time very small. So, if you wanted to imitate a frame rate of say, 30 times a second:
// you will need to make sure you have good scoping around the function param.
setInterval(function(){console.log('enterframe')}, 33)
// 33 is about 1000 milliseconds / 30.
Actually, setInterval is in Flash too -- flash.utils.setInterval.
As a side note -- unfortunately, setInterval (in both Flash and JS) can work against the native refresh rate. In Flash ENTER_FRAME avoids this -- you render when the swf re-renders. In the browser, well, setInterval simply can't do that.
HTML5 provides access to the requestAnimationFrame()
<canvas id="canvas" width="400" height="400"></canvas>
<script>
window.onload = function () {
var canvas = document.getElementById('canvas'),
context = canvas.getContext('2d'),
var counter = 0;
(function drawFrame () {
window.requestAnimationFrame(drawFrame, canvas);
context.clearRect(0, 0, canvas.width, canvas.height);
console.log(counter++);
// animation code goes here
}());
};
</script>
Credit goes to Keith Peters for helping sort this out. Highly recommend his book 'HTML5 animation with Javascript' by FriendsOfEd:
http://www.apress.com/9781430236658
I am still learning how to convert AS3 to JavaScript, but would it not be this function:
createjs.Ticker.addEventListener("tick", gameLoop);
gameLoop is the custom function that will be called on every 'tick'.
Check out this helpful example of writing a game in Adobe Animate CC using JavaScript instead of AS3: https://software.intel.com/en-us/html5/hub/blogs/flash-cc-to-html5
Nope. Not really. A good substitute would be setInterval or setTimeout:
function doAllTheTime() { }
function wrapper() {
doAllTheTime();
setTimeout(wrapper, 40);
}
wrapper();
But even then, you're pretty limited, because you don't have access to any of the event object properties.
Related
First of all, hello.
I have to develop a simple game in flash, usign HTML5 Canvas and JavaScript. The game, however poor, is pretty much implemented. My problem is, that after you play the game, it shows a try again button, designed to go back to frame 1. When i click the button it goes to frame 1 and returns to frame 25. Any ideas?
The last frame has this code:
var root = this;
this.stop();
this.tryAgain_btn.addEventListener("click", mouseClickHandler);
function mouseClickHandler(e) {
root.gotoAndPlay(0);
};
And frame one has this code:
var self = this;
this.stop();
this.play_btn.addEventListener("click", go);
function go()
{
self.gotoAndPlay(1);
}
Any ideas on how to solve this? Thank you.
Are you developing this in html5 or in actionscript? Based on your picture of your timeline it looks like you're using actionscript, not a HTML5 Canvas with javascript.
Besides that, try using gotoAndStop(1); rather than gotoAndPlay(0) and removing your stop(); methods. Let me know in the comments if it works but since your question is slightly unclear I don't have a grasp on what you're doing.
EDIT
Example, in case you don't understand:
var root = this;
this.stop();
this.tryAgain_btn.addEventListener("click", mouseClickHandler);
function mouseClickHandler(e) {
root.gotoAndStop(1);
}
EDIT 2
Take a shot at using
this.tryAgain_btn.addEventListener("click", function (event)
{
this.gotoAndPlay(1);
});
I'm getting into game developing online. I am trying to make an online FPS game, and I've only gotten to the point where I need to update my character. I am trying to keep my code simple, using only a draw and update function. When the html loads, I execute both: (Is this necessary?)
<body onload='DRAW(); UPDATE();'>
The draw function draws the player to the screen, and the update is supposed to check for a keypress to move the character. I am trying to make the script update using this:
function UPDATE()
{
update = setInterval(UPDATE, 60);
}
and to my knowledge, it is working fine because when I try and edit code in my online IDE (c9.io) which I use to test the site, it freezes when the site is running. I am also calling eventListeners in the draw function. (Is this proper if I want to test for a key down every frame?)
function DRAW()
{
window.addEventListener('keydown', function (e) {
keys.keys = (keys.keys || []);
keys.keys[e.keyCode] = true;
});
window.addEventListener('keyup', function (e){
keys.keys[e.keyCode] = false;
});
}
My questions are:
Is there an easier way to make a script update every frame?
Is there a JavaScript addon (like Three.js) I can use to make
developing this easier on myself?
Any knowledge is greatly appreciated.
This makes everything crash:
function UPDATE()
{
update = setInterval(UPDATE, 60);
}
You are recursively creating a new interval every 60ms; the first time you call UPDATE, you create an interval that creates a new interval every 60ms. All newly create intervals do the same. Don't really know what you actually want to do here.
I am also calling eventListeners in the draw function. (Is this proper
if I want to test for a key down every frame?)
It's fine to create eventlisteners in the draw function, provided you only call this function once. Which I guess you don't. Each time you call DRAW() a new set of eventlisteners will be added, and you really don't want that.
What you need is a form of game loop. Explaining how to create an FPS game is a bit more than I can do, but you can start by looking at this article Anatomy of a video game
Is possible to translate in Javascript the auto-recall function draw() in Processing? How to simulate that behavior in JS?
There isn't a way Javascript on its own but if you download jQuery (https://jquery.com/) you are able to do something that works very similarly to the draw function in processing.
By using a piece of code similar to this you should be able to get a pretty good result:
setInterval(function() {
draw();
}, 1); //So it waits one millisecond untill calling the draw function
function draw() {
//Your code goes in here
}
I hope this works for you!
I am trying to create a draggable line in a graph via Flot. I have a function that accomplishes that and executes on Flot's Plothover event (which is similar to a mouseMove event) when a certain boolean is true. The function gets called continuously and this has caused the resulting animation to lag significantly. To solve this I tried two approaches:
First I tried using setTimeout. This helped the function run better, but I was unsatisfied. The animation began to lag again if the webpage was left open for more than a minute, I have no idea why. If anyone knows whats up with that any insight would be appreciated.
Second, I tried Underscore's throttle function. I am a little unsure of the syntax, and after some research and debugging this is what I settled on. The following code is inside the event handler:
var throttled1 = _.throttle(singleLine, 50);
throttled1(position);
Where singleLine is the following function, defined outside the event handler:
function singleLine(position) {
adjustLine1[0] = [position, Number.NEGATIVE_INFINITY];
adjustLine1[1] = [position, Number.POSITIVE_INFINITY];
graphData.push({ data: adjustLine1, lines: { show: true }, color: "gray" });
plot.setData(graphData);
plot.draw();
graphData.pop();
}
Keep in mind plot.draw() is a pretty long function (it redraws the entire graph). Anyway, it appears to work because singleLine is successfully called by throttled1(position). However, it is not improving performance at all. Am I using it correctly? Any other insights into how to make this run better are also welcomed. Thanks.
var throttled1 = _.throttle(singleLine, 50);
throttled1 must be initialized oustide of the event listener, so it can track calls and timers internally, event after event.
I know this question has been asked a lot of times, and I have seen the solutions to them on SO as well as other forums. Most of the times the solution suggested is to use Web Workers.
A game I'm developing requires me to run multiple functions at the same time. One of them is an on click function and other is a setInterval.
My approach at doing this can be seen here in this JSFiddle. (keep clicking in gray area to make player jump).
The whole idea is to continuously spawn those blue obstacles after an interval of 1000ms.
In my earlier approach the obstacles would spawn only when I click to make player jump, otherwise they wouldn't as expected.
How can I run such two functions side by side in order to achieve
the aim of spawning obstacles while also making player jump.
Secondly, what would be the best approach to carry out this process
in view of game development i.e attaining a certain level of
efficiency so that the animations are not affected.
Here is the HTML and Javascript code I've been working on:
<div class="container">
<div class="player"></div>
<div class="obstacle-container">
<div class="obstacle"></div>
</div>
</div>
$.fn.animator = function () {
var hit_list, done = false;
$(".container").click(function () {
if (!done) {
$(".obstacle").stop().animate({
left: "-=105%"
}, 10000, "linear");
$(".player").stop().animate({
bottom: "+=100px"
}, {
duration: 300,
complete: function () {
$(".player").animate({
bottom: "0"
}, 800);
},
step: function () {
//Test for collision
hit_list = $(".player").collision(".obstacle");
if (hit_list.length !== 0) {
$(function () {
if (!done) {
$(".container").append("Game Over!");
return false;
}
});
done = true;
}
}
});
}
});
};
$(function () {
$('.container').animator();
});
var interval = null;
$(".obstacle-container").obstacle_generator();
$.fn.obstacle_generator = function () {
interval = setInterval(function () {
$(".obstacle-container").append('<div class="obstacle"></div>');
}, 1000);
};
The generic concept you want to investigate is known as a game loop.
Almost every game will be built using some variant of this system:
Initialise game
Loop:
Check for user input
Update any actors
Draw the scene
Wait until it's time to repeat
A game running at 60 frames per second would perform this loop 60 times per second, or about once every 16ms.
Compared to your original question, you wouldn't need to be running multiple execution threads (running multiple functions together) to achieve this.
You are, in a way, already using a similar loop. jQuery maintains its own loop for updating animations. Where you are checking for collisions as part of your animation step, this is the sort of thing you would do in a hypothetical Player.update() method. You want to move this code out of jQuery, and in to a loop that you control.
Since you're running in a browser, the generic game loop becomes a bit more simple:
Check for user input - this can still be handled by event handlers, jQuery or not. Rather than directly changing properties like CSS position, though, they should act upon the state of the game object. For example, by changing the velocity of a Player object.
Update any actors - the important part of your loop. You should check how many milliseconds have passed since you last looped, since the browser doesn't guarantee that your code will be run exactly, or at least, 60 times per second. You should then loop through all of your game objects and update them all. In your Player.update() method, you would want to move it according to its velocity and the time passed, for example.
Draw the scene - if you're using DOM elements, then the browser handles drawing for you, of course. If you were using a <canvas> element, then you would do drawing yourself as part of the loop here.
Wait until it's time to repeat - this will be up to the browser to do for you, as part of normal setInterval/setTimeout behavior.
A simple game loop in JavaScript can look like this:
var gameObjects = [];
// Initialise game, create player objects etc, add them to the array
var gameLoop = function() {
// Loop through gameObjects, and call their respective update methods
};
setInterval(gameLoop, 16); // Try to run the loop 60 times per second.
In a complex game, you wouldn't have just a basic array to hold all game objects, this is just an basic example.