• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
JackBid

Can anyone work out what is wrong with this code?

4 posts in this topic

Hi, I am working on and html5 javascript game, and I recently just added keyboard input. The concept is that whenever and arrow key is pressed, it updates the position of the shape in the html5 canvas. I thought it was working fine, however after testing, the shapes seem to have some velocity to them, when you hold down the arrow key they seem to pick up speed. I am still new to game development, so it may just be a stupid mistake on my part. Here is the code:

 

 

<!DOCTYPE html>
 
<html>
<head>
<title>Making things move</title>
<meta charset="utf-8">
 
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
 
<style type="text/css">
canvas
{
border: 2px solid gray;
background-color: black;
}
</style>
 
<script type="text/javascript">
$(document).ready(function() {
var canvas = $("#myCanvas");
var context = canvas.get(0).getContext("2d");
 
var canvasWidth = canvas.width();
var canvasHeight = canvas.height();
 
var x = 0;
var y = 0;
 
var xWidth = 30;
var yHeight = 30;
 
function MoveLeft(){
x -= 1;
};
function MoveUp(){
y -= 1;
};
function MoveRight(){
x += 1;
};
function MoveDown(){
y += 1;
};
 
 
function GameLoop(){
 
window.addEventListener('keydown', function(event) {
  switch (event.keyCode) {
 
  case 37: 
  MoveLeft();
  break;
 
    case 38: 
      MoveUp();
    break;
 
    case 39: 
    MoveRight();
    break;
 
    case 40: 
      MoveDown();
    break;
  }
}, false);
 
if(x + xWidth >= canvasWidth){
x = canvasWidth - xWidth;
}else if(x <= 0){
x = 0;
}
 
if(y + yHeight >= canvasHeight){
y = canvasHeight - yHeight;
}else if(y <= 0){
y = 0;
}
 
context.clearRect(0, 0, canvasWidth, canvasHeight);
context.fillStyle="rgb(238, 64, 0)";
context.fillRect(x, y, xWidth, yHeight);
 
setTimeout(GameLoop, 33);
};
 
GameLoop();
 
 
 
});
</script>
</head>
 
<body>
<canvas id="myCanvas" width="800" height="500">
<!-- Insert fallback content here -->
</canvas>
</body>
</html>
 
Just to further explain what is going on, the game loop is running every 33 milliseconds and when it does that it clears the entire canvas and then draws a new one based on the x and y variables which increase or decrease based on the keyboard input.
0

Share this post


Link to post
Share on other sites
If I read this correctly, you add a new key handler every frame. This means that after 3 frames, you'll handle every key press 3 times.

I think this was the problem, thank you very much!

0

Share this post


Link to post
Share on other sites

You could further simplify your code by making a simple line change

 

  Case 37 : X-=1; // MoveLeft

 

So on and So Forth

0

Share this post


Link to post
Share on other sites

you can also do your boundaries inside your movement functions with if statements. 

EX:

moveDown()

if (y+1 < canvasHeight()  {y+=1;}

 

It will take out several unnecessary lines of code. :P

0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0