I am new to javascript games.
I have an idea of game, As an example if I am taking Solidsnake's character.
I want character view changes on pressing navigation keys.
If I press left key it should show left view, right key for right view and so on.
How do i get change in image on pressing keys , how can I do this in javascript?
Idea of game-
Code in brief-
var leftKey,upKey,rightKey,downKey;
var box = $("#plane"),
left = 37,
up = 38,
right = 39,
down = 40;
function key(e) {
console.log(e.keyCode);
var $key = e.keyCode;
$(document).keydown(function(e) {
if (e.keyCode == left)
leftKey = true;
if (e.keyCode == up)
upKey = true;
if (e.keyCode == right)
rightKey = true;
if (e.keyCode == down)
downKey = true;
}).keyup(function(e) {
if (e.keyCode == left)
leftKey = false;
if (e.keyCode == up)
upKey = false;
if (e.keyCode == right)
rightKey = false;
if (e.keyCode == down)
downKey = false;
});
}
$("body").keydown(function(){
key(event);
});
setInterval(function() {
if (upKey) {
box.css("top", "-=10");
}
if (rightKey) {
box.css("left", "+=10");
}
if (downKey) {
box.css("top", "+=10");
}
if (leftKey) {
box.css("left", "-=10");
}
},20);
Right now i have this code with simple navigation moves.
Js fiddle
You can do this with CSS to set it right and avoid multiple image requests. You need to have a sprite with all images of the character in a row and then mask with a div the area you need to show. Then with javascript you can change the position of the image either by using marginLeft or marginRight or left and right (you need to set position relative or absolute for left and right).
When you do e.keyCode == up and the like, you can change the image source then:
if (e.keyCode == up) {
upKey = true;
$("#plane").attr('src', 'up-img-src');
}
Either do this: http://jsfiddle.net/VMM5P/1/
Change the image src on keypress:
if (upKey) {
box.attr("src", "http://cdn3.iconfinder.com/data/icons/blackblue/128/iChat.png");
}
if (rightKey) {
box.attr("src", "http://cdn2.iconfinder.com/data/icons/blackblue/128/guitar.png");
}
if (downKey) {
box.attr("src", "http://cdn3.iconfinder.com/data/icons/blackblue/128/TextEdit.png");
}
if (leftKey) {
box.attr("src", "http://cdn2.iconfinder.com/data/icons/blackblue/128/preview.png");
}
or you can make a sprite and position them accordingly:
Suppose box is the div which has a background sprite image
if (upKey) {
box.css("background-position", "0px 0px"); // pos 1
}
if (rightKey) {
box.css("background-position", "120px 0px"); // pos 2
}
if (downKey) {
box.css("background-position", "240px 0px"); // pos 3
}
if (leftKey) {
box.css("background-position", "360px 0px"); // pos 4
}
You would want to change the attr source for the image.
if (leftKey) {
box.find('img').attr('src', 'ENTER NEW IMAGE URL HERE');
}
Related
I am trying to control a Sprite using the arrow keys (UP/DOWN for Translation & LEFT/RIGHT for Rotation).
I need the sprite to translate in the direction it has been rotated in.
The issue is that when the sprite is rotated after the sprite has been translated, the position of the sprite resets to where it was originally. I have tried using one div for rotation and one div for translation to no success.
The problem I am facing is a little different to the usual "moving div around screen" issue because I need to move the div at angles and continue to move at that angle.
I feel I am overlooking a simple solution, I would really appreciate if someone could point me in the right direction! Is there an easier alternative to what I am attempting to do that someone could make me aware of?
I have created a JSFiddle to demonstrate what is going on:
CSS transform sprite fiddle
var r = document.getElementById("image2");
document.addEventListener("keyup", checkKeyUp);
document.addEventListener("keydown", checkKey);
var trany = 0;
var rotate = 0;
function checkKey(e) {
e = e || window.event;
if (e.keyCode == '38') {
// up arrow
trany = trany-1;
r.style.transform = 'rotate('+rotate+'deg)translateY('+trany+'vmin)';
}
else if (e.keyCode == '40') {
// down arrow
trany = trany+1;
r.style.transform = 'rotate('+rotate+'deg)translateY('+trany+'vmin)';
}
else if (e.keyCode == '37') {
// left arrow
rotate = rotate-.8;
r.style.transform = 'translateY('+trany+'vmin)rotate('+rotate+'deg)';
}
else if (e.keyCode == '39') {
// right arrow
rotate = rotate+.8;
r.style.transform = 'translateY('+trany+'vmin)rotate('+rotate+'deg)';
}
}
function checkKeyUp(e) {
e = e || window.event;
if (e.keyCode == '38') {
// up arrow
}
else if (e.keyCode == '40') {
// down arrow
}
else if (e.keyCode == '37') {
// left arrow
r.style.transform = 'translateY('+trany+'vmin)rotate('+rotate+'deg)';
}
else if (e.keyCode == '39') {
// right arrow
r.style.transform = 'translateY('+trany+'vmin)rotate('+rotate+'deg)';
}
}
#myAnimation {
top:250px;
left:250px;
position: absolute;
}
#image2 {
width:40%
}
img {
width: 30%;
}
<!DOCTYPE html>
<html>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<body>
<div id ="myContainer">
<div id="image1" style="height:300px;width:500px; background-
color:red;"></div>
</div>
<div id ="myAnimation">
<image id="image2" src="https://banner2.kisspng.com/20180415/pge/kisspng-arrow-desktop-wallpaper-symbol-clip-art-up-arrow-5ad37ddc82f384.4572004515238097565364.jpg" style="bottom:0px;width:10%"></image>
</div>
</body>
</html>
what you want to achieve is to move your element independently from its previous state and this cannot be achieved using only transform since transform always consider the initial state in order to move your element.
An idea is to consider using bottom/left to move the element and use only transform to rotate the element. The angle of rotation will define how you will adjust the bottom and left properties:
var r = document.getElementById("image2");
document.addEventListener("keydown", checkKey);
var rotate = 0;
var left=0;
var bottom= 0;
function checkKey(e) {
e = e || window.event;
if (e.keyCode == '38') {
// up arrow
r.style.left = left + Math.sin(rotate*Math.PI/180) + 'px';
r.style.bottom = bottom + Math.cos(rotate*Math.PI/180) + 'px';
} else if (e.keyCode == '40') {
// down arrow
r.style.left = left - Math.sin(rotate*Math.PI/180) + 'px';
r.style.bottom = bottom - Math.cos(rotate*Math.PI/180) + 'px';
} else if (e.keyCode == '37') {
// left arrow
rotate = rotate - .8;
r.style.transform = 'rotate(' + rotate + 'deg)';
} else if (e.keyCode == '39') {
// right arrow
rotate = rotate + .8;
r.style.transform = 'rotate(' + rotate + 'deg)';
}
left = parseFloat(r.style.left);
bottom = parseFloat(r.style.bottom);
}
#image2 {
width: 40px;
position: absolute;
}
<img id="image2" src="https://banner2.kisspng.com/20180415/pge/kisspng-arrow-desktop-wallpaper-symbol-clip-art-up-arrow-5ad37ddc82f384.4572004515238097565364.jpg" style="left:0;bottom:0;">
To fix this problem we need to understand how transform works. It does each step one by one. If we want, for example to move diagonally, first we need to rotate, then translate. If we want to make the next move, our previous steps need to be saved. If we don't remember them, the arrow will be animated from the beginning.
So, on each animation end (key up) we need to save all the previous steps.
The next step is all the previous steps + translate/rotate.
Here is your code that I think is working correctly:
var r = document.getElementById("image2");
document.addEventListener("keyup", checkKeyUp);
document.addEventListener("keydown", checkKey);
var saved_moves = '';
var trany = 0;
var rotate = 0;
function checkKey(e) {
e = e || window.event;
if (e.keyCode == '38') {
// up arrow
trany = trany-1;
r.style.transform = saved_moves + 'translateY('+trany+'vmin)';
}
else if (e.keyCode == '40') {
// down arrow
trany = trany+1;
r.style.transform = saved_moves + 'translateY('+trany+'vmin)';
}
else if (e.keyCode == '37') {
// left arrow
rotate = rotate-2;
r.style.transform = saved_moves + 'rotate('+rotate+'deg)';
}
else if (e.keyCode == '39') {
// right arrow
rotate = rotate+2;
r.style.transform = saved_moves + 'rotate('+rotate+'deg)';
}
}
function checkKeyUp(e) {
e = e || window.event;
if (e.keyCode == '37' || e.keyCode == '38' || e.keyCode == '39' || e.keyCode == '40') {
// every arrow
saved_moves = r.style.transform;
// reset trany and rotate values
trany = 0;
rotate = 0;
}
}
You can check this jsfiddle https://jsfiddle.net/cyv0j1du/49/
EDIT
Becouse the solution above would create a very long transform, I've came up with different solution. When you release the key, app is reading the matrix value, and then it changes the arrow top and left value. Now only rotate value is remembered.
// Based on the absolute position you've chosen
var left = 250;
var top = 250;
function checkKeyUp(e) {
e = e || window.event;
if (e.keyCode == '37' || e.keyCode == '38' || e.keyCode == '39' || e.keyCode == '40') {
var matrix = window.getComputedStyle(r).getPropertyValue('transform');
matrix = matrix.slice(0, -1);
var values = matrix.split(',');
var x = values[4];
var y = values[5];
top += parseInt(y);
left += parseInt(x);
r.style.top = top + 'px';
r.style.left = left + 'px';
r.style.transform = 'rotateZ('+rotate+'deg)';
trany = 0;
}
}
I've also deleted #myAnimation
#image2 {
width: 20%;
position: absolute;
top: 250px;
left: 250px;
}
so I've deleted the div
<image id="image2" src="https://banner2.kisspng.com/20180415/pge/kisspng-arrow-desktop-wallpaper-symbol-clip-art-up-arrow-5ad37ddc82f384.4572004515238097565364.jpg" style="bottom:0px;width:10%"></image>
You can check how it works here:
https://jsfiddle.net/w1ox240m/57/
I have element
<div id="square"></div>
He has a property to move on document
var square = document.getElementById("square");
document.body.onkeydown = function(e) {
if (e.keyCode == 37) {left()}
if (e.keyCode == 38) {up()}
if (e.keyCode == 39) {right()}
if (e.keyCode == 40) {down()}
}
How I make a function, which not allowed movement, if square element is closest to document border?
JSFiddle: https://jsfiddle.net/zutxyLsq/
You need to check if left is outside of boundaries like this:
function left() {
console.log('Left');
var left = parseInt(square.style.left || getComputedStyle(square)['left'], 10);
if (left >= 50) {
square.style.left = (left - 50) + 'px';
}
}
function right() {
console.log('Right');
var left = parseInt(square.style.left || getComputedStyle(square)['left'], 10);
if (left+50+square.offsetWidth < window.innerWidth) {
square.style.left = (left + 50) + 'px';
}
}
https://jsfiddle.net/zutxyLsq/3/
and the same for up and down.
I am trying to move an image when the keys w, a, s, and d are pressed, but nothing is happening, and nothing is showing up in the console. Any help or suggestions would be greatly appreciated.
var moveBy = 10;
function moveObj(name, xPix, yPix)
{
var obj = document.getElementById(name);
var xp = parseInt(obj.style.left) + xPix;
var yp = parseInt(obj.style.top) + yPix;
obj.style.left = xp;
obj.style.top = yp;
}
$(document).ready(function()
{
$('body').keydown(function(e)
{
if(e.keyCode == 68)
{
moveObj('player', moveBy, 0);
}
else if(e.keyCode == 65)
{
moveObj('player', -moveBy, 0);
}
else if(e.keyCode == 87)
{
moveObj('player', 0, -moveBy);
}
else if(e.keyCode == 83)
{
moveObj('player', 0, moveBy);
}
});
});
Did you set position: relative on your player object?
That will be needed to move the player. If you have it set to static, it'll not move.
put this in moveObj to see if it's actually being called: console.log(arguments);. Set the new value with the units, i.e. obj.style.left = xp + 'px';. Also make sure the element you're changing the position of has a position property, you're probably looking for position: absolute;. Adding the HTML to your post would help.
I tried to make a moving img, and it works partially. If I press the right, up or down button, it moves right, up or down. But, if I press the left button, it jumps very fast very far to the right, and then back to the left and doesn't stop moving (I believe. I said it was fast).
JSFiddle;
Javascript:
$(document).ready(function() {
var up = down = left = right = false;
var top = 100, left = 500;
$("body").on("keydown", function(e) {
if(e.keyCode == 39) {e.preventDefault(); if (right == false) right = setInterval(moveRight, 80);}
else if(e.keyCode == 37) {e.preventDefault(); if (left == false) left = setInterval(moveLeft, 80);}
else if(e.keyCode == 38) {e.preventDefault(); if (up == false) up = setInterval(moveUp, 80);}
else if(e.keyCode == 40) {e.preventDefault(); if (down == false) down = setInterval(moveDown, 80);}
});
$("body").on("keyup", function(e) {
if(e.keyCode == 39) {clearInterval(right); right = false;}
else if(e.keyCode == 37) {clearInterval(left); left = false;}
else if(e.keyCode == 38) {clearInterval(up); up = false;}
else if(e.keyCode == 40) {clearInterval(down); down = false;}
});
function moveUp() {
top -= 2;
$("#player").css("top", top + "px");
}
function moveDown() {
top += 2;
$("#player").css("top", top + "px");
}
function moveLeft() {
left -= 2;
$("#player").css("left", left + "px");
}
function moveRight() {
left += 2;
$("#player").css("left", left + "px");
}
});
This is probably not the best way to do this, I'm open for better suggestions.
You're defining two "left" variables, and they are getting in the way of each other. Change one of their names (perhaps leftInterval for the interval variable), and things should go better.
The variables are overwritten, try something like :
$("body").on("keydown", function(e) {
e.preventDefault();
var elm = $("#player"),
top = parseInt(elm.css('top')),
left = parseInt(elm.css('left'));
switch(e.which) {
case 37:
elm.css("left", left-2);
break;
case 38:
elm.css("top", top-2);
break;
case 39:
elm.css("left", left+2);
break;
case 40:
elm.css("top", top+2);
break;
}
});
FIDDLE
I am currently doing this for input handling:
var upKey = false;
var downKey = false;
var leftKey = false;
var rightKey = false;
var sqrt2over2 = 0.707106781;
var MoveSpeed = 20.0;
var Horizontal = false;
var Vertical = false;
document.onkeyup=function(e){
if(e.which == 87)
{
Vertical = false;
upKey = false;
}
if(e.which == 83)
{
Vertical = false;
downKey = false;
}
if(e.which == 65)
{
Horizontal = false;
leftKey = false;
}
if(e.which == 68)
{
Horizontal = false;
rightKey = false;
}
}
document.onkeydown=function(e){
//Up arrow key
if(e.which == 87) upKey = true;
//Down arrow key
if(e.which == 83) downKey = true;
//Left arrow key
if(e.which == 65) leftKey = true;
//Right arrow key
if(e.which == 68) rightKey = true;
var diagonals = Vertical && Horizontal;
if(downKey)
{
Vertical = true;
moveY -= diagonals ? MoveSpeed * sqrt2over2: MoveSpeed;
}
if(upKey)
{
Vertical = true;
moveY += diagonals ? MoveSpeed * sqrt2over2: MoveSpeed;
}
if(rightKey)
{
Horizontal = true;
moveX -= diagonals ? MoveSpeed * sqrt2over2: MoveSpeed;
}
if(leftKey)
{
Horizontal = true;
moveX += diagonals ? MoveSpeed * sqrt2over2: MoveSpeed;
}
}
I need to have this work so that the screen doesn't pause at all when you press another direction or multiple directions. Currently there is a bit of a pause. Is there a setting to turn off this pause or is there another approach to pooling and responding to input which circumvents this dilemma?
I think the pause is due to key repeat rate. Take a look at this question / answers: remove key press delay in javascript
The problem is that you're using the operating system's key repeat as the 'tick' for moving. Instead of this you should use setInterval to create your own tick for moving, and then monitor keydown / keyup to change the direction of movement.