I am currently developing a Javascript game (almost everything is based on a tutorial yet, so I am not worried of sharing the code).
The problem is, I can't get the character to jump after pressing the Space button. Please, can someone look at the code and help me?
// EDIT: Sorry for lack of information I provided. The thing is - code is written, the game is in the state, that the character is animated (=is running) and the backgrounds are moving. Yesterday, I tried to implement some basic controls, such as jump by pressing spacebar. The thing is, the player won't jump at all, and browser console is not giving me any error statements.
Character is defined as Player on line 5. and 321. in the code provided below.
The jumping is defined in the following examples:
Pressing the Space button
var KEY_CODES = {
32: 'space'
};
var KEY_STATUS = {};
for (var code in KEY_CODES) {
if (KEY_CODES.hasOwnProperty(code)) {
KEY_STATUS[KEY_CODES[code]] = false;
}
}
document.onkeydown = function(e) {
var keyCode = (e.keyCode) ? e.keyCode : e.charCode;
if (KEY_CODES[keyCode]) {
e.preventDefault();
KEY_STATUS[KEY_CODES[keyCode]] = true;
}
};
document.onkeyup = function(e) {
var keyCode = (e.keyCode) ? e.keyCode : e.charCode;
if (KEY_CODES[keyCode]) {
e.preventDefault();
KEY_STATUS[KEY_CODES[keyCode]] = false;
}
};
Other jump information (please, read the comments in the code)
this.update = function() {
// jump, if the characted is NOT currently jumping or falling
if (KEY_STATUS.space && this.dy === 0 && !this.isJumping) {
this.isJumping = true;
this.dy = this.jumpDy;
jumpCounter = 12;
assetLoader.sounds.jump.play();
}
// longer jump if the space bar is pressed down longer
if (KEY_STATUS.space && jumpCounter) {
this.dy = this.jumpDy;
}
jumpCounter = Math.max(jumpCounter-1, 0);
this.advance();
// gravity
if (this.isFalling || this.isJumping) {
this.dy += this.gravity;
}
// change animation is-falling
if (this.dy > 0) {
this.anim = this.fallAnim;
}
// change animation is-jumping
else if (this.dy < 0) {
this.anim = this.jumpAnim;
}
else {
this.anim = this.walkAnim;
}
this.anim.update();
};
/**
* Update the Sprite's position by the player's speed
*/
this.update = function() {
this.dx = -player.speed;
this.advance();
};
/**
* Draw the current player's frame
*/
this.draw = function() {
this.anim.draw(this.x, this.y);
};
}
Player.prototype = Object.create(Vector.prototype);
Everything seems just fine to me, but the player just won't move. :(
Any help?
If you are curious about the full code, go here: http://pastebin.com/DHZKhBMT
EDIT2:
Thank you very much for your replies so far.
I have moved the RequestAnimFrame to the end of the function - will keep that in mind, thanks.
I have also implemented the simple jumping script Ashish provided above, but the character is still not jumping.
This is what it looks like now:
/** JUMP KEYS DEFINITION **/
$(document).keypress(function(e){
if(e.which==32){
$('Player.prototype').css({'top':"0px"});
}
setTimeout(function(){
$('Player.prototype').css({'top':"200px"});
},350);
});
/** DEFINING CHARACTER **/
function Player(x, y) {
this.dy = 0;
this.gravity = 1;
this.speed = 6;
this.jumpDy = -10;
this.isJumping = false;
this.width = 60;
this.height = 96;
this.sheet = new SpriteSheet('imgs/normal_walk.png', this.width, this.height);
this.walkAnim = new Animation(this.sheet, 4, 0, 11);
this.jumpAnim = new Animation(this.sheet, 4, 3, 3);
this.fallAnim = new Animation(this.sheet, 4, 3, 3);
this.anim = this.walkAnim;
Vector.call(this, x, y, 0, this.dy);
var jumpCounter = 0; // Maximalna dlzka drzania tlacidla skakania
}
Player.prototype = Object.create(Vector.prototype);
Where am I wrong?
I've tried in http://jsfiddle.net/Ykge9/1/
and you have an infinite loop in animate, the requestAnimFrame should be at the end of the function:
/**
* Loop cykly hry
*/
function animate() {
background.draw();
for (i = 0; i < ground.length; i++) {
ground[i].x -= player.speed;
ctx.drawImage(assetLoader.imgs.grass, ground[i].x, ground[i].y+250);
}
if (ground[0].x <= -platformWidth) {
ground.shift();
ground.push({'x': ground[ground.length-1].x + platformWidth, 'y': platformHeight});
}
player.anim.update();
player.anim.draw(64, 260);
requestAnimFrame( animate );
}
Related
The bug happens when you shoot and die at the same time, and in the console it pops up as "Uncaught TypeError: Cannot read property 'draw' of undefined. Line 65"
The thing is, the bug started happening when I included the function that kills the player, which starts on line 143, and the thing that breaks it is the single line
enemy = [];
Here's the enemy function
function Enemy(x, y) {
this.x = x;
this.y = y;
this.draw = function() {
noStroke();
fill(255, 0, 0);
rect(this.x, this.y, 20, 20);
}
this.move = function() {
this.x -= movement; }
this.offscreen = function() {
if(this.x < 0) {
return true;
} else {
return false;
}
}
this.contact = function() {
for(let i = 0; i < enemy.length; i++) {
var d = dist(playerx, playery, enemy[i].x, enemy[i].y);
if(d <= 20) {
this.kill();
}
}
}
this.kill = function() {
var prevScore = score;
playerx = width / 10;
playery = height / 2;
alert("You died! your score was: " + prevScore);
fire = [];
enemy = [];
score = 0
}
}
Here's where it says it's getting the type error (which worked perfectly before)
This is lines 55 - 74
for(let i = fire.length - 1; i > 0; i--) {
fire[i].draw();
fire[i].move();
fire[i].check();
if(fire[i].offscreen()) {
fire.splice(i, 1);
}
}
for(let i = enemy.length - 1; i > 0; i--) {
enemy[i].draw();
enemy[i].move();
if(enemy[i].offscreen()) {
enemy.splice(i, 1);
}
if(enemy[i].contact()) {
enemy[i].kill();
}
}
The entire code is here: https://code.sololearn.com/Wtza5vElEZ9d/?ref=app
(It's less than 200 lines so not really big)
As well as that bug, I am wanting to find out how it would be possible to make the game gradually get faster. I tried having the frameCount be divided/modulos by a variable (that I had called spawnRate) but when I altered the variable in any way, it just stopped spawning the squares all together.
It's also made with p5.js.
Your enemy.contact() function is used in if statement so you should return a boolean with that function.
this.contact = function() {
return dist(playerx, playery, this.x, this.y) <= 20;
}
It would be better if you make function death() in player object.
It will not be so confusing.
I am fairly new to JavaScript and have searched everywhere for an answer to my question and cant seem to find anything related at all. This tells me that I'm missing something with my understanding of how my program works.
I have written a small game where the player navigates through a randomly generated maze using a gameloop that checks keydown events every x milliseconds. The game has a difficulty dropdown menu and then the game is started my clicking a button that calls a function to create a canvas where the game is drawn.
My problem is that when the button is clicked again to create a new maze without reloading the page, the gameloop for the original maze is still running and so key events are registered twice. This is causing some unexpected behavior. It's as though every time the button is clicked, a new instance of the function is running. Is there some way that each time the button is clicked I can set it to stop the previous game function?
var canvas;
var div;
var mazeGenButton;
$(document).ready(function () {
canvas = null;
div = document.getElementById('canvascontainer');;
mazeGenButton = document.getElementById("mazeGenButton");
mazeGenButton.onclick = createInstance;
});
function createInstance() {
if (canvas != null) {
div.removeChild(document.getElementById("myCanvas"));
}
canvas = document.createElement('canvas');
canvas.id = "myCanvas";
canvas.width = 1000;
canvas.height = 1000;
div.appendChild(canvas);
drawMaze();
};
var drawMaze = function () {
//code here to create the game(not posted)
//here is the Key listener - not sure if it's related
var keyState = {};
window.addEventListener('keydown', function (e) {
keyState[e.keyCode || e.which] = true;
}, true);
window.addEventListener('keyup', function (e) {
keyState[e.keyCode || e.which] = false;
}, true);
function gameLoop() {
//left
if (keyState[37] || keyState[65]) {
if (isLegalMove(playerXPos - 1, playerYPos)) {
grid[playerXPos][playerYPos].removePlayerCell();
playerXPos -= 1;
grid[playerXPos][playerYPos].setPlayerCell();
}
}
//right
if (keyState[39] || keyState[68]) {
if (isLegalMove(playerXPos + 1, playerYPos)) {
grid[playerXPos][playerYPos].removePlayerCell();
playerXPos += 1;
grid[playerXPos][playerYPos].setPlayerCell();
}
}
//up
if (keyState[38] || keyState[87]) {
if (isLegalMove(playerXPos, playerYPos - 1)) {
grid[playerXPos][playerYPos].removePlayerCell();
playerYPos -= 1;
grid[playerXPos][playerYPos].setPlayerCell();
}
}
//down
if (keyState[40] || keyState[83]) {
if (isLegalMove(playerXPos, playerYPos + 1)) {
grid[playerXPos][playerYPos].removePlayerCell();
playerYPos += 1;
grid[playerXPos][playerYPos].setPlayerCell();
}
}
drawSurroundingCells();
setTimeout(gameLoop, 50);
}
}
I have a simple script where by I am trying to draw a circle when a mouse goes over the canvas and it takes about 2000 milliseconds, when the mouse leaves the canvas it then erases the circle.
I got most of it working - it draws the circle correctly, but the mouse out does not fully work as it keeps restarting.
This is my code:
canvas.addEventListener('mouseover',fill,false);
canvas.addEventListener('mouseout',erase, false);
function fill(){
circle.animate = true;
circle.direction = 1;
}
function erase(){
circle.animate = true;
circle.direction = 0;
}
function maths(){
if(circle.animate == true){
var amount = circle.vector * deltaTime;
if(circle.direction == 1){
circle.curAngle += amount;
}else if(circle.direction == 0){
circle.curAngle -= amount;
}
if(circle.curAngle % 2 == 0){
circle.curAngle = 0;
}
if(circle.curAngle == circle.endAngle){
circle.animate = false;
}
}
}
function draw(){
deltaTime = Date.now() - frame;
frame = Date.now();
maths();
context.clearRect(0,0,canvas.width,canvas.height);
context.beginPath();
context.arc(canvas.width/2, canvas.height/2, 100, circle.startAngle * Math.PI, circle.curAngle * Math.PI,false);
context.lineWidth = 2;
context.strokeStyle = 'blue';
context.stroke();
setTimeout(draw,1);
}
frames = Date.now();
draw();
I have made a fiddle of it too: http://jsfiddle.net/hru7xyfu/, to reproduce the error mouse over the canvas and wait for it to fully fill up then mouse out and you see the circle keeps restarting after it has fully erased it.
Where am i going wrong?
Try replacing
if(circle.curAngle == circle.endAngle){
circle.animate = false;
}
with:
if(circle.curAngle < circle.endAngle){
circle.curAngle = circle.endAngle
circle.animate = false;
}
if(circle.curAngle > circle.endAngle + 2){
circle.curAngle = circle.endAngle + 2
circle.animate = false;
}
The second if statement solves an issue where the circle grows too large (though you can't see it, because it starts overlapping itself)
Updated JSFiddle here:
http://jsfiddle.net/hru7xyfu/2/
I am trying to change the position of a circle inside a canvas using random x and y when hitting the space bar but i am stuck to figure out how I should implement a gravity effect so when the circle change it's position it come back down to the ground in a smoothy way
my jsfiddle :http://jsfiddle.net/seekpunk/efcnM/5/
how can i modify my update function to succeed my gravity effect
function update() {
$(window).keydown(function (e) {
var spacebarHit = e.which == 32 || e.keyCode == 32 ? true : false;
if (spacebarHit) {
Bluecircle.y -=1;// RandomPos;
Draw();
}
});
}
Why not use the real-world equations of motion?
if (spacebarHit) {
var oldPos = Bluecircle.y;
var u = 50;
var g = 9.81;
var t = 0;
var handle = setInterval(function () {
t++;
Bluecircle.y = oldPos-(((u)*t-(g/2)*t*t));
console.log(Bluecircle.y);
if (Bluecircle.y>oldPos) {
Bluecircle.y = oldPos;
clearInterval(handle);
}
}, 100);
Draw();
}
DEMO
Use Newtonian integration:
function mainLoop(dt) {
circle.acc.x = 0
circle.acc.y = 9.81 // positive is down
circle.vel.x += circle.acc.x * t
circle.vel.y += circle.acc.y * t
circle.pos.x += circle.vel.x * t
circle.pos.y += circle.vel.y * t
// check if the bottom of the screen has been hit, and
// clamp circle.poa to he within the world
// do bounces by flipping the sign of components of circle.vel
}
function jump() {
circle.vy = -20; // or something
}
I am building a simple 2D game as an attempt to learn canvas. The character can run around a virtual environment, and a variable called yOffset controls his offset from the top of the screen. I also have a global variable called running which sets itself to true or false based on whether or not the character is running (not shown here). My goal is to make the character bob up and down whilst he is running, and all the below code does is spawn lots of setInterval()s. Is this the right way to make my character run, or should I do it another way? If so, how?
$(document).keydown(function(e) {
if(e.which == 97) {
running = true;
run();
} else if(e.which == 100) {
running = true;
run();
} else if(e.which == 119) {
running = true;
run();
} else if(e.which == 115) {
running = true;
run();
}
});
(yes, if the character stops running, the running variable does go to false [not shown here] - I've already made sure the running variable works well)
runTimer = 0;
function run() {
if(runTimer == 0 && running) {
runTimer = 1;
yOffset = 80;
setTimeout(function() {
yOffset = 120;
}, 150);
setTimeout(function() { if (running) { runTimer = 0;run(); } }, 300);
}
}
If you need more information, the version that I am currently working on is available here.
I think you can simplify your code, and in fact you must in the quite probable case where you'd like to add some other characters.
To allow re-use of the animation, it's better to separate what is an animation (== the different steps that your character will go through), and an animation state (== in which step your character is now).
I wrote here some elements of an animation system.
So i define what is an animation step, a whole Animation (which is so far only an array of animation step), and an Animator (which holds the state, one might see it as a 'reader' of an animation).
Once you defined the animation and animators, and started the animators, you just have to call tick(time) to have the animation move on, and offset() to read the offset, which is way simpler than fighting with a bunch of setIntervals.
http://jsfiddle.net/xWwFf/
// --------------------
function AnimationStep(duration, offset) {
this.duration = duration;
this.offset = offset;
// you might add : image index, rotation, ....
}
// --------------------
function Animation(animationSteps) {
this.steps = animationSteps; // Array of AnimationStep
}
// define a read-only length property
Object.defineProperty(Animation.prototype, 'length', {
get: function () {
return this.steps.length
}
});
// --------------------
function Animator() {
this.currentAnimation = null;
this.step = -1;
this.running = false;
this.remainingTime = 0; // remaining time in current step;
}
Animator.prototype.startAnim = function (newAnim, firstStep) {
this.currentAnimation = newAnim;
this.step = firstStep || 0;
this.remainingTime = newAnim.steps[this.step].duration;
this.running = true;
}
Animator.prototype.tick = function (dt) {
// do nothing if no animation ongoing.
if (!this.running) return;
this.remainingTime -= dt;
// 'eat' as many frames as required to have a >0 remaining time
while (this.remainingTime <= 0) {
this.step++;
if (this.step == this.currentAnimation.length) this.step = 0;
this.remainingTime += this.currentAnimation.steps[this.step].duration;
}
};
Animator.prototype.offset = function () {
return this.currentAnimation.steps[this.step].offset;
}
// ______________________________
// example
var bounceAnim = [];
bounceAnim.push(new AnimationStep(200, 10));
bounceAnim.push(new AnimationStep(180, 20));
bounceAnim.push(new AnimationStep(150, 30));
bounceAnim.push(new AnimationStep(300, 40));
bounceAnim.push(new AnimationStep(320, 45));
bounceAnim.push(new AnimationStep(200, 40));
bounceAnim.push(new AnimationStep(120, 30));
bounceAnim.push(new AnimationStep(100, 20));
var anim1 = new Animation(bounceAnim);
var animator1 = new Animator();
var animator2 = new Animator();
animator1.startAnim(anim1);
animator2.startAnim(anim1, 3);
// in action :
var ctx = document.getElementById('cv').getContext('2d');
function drawScene() {
ctx.fillStyle = 'hsl(200,60%, 65%)';
ctx.fillRect(0, 0, 600, 200);
ctx.fillStyle = 'hsl(90,60%,75%)';
ctx.fillRect(0, 200, 600, 200);
ctx.fillStyle = 'hsl(10,60%,75%)';
ctx.fillRect(200, 200 + animator1.offset(), 22, 22);
ctx.fillStyle = 'hsl(40,60%,75%)';
ctx.fillRect(400, 200 + animator2.offset(), 22, 22);
animator1.tick(20);
animator2.tick(20);
}
setInterval(drawScene, 20);