I am making a battleship game with polar coordinates. After the user chooses two points, a battleship should be drawn in the middle. My Battleship constructor looks like this:
function Battleship(size, location, source){
this.size = size;
//initializing the image
this.image = new Image();
this.image.src = source;
this.getMiddlePoint = function(){
//get midpoint of ship
...
}
this.distanceBetween = function(t1, t2){
//dist between two points
}
this.display = function(){
var point = [this.radius];
point.push(this.getMiddlePoint());
point = polarToReal(point[0], point[1] * Math.PI / 12);
//now point has canvas coordinates of midpoint
var width = this.distanceBetween(this.info[0][0], this.info[this.info.length-1][0]);
var ratio = this.image.width / width;
ctx.drawImage(this.image, point[0] - width/2, point[1] - this.image.height / ratio / 2, width, this.image.height / ratio);
//draws the image
}
}
The display method of each ship gets called at a certain point (after the user has chosen the location). For some reason, the images do not show the first time I do this, but when I run this code at the very end:
for(var i = 0; i<playerMap.ships.length; i++){
playerMap.ships[i].display();
}
All ships are displayed correctly (not aligned well, but they are displayed). I think there is a problem with loading the images. I am not sure how to fix this. I tried using image.onload but I never got that to work. I also tried something like this:
var loadImage = function (url, ctx) {
var img = new Image();
img.src = url
img.onload = function () {
ctx.drawImage(img, 0, 0);
}
}
but the same problem kept happening. Please help me fix this problem. Here is the game in its current condition. If you place ships, nothing happens, but after you place 5 (or 10) ships, they suddenly all load.
EDIT:
I solved the problem by globally defining the images. This is still very bad practice, since I wanted this to be in the battleship object. This is my (temporary) solution:
var sub = [];
for(var i = 1; i<5; i++){
sub[i] = new Image();
sub[i].src = "/img/ships/battleship_"+i+".png";
}
I have a canvas for the game world and a canvas for the display screen. I also have a polygon with nodes V(x,y) to serve as a viewport that follows the player and his rotation. I would like to know how to clip from the game world along the polygon, rotate and draw to the smaller canvas.`
//main looping function
var requestAnimFrame = (function(){
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function(callback){
window.setTimeout(callback, 1000 / 60);
};
})();
//joystick setup
var leftManager = null;
var rightManager = null;
//precalculated math
var twoPi = Math.PI*2;
var halfPi = Math.PI/2;
var thirdOfCircleInRadians = twoPi/3;
//game canvas setup
var gameCvs = document.getElementById('gameCanvas');
gameCvs.width = 480;
gameCvs.height = 320;
//gameCvs.width - 960;
//gameCvs.height = 640;
var gameCtx = gameCvs.getContext("2d");
//game loop
var lastTime = 0;
function main() {
var now = Date.now();
var dt = lastTime==0? 0.016 : (now - lastTime) / 1000.0;
update(dt);
render(dt);
lastTime = now;
requestAnimFrame(main);
}
//collision class shorthand
var V = SAT.Vector;
var C = SAT.Circle;
var P = SAT.Polygon;
var R = new SAT.Response();
P.prototype.draw = function (ctx,type) {
ctx.save();
switch(type){
case 'van': ctx.fillStyle = "rgba(66, 66, 66, 0.5)"; break;
case 'col': ctx.fillStyle = "rgba(0, 0, 0, 1.0)"; break;
default: ctx.fillStyle = "rgba(0, 0, 0, 1.0)"; break;
}
ctx.translate(this.pos.x, this.pos.y);
ctx.beginPath();
var points = this.calcPoints;
ctx.moveTo(points[0].x, points[0].y);
var i = points.length;
while (i--) ctx.lineTo(points[i].x, points[i].y);
ctx.closePath();
//stroke to see through camera, when camera is not drawn use fill
ctx.stroke();
//ctx.fill();
ctx.restore();
};
//first for collisions, second for vanity. first is black, second is grey
var O = function(colPolygon,vanPolygon){
this.colPolygon = colPolygon;
this.vanPolygon = vanPolygon;
this.visible = false;
};
var objectVendor = function(type,position){
switch(type){
case 'tree':
return new O(new P(position,[
new V(10.5,19.5),
new V(20.5,9.5),
new V(23,-4),
new V(15,-16.5),
new V(-4,-19.5),
new V(-18,-14.5),
new V(-23,-0.5),
new V(-18.5,14.5),
new V(-8,20)
]),new P(position,[
new V(21,39),
new V(41,19),
new V(46,-8),
new V(30,-33),
new V(-8,-39),
new V(-36,-29),
new V(-46,-1),
new V(-37,29),
new V(-16,40)]));
break;
default: return false; break;
}
return false;
}
//Camera and Player Polygons
var cameraPoly = new P(new V(0,0),[
new V(-240,-160),
new V(240,-160),
new V(240,160),
new V(-240,160)
]);
var player = new P(new V(0,0),[
new V(5,2.5),
new V(7.5,2),
new V(7.5,-2),
new V(5,-2.5),
new V(-5,-2.5),
new V(-7.5,-2),
new V(-7.5,2),
new V(-5,2.5)
]);
//players start position on the screen, and starting angle, init velocity
player.pos = new V(240,160);
player.setAngle(1);
//players velocity for movement
player.vel = new V(0,0);
var world = {
objects: [],
visibleObjects: [],
worldCvs: null,
worldCtx: null,
init: function(){
//set up world canvas
this.worldCvs = document.createElement('canvas');
this.worldCvs.width = 480;
this.worldCvs.height = 480;
this.worldCtx = this.worldCvs.getContext("2d");
//populate world with stuff
this.objects.push(objectVendor('tree',new V(100,100)));
this.objects.push(objectVendor('tree',new V(150,200)));
this.objects.push(objectVendor('tree',new V(75,300)));
},
update: function(dt){
this.visibleObjects = [];
cameraPoly.setAngle(player.angle);
//cameraPoly.pos = player.pos;
cameraPoly.pos = new V(player.pos.x+(110*Math.cos(player.angle+halfPi)),player.pos.y+(110*Math.sin(player.angle+halfPi)));
//update objects to mark if they are in view
var i = this.objects.length;
while(i--){
if(SAT.testPolygonPolygon(this.objects[i].vanPolygon, cameraPoly, R)){
this.visibleObjects.push(this.objects[i]);
}
}
//}
},
draw: function(dt){
this.worldCtx.setTransform(1,0,0,1,0,0);
this.worldCtx.clearRect(0,0,this.worldCvs.width,this.worldCvs.height);
player.draw(this.worldCtx);
var i = this.visibleObjects.length;
while(i--){
this.visibleObjects[i].colPolygon.draw(this.worldCtx,'col');
this.visibleObjects[i].vanPolygon.draw(this.worldCtx,'van');
}
//for testing
cameraPoly.draw(this.worldCtx);
/*
this.worldCtx.save();
this.worldCtx.beginPath();
var i = cameraPoly.calcPoints.length;
this.worldCtx.moveTo(cameraPoly.calcPoints[0].x,cameraPoly.calcPoints[0].y);
while(i--){
this.worldCtx.lineTo(cameraPoly.calcPoints[i].x,cameraPoly.calcPoints[i].y);
}
this.worldCtx.clip();
this.worldCtx.restore();
*/
}
}
function render(dt){
gameCtx.setTransform(1,0,0,1,0,0);
gameCtx.clearRect(0,0,gameCvs.width,gameCvs.height);
world.draw();
//gameCtx.save();
//gameCtx.translate(cameraPoly.pos.x,cameraPoly.pos.y);
//gameCtx.translate(gameCtx.width/2,gameCtx.height/2);
//gameCtx.rotate(-player.angle+halfPi);
//gameCtx.translate(-world.worldCvs.width/2,-world.worldCvs.height/2);
gameCtx.drawImage(world.worldCvs,0,0);
//gameCtx.restore();
}
function update(dt){
world.update();
}
function init(){
//joystick setup
leftManager = nipplejs.create({
zone:document.getElementById("leftJoystick"),
color:"black",
size:75,
threshold:1.0,
position:{
top:"50%",
left:"50%"
},
mode:"static",
restOpacity:0.75,
});
rightManager = nipplejs.create({
zone:document.getElementById("rightJoystick"),
color:"black",
size:75,
threshold:1.0,
position:{
top:"50%",
right:"50%"
},
mode:"static",
restOpacity:0.75,
});
//joystick event setup
leftManager.get().on('move end', function(evt,data){
//console.log(evt);
//console.log(data);
});
rightManager.get().on('move end', function(evt,data){
//console.log(evt);
//console.log(data);
});
world.init();
main();
}
init();
`
I'm using libraries SAT.js and nipplejs.js currently.
Typically this is done in a little different of a way than you seem to be thinking of it. Instead of thinking about the viewport existing somewhere in the world, you should think about the viewport being fixed and the world being transformed behind it; you don't copy part of the world to the viewport, you draw the world offset and rotated by a certain amount, and only draw the parts that are inside the viewport. Matrices are an easy and common way to represent this transformation. You may want to read more about them here.
In practice, this would just amount to changing your existing call to worldCtx.setTransform() at the beginning of each draw frame. That link has information about how to calculate a good transform matrix, and you can find similar resources all over the place since it's pretty standard math.
In particular, you'll want to multiply a rotation and a translation matrix. Translation matrices are only possible if you use a matrix with higher-order than your coordinate space; for 2D, a 3x3 matrix, and for 3D, a 4x4 matrix. You could instead choose to just add some offset to your coordinates as you draw them, but worldCtx.setTransform already takes a matrix with a 3rd column for putting flat offsets into.
Changing the render function to the following will solve the problem, just rushing myself and didn't think things through very well.
`
function render(dt){
gameCtx.setTransform(1,0,0,1,0,0);
gameCtx.clearRect(0,0,gameCvs.width,gameCvs.height);
world.draw();
gameCtx.translate(gameCvs.width/2,gameCvs.height/2);
gameCtx.rotate(-player.angle+Math.PI);
gameCtx.translate(-cameraPoly.pos.x,-cameraPoly.pos.y);
gameCtx.drawImage(world.worldCvs,0,0);
}`
What this is doing is resetting any transformations on the context, clearing it for a new redrawing, creating the world canvas, translating to display center, rotating by the proper amount for reference point, translating to reference center point on negative axis to move game canvas proper amount so that drawing at 0,0 is in the correct location. Thank you for the reference material!
Edit;
working codepen (need to provide video file to avoid cross-origin policy)
https://codepen.io/bw1984/pen/pezOXm
I am attempting to modify the excellent rutt etra example here https://airtightinteractive.com/demos/js/ruttetra/ to work for video (still using threejs) and am encountering strange issues with performance.
My code currently works as expected, and actually runs quite smoothly on chrome on my macbook pro, but seems to cause some sort of slow memory leak which i assume is to do with all the heavy lifting which is having to be done by getImageData. Strangely enough its only noticeable once i attempt to refresh the tab, so looks like it may be related to the garbage collection in chrome maybe? anyway to shunt the grunt work onto the GPU instead of killing the CPU?
I just wondered if i am missing anything obvious in terms of code optimisation or if the performance issues i am facing are to be expected given the nature of what i am trying to do.
I am only interested in WebGL / chrome functionality so dont really need to worry about browser compatibility of any kind.
<script>
var container, camera, scene, renderer, controls;
// PI
var PI = Math.PI;
var TWO_PI = PI*2;
// size
SCREEN_WIDTH = window.innerWidth;
SCREEN_HEIGHT = window.innerHeight;
SCREEN_PIXEL_RATIO = window.devicePixelRatio;
// camera
var VIEW_ANGLE = 45;
var ASPECT = SCREEN_WIDTH / SCREEN_HEIGHT;
var NEAR = 0.1;
var FAR = 20000000;
// video raster
var video;
var videoImage;
var videoImageContext;
var _imageHeight;
var _imageWidth;
// lines
var _lineGroup;
// gui
var _guiOptions = {
stageSize: 1,
scale: 1.0,
scanStep: 5,
lineThickness: 10.0,
opacity: 1.0,
depth: 50,
autoRotate: false
};
// triggered from audio.php getMediaStream
function runme()
{
console.log('runme running');
init();
animate();
}
runme();
function init()
{
container = document.createElement('div');
document.body.appendChild(container);
//----------
// scene
//----------
scene = new THREE.Scene();
//----------
// camera
//----------
camera = new THREE.PerspectiveCamera(VIEW_ANGLE, ASPECT, NEAR, FAR);
//camera.position.set(0,0,450);
camera.position.set(0,150,300);
//----------
// objects
//----------
// create the video element
video = document.createElement('video');
// video.id = 'video';
// video.type = ' video/ogg; codecs="theora, vorbis" ';
video.src = 'data/sintel.ogv';
//video.src = 'data/az.mp4';
video.load(); // must call after setting/changing source
video.play();
videoImage = document.createElement('canvas');
//videoImage.width = 480;
//videoImage.height = 204;
videoImageContext = videoImage.getContext('2d');
_imageWidth = videoImage.width;
_imageHeight = videoImage.height;
//videoImageContext.fillStyle = '#ffffff';
//videoImageContext.fillRect(0, 0, videoImage.width, videoImage.height);
//----------
// controls
//----------
controls = new THREE.OrbitControls(camera);
//----------
// events
//----------
window.addEventListener('resize', onWindowResize, false);
//----------
// render
//----------
var args = {
//antialias: true // too slow
}
renderer = new THREE.WebGLRenderer(args);
renderer.setClearColor(0x000000, 1);
renderer.setPixelRatio(SCREEN_PIXEL_RATIO); //Set pixel aspect ratio
renderer.setSize(SCREEN_WIDTH, SCREEN_HEIGHT);
// attach to dom
container.appendChild(renderer.domElement);
//render();
}
function render()
{
if(video.readyState === video.HAVE_ENOUGH_DATA && !video.paused && !video.ended) // and video.currentTime > 0
{
//_imageWidth = videoImage.width;
//_imageHeight = videoImage.height;
videoImageContext.drawImage(video,0,0,_imageWidth,_imageHeight);
// Grab the pixel data from the backing canvas
var _data = videoImageContext.getImageData(0,0,videoImage.width,videoImage.height).data;
//log(data);
//_pixels = data;
var x = 0, y = 0;
if(_lineGroup)
{
scene.remove(_lineGroup);
//_lineGroup = null;
}
_lineGroup = new THREE.Object3D();
var _material = new THREE.LineBasicMaterial({
color: 0xffffff,
linewidth: _guiOptions.lineThickness
});
// loop through the image pixels
for(y = 0; y < _imageHeight; y+= _guiOptions.scanStep)
{
var _geometry = new THREE.Geometry();
for(x=0; x<_imageWidth; x+=_guiOptions.scanStep)
{
var color = new THREE.Color(getColor(x, y, _data));
var brightness = getBrightness(color);
var posn = new THREE.Vector3(x -_imageWidth/2,y - _imageHeight/2, -brightness * _guiOptions.depth + _guiOptions.depth/2);
//_geometry.vertices.push(new THREE.Vertex(posn));
_geometry.vertices.push(posn);
_geometry.colors.push(color);
_color = null;
_brightness = null;
_posn = null;
}
// add a line
var _line = new THREE.Line(_geometry, _material);
//log(line);
_lineGroup.add(_line);
// gc
_geometry = null;
}
scene.add(_lineGroup);
_data = null;
_line = null;
}
renderer.render(scene,camera);
}
function animate(){
requestAnimationFrame(animate);
stats.update();
render();
}
function onWindowResize(){
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
renderer.setSize(window.innerWidth, window.innerHeight);
render();
}
// Returns a hexadecimal color for a given pixel in the pixel array.
function getColor(x, y, _pixels)
{
var base = (Math.floor(y) * _imageWidth + Math.floor(x)) * 4;
var c = {
r: _pixels[base + 0],
g: _pixels[base + 1],
b: _pixels[base + 2],
a: _pixels[base + 3]
};
return (c.r << 16) + (c.g << 8) + c.b;
}
// return pixel brightness between 0 and 1 based on human perceptual bias
function getBrightness(c)
{
return ( 0.34 * c.r + 0.5 * c.g + 0.16 * c.b );
}
</script>
any help anyone could provide would be much appreciated, even if its just pointing me in the right direction as i am only just beginning to experiment with this stuff and have almost given myself an aneurysm trying to wrap my tiny mind around it.
The slow memory leak is most likely due to:
// add a line
var _line = new THREE.Line(_geometry, _material);
//log(line);
_lineGroup.add(_line);
THREE.Line is an object, containing other objects and lots of data. Every time you instantiate it, it creates .matrix, .matrixWorld, .modelViewMatrix, .normalMatrix which are all arrays with a bunch of numbers. .position,.quaternion, .scale, .rotation and probably .up are vectors,quats etc. and are slightly smaller but also arrays with special constructors.
Allocating all this every 16 miliseconds only to be released the next frame is probably the cause of your "leak".
You should create a pool of THREE.Line objects, and draw that every frame instead. The number of drawn objects you can control with .visible and mutate their transformation properties.
#pailhead I took your advice about pre-rendering the lines and lineGroup in advance and then updating the vertices on each animation frame instead and now its purring like a kitten. Also needed to insert the following line to make sure updated coords are picked up;
e.geometry.verticesNeedUpdate = true;
I cant figure out how to get a hosted video to work on codepen (cross-origin policy violation issues) but i have put a version up anyway to show the working code.
https://codepen.io/bw1984/pen/pezOXm
I will try to get a self-hosted (working) version up as soon as i can
I've been trying in vain to get colour working, but that will have to be an exercise for another day.
I'm an animator trying to branch into coding and I'm a bit stuck with fundamentals.
This is a simple character walk cycle, and I'm trying to draw the legs with code [arcTo] between the body [ManBody] and the feet [foot01].
The lines draw on and the body moves - but the lines are redrawn on EVERY frame - How/Where do I stage.update(); so that it's just a single line that draws on to the stage, and then moves between the moving parts?
//mouse cursor
stage.canvas.style.cursor = "none";
this.ManBody.mouseEnabled = false;
this.addEventListener("tick", fl_CustomMouseCursor.bind(this));
function fl_CustomMouseCursor() {
this.ManBody.x = (stage.mouseX+350) * 0.5 ;
this.ManBody.y = (stage.mouseY+200) * 0.5;
}
//line
createjs.Ticker.addEventListener("tick",fl_DrawLineCont.bind(this));
createjs.Ticker.setFPS(10);
function fl_DrawLineCont(event) {
var stroke_color = "#ff0000";
var shape = new createjs.Shape(new createjs.Graphics().beginStroke(stroke_color)
.moveTo(this.ManBody.x, this.ManBody.y)
.arcTo(this.foot01.x, this.foot01.y, this.ManBody.x, this.ManBody.y, 50).endStroke());
this.addChild(shape);
stage.update(event);
}
You creating shape every frame, you should create it outside of this and redraw it graphics like this:
var stroke_color = "#ff0000";
var graphics = new createjs.Graphics()
var shape = new createjs.Shape(graphics);
this.addChild(shape);
function fl_DrawLineCont(event)
{
graphics.clear();
graphics.beginStroke(stroke_color);
graphics.moveTo(this.ManBody.x, this.ManBody.y).arcTo(this.foot01.x, this.foot01.y, this.ManBody.x, this.ManBody.y, 50).endStroke();
stage.update(event);
}
I have a small Box2D thing (using box2dweb.js), but despite setting gravity to (0,0), and no forces/impulse being imparted on any objects, the only dynamic shape I have in the scene moves when I start the draw loop. I have no idea why O_O
Would anyone know why http://pomax.nihongoresources.com/downloads/temp/box2d/physics.html has the "ball" moving after hitting start?
The relevant bits of code are:
// shortcut aliasses
var d = Box2D.Dynamics,
v = Box2D.Common.Math,
s = Box2D.Collision.Shapes;
var ball,
gravity = new v.b2Vec2(0,0);
world = new d.b2World(gravity, true);
// setup the world box
var setupWorldBox = function(worldbox) {
var fixDef = new d.b2FixtureDef;
fixDef.density = 0;
fixDef.friction = 0;
fixDef.restitution = 0;
var bodyDef = new d.b2BodyDef;
bodyDef.type = d.b2Body.b2_staticBody;
bodyDef.position.x = worldbox.width/2;
bodyDef.position.y = worldbox.height/2;
fixDef.shape = new s.b2PolygonShape;
fixDef.shape.SetAsBox(worldbox.width/2, worldbox.height/2);
world.CreateBody(bodyDef).CreateFixture(fixDef);
}
// draw loop
var drawFrame = function() {
world.Step(1/60,10,10);
world.ClearForces();
ball.update(); // only updates the ball's DOM element position
requestAnimFrame(drawFrame);
};
// start the game
function start() {
var worldParent = document.querySelector("#world");
setupWorldBox(worldParent.getBoundingClientRect());
ball = new Ball(worldParent, document.querySelector(".ball"), d,v,s, world);
drawFrame();
}
For the main body, and the following code for defining the "ball":
var Ball = function(gamediv, element, d,v,s, world) {
var pbbox = gamediv.getBoundingClientRect();
var bbox = element.getBoundingClientRect();
this.el = element;
this.width = bbox.width;
this.height = bbox.height;
var bodyDef = new d.b2BodyDef;
bodyDef.type = d.b2Body.b2_dynamicBody;
var fixDef = new d.b2FixtureDef;
fixDef.shape = new s.b2PolygonShape;
fixDef.shape.SetAsBox(bbox.width/2, bbox.height/2);
bodyDef.position.x = bbox.left - pbbox.left;
bodyDef.position.y = bbox.top - pbbox.top;
this.b2 = world.CreateBody(bodyDef);
this.b2.CreateFixture(fixDef);
};
Ball.prototype = {
el: null,
b2: null,
width: 0, height: 0,
// Box2D position for the ball
center: function() { return this.b2.GetWorldCenter(); },
// update the DOM element based on Box2D position
update: function() {
var c = this.center();
this.el.style.left = c.x + "px";
this.el.style.top = c.y + "px";
}
};
Ball.prototype.constructor = Ball;
Neither of these bits of code introduces forces, as far as I can tell, so if anyone knows why the coordinates for the ball change anyway, please let me know, so I can turn this into something useful instead of something confusing =)
It turns out my code was creating a solid object as game world, which meant Box2D was trying to perform collision resolution because the "ball" was located inside another solid object.
The solution (based on http://box2d-js.sourceforge.net but with box2dweb API calls) was this:
// setup the world box
var setupWorldBox = function(worldbox) {
var worldAABB = new Box2D.Collision.b2AABB;
worldAABB.lowerBound.Set(0,0);
worldAABB.upperBound.Set(worldbox.width, worldbox.height);
var gravity = new b2Vec2(0, 0);
var doSleep = true;
var world = new b2World(worldAABB, gravity, doSleep);
[....]
}