copy function does not recognize image on another canvas in p5js - javascript

I'm trying to make 'slitscan' effects.
I set 2 canvases. One on the right is for source image, and another is for scan effect.
When i tried it with text function it works perfectly, however with an image, the copy function gives me an error message.
This is the p5 code I wrote
let a1, a2;
let cv1, cv2;
let dy = 0;
let s1 = function(p) {
p.setup = () => {
cv1 = p.createCanvas(300, 300);
p.background(150);
cv1.position(0, 0);
}
p.draw = () => {
p.copy(cv2, 0, dy, 400, 1, 0, dy, 400, 1);
if (dy > cv2.height) {
dy = 0;
} else {
dy += 1;
}
}
}
a1 = new p5(s1);
let s2 = function(p) {
let img;
p.preload = () => {
img = p.loadImage('https://pbs.twimg.com/profile_images/635910989498724356/uY4bc8q2.jpg');
}
p.setup = () => {
cv2 = p.createCanvas(300, 300);
cv2.position(300, 0);
}
p.draw = () => {
p.background(30);
p.imageMode(p.CENTER);
p.image(img, p.mouseX, p.mouseY);
}
}
a2 = new p5(s2);
In addition, if you have a better idea to make multi-canvas or any suggestion about my code, please leave a comment.
Thanks,

In your s1 sketch, you try to do stuff with the canvas cv2. Yet this canvas is only created later in your sketch.
To fix it, just change the order of your two sketches, i.e., call a1 = new p5(s1); after a2 = new p5(s2); (it doesn't matter when you define s1 and s2, only when you instantiate them).
See, for example, this p5 editor sketch.

Related

Images onload in one function

I'm trying to learn JavaScript, making my first game. How I can make all images onload in one function and later draw it in the canvas making my code shorter?
How can I put a lot of images in an array and later us it in a function.
This is my third day of learning JavaScript.
Thanks in advance.
var cvs = document.getElementById('canvas');
var ctx = cvs.getContext('2d');
//load images
var bird = new Image();
var bg = new Image();
var fg = new Image();
var pipeNorth = new Image();
var pipeSouth = new Image();
//images directions
bg.src = "assets/bg.png";
bird.src = "assets/bird.png";
fg.src = "assets/fg.png";
pipeNorth.src = "assets/pipeNorth.png";
pipeSouth.src = "assets/pipeSouth.png";
var heightnum = 80;
var myHeight = pipeSouth.height+heightnum;
var bX = 10;
var bY = 150;
var gravity = 0.5;
// Key Control :D
document.addEventListener("keydown",moveUP)
function moveUP(){
bY -= 20;
}
//pipe coordinates
var pipe = [];
pipe[0] = {
x : cvs.width,
y : 0
}
//draw images
//Background img
bg.onload = function back(){
ctx.drawImage(bg,0,0);
}
//pipe north
pipeNorth.onload = function tubo(){
for(var i = 0; i < pipe.length; i++){
ctx.drawImage(pipeNorth,pipe[i].x,pipe[i].y);
pipe[i].x--;
}
}
pipeSouth.onload = function tuba(){
ctx.drawImage(pipeSouth,pipe[i].x,pipe[i].y+myHeight);
}
bird.onload = function pajaro(){
ctx.drawImage(bird,bX,bY);
bY += gravity;
requestAnimationFrame(pajaro);
}
fg.onload = function flor(){
ctx.drawImage(fg,0,cvs.height - fg.height);
}
moveUP();
back();
tuba();
pajaro();
flor();
This can be done with Promise.all. We'll make a new promise for each image we want to load, resolving when onload is called. Once Promise.all resolves, we can call our initialize function and continue on with the rest of our logic. This avoids race conditions where the main game loop's requestAnimationFrame is called from bird.onload, but it's possible that pipe entities and so forth haven't loaded yet.
Here's a minimal, complete example:
const initialize = images => {
// images are loaded here and we can go about our business
const canvas = document.createElement("canvas");
document.body.appendChild(canvas);
canvas.width = 400;
canvas.height = 200;
const ctx = canvas.getContext("2d");
Object.values(images).forEach((e, i) =>
ctx.drawImage(e, i * 100, 0)
);
};
const imageUrls = [
"http://placekitten.com/90/100",
"http://placekitten.com/90/130",
"http://placekitten.com/90/160",
"http://placekitten.com/90/190",
];
Promise.all(imageUrls.map(e =>
new Promise((resolve, reject) => {
const img = new Image();
img.onload = () => resolve(img);
img.onerror = reject;
img.src = e;
})
)).then(initialize);
Notice that I used an array in the above example to store the images. The problem this solves is that the
var foo = ...
var bar = ...
var baz = ...
var qux = ...
foo.src = ...
bar.src = ...
baz.src = ...
qux.src = ...
foo.onload = ...
bar.onload = ...
baz.onload = ...
qux.onload = ...
pattern is extremely difficult to manage and scale. If you decide to add another thing into the game, then the code needs to be re-written to account for it and game logic becomes very wet. Bugs become difficult to spot and eliminate. Also, if we want a specific image, we'd prefer to access it like images.bird rather than images[1], preserving the semantics of the individual variables, but giving us the power to loop through the object and call each entity's render function, for example.
All of this motivates an object to aggregate game entities. Some information we'd like to have per entity might include, for example, the entity's current position, dead/alive status, functions for moving and rendering it, etc.
It's also a nice idea to have some kind of separate raw data object that contains all of the initial game state (this would typically be an external JSON file).
Clearly, this can turn into a significant refactor, but it's a necessary step when the game grows beyond small (and we can incrementally adopt these design ideas). It's generally a good idea to bite the bullet up front.
Here's a proof-of-concept illustrating some of the the musings above. Hopefully this offers some ideas for how you might manage game state and logic.
const entityData = [
{
name: "foo",
path: "http://placekitten.com/80/80",
x: 0,
y: 0
},
{
name: "baz",
path: "http://placekitten.com/80/150",
x: 0,
y: 90
},
{
name: "quux",
path: "http://placekitten.com/100/130",
x: 90,
y: 110
},
{
name: "corge",
path: "http://placekitten.com/200/240",
x: 200,
y: 0
},
{
name: "bar",
path: "http://placekitten.com/100/100",
x: 90,
y: 0
}
/* you can add more properties and functions
(movement, etc) to each entity
... try adding more entities ...
*/
];
const entities = entityData.reduce((a, e) => {
a[e.name] = {...e, image: new Image(), path: e.path};
return a;
}, {});
const initialize = () => {
const canvas = document.createElement("canvas");
document.body.appendChild(canvas);
canvas.width = innerWidth;
canvas.height = innerHeight;
const ctx = canvas.getContext("2d");
for (const key of Object.keys(entities)) {
entities[key].alpha = Math.random();
}
(function render () {
ctx.clearRect(0, 0, canvas.width, canvas.height);
Object.values(entities).forEach(e => {
ctx.globalAlpha = Math.abs(Math.sin(e.alpha += 0.005));
ctx.drawImage(e.image, e.x, e.y);
ctx.globalAlpha = 1;
});
requestAnimationFrame(render);
})();
};
Promise.all(Object.values(entities).map(e =>
new Promise((resolve, reject) => {
e.image.onload = () => resolve(e.image);
e.image.onerror = () =>
reject(`${e.path} failed to load`)
;
e.image.src = e.path;
})
))
.then(initialize)
.catch(err => console.error(err))
;

How to draw clickable line in PIXI.js using PIXI.Graphics?

I have got the following code:
const linksGraphics = new PIXI.Graphics();
const update = () => {
linksGraphics.clear();
linksGraphics.alpha = 1;
if (forceLinkActive) {
data.links.forEach(link => {
let { source, target } = link;
linksGraphics.lineStyle(2, 0x000000);
linksGraphics.moveTo(source.x, source.y);
linksGraphics.lineTo(target.x, target.y);
});
linksGraphics.endFill();
} }
app.ticker.add( () => update() );
Where data.links is an array of edge data {source: number, target: number}. If I understand right, all lines are part of the PIXI.Graphics object. But what I need:
every line should have own opacity
every line should have an event for mouse over
Any ideas how modify my code?
Thanks.
It's been a while but can make a suggestion. Lines do not react to mouse/pointer over events in pixijs.
Instead you may want to accompany a transformed rectangle with alpha value 0 and listen mouse/pointer with this rectangle.
For example lets, change the alpha value of the line when mouse/pointer hovers the accompanying rectangle.
const app = new PIXI.Application({
width: window.innerWidth,
height: window.innerHeight,
backgroundColor: 0x283230
});
document.body.appendChild(app.view);
// 1. PRELIMINARY COMPUTATIONS
// Coordinates of the end points of a line
let x0 = 100;
let y0 = 100;
let x1 = 200;
let y1 = 200;
// Find midpoint for translation
let xmid = 0.5*(x0+x1);
let ymid = 0.5*(y0+y1);
// Length of the line
let length = Math.hypot(x0-x1, y0-y1);
// Alignment angle of the line, i.e. angle with the x axis
let angle = Math.atan((y1-y0)/(x1-x0));
// 2. LINE
line = new PIXI.Graphics();
// Arbitrary line style, say we have a non-white background
line.lineStyle(8,0xffffff,1);
line.moveTo(x0,y0);
line.lineTo(x1,y1);
// 3. ACCOMPANYING RECTANGLE
line.rectangle = new PIXI.Graphics();
line.rectangle.beginFill(0xffffff);
// Since we are going to translate, think of 0,0 is the center point on the rectangle
// Width of the rectangle is selected arbitrarily as 30
const width = 30;
line.rectangle.drawRect(-length/2,-width/2,length,width);
line.rectangle.endFill();
line.rectangle.alpha = 0;
line.rectangle.interactive = true;
line.rectangle.on("pointerover", reactOver);
line.rectangle.on("pointerout", reactOut);
// Apply transformation
line.rectangle.setTransform(xmid, ymid,1,1,angle);
app.stage.addChild(line);
// Add rectangle to the stage too.
app.stage.addChild(line.rectangle);
// Let's change alpha value of the line when user hovers.
function reactOver(){
line.alpha = 0.5;
}
function reactOut(){
line.alpha = 1;
}
To the PEN, Hover a line in pixijs
We can expand this logic to a rectangle for instance. But this time you need two accompanying rectangles (with alpha=0) where one of them is wider and the other is narrower than the unfilled rectangle. For example,
const app = new PIXI.Application({
width: window.innerWidth,
height: window.innerHeight,
backgroundColor: 0x283230
});
document.body.appendChild(app.view);
const x = 100;
const y = 100;
const width = 150;
const height = 100;
const hoverWidth = 20;
const rect = new PIXI.Graphics();
rect.lineStyle(4, 0xffffff,1);
rect.drawRect(x,y,width,height);
rect.outer = new PIXI.Graphics();
rect.inner = new PIXI.Graphics();
// Fill outer
rect.outer.alpha = 0;
rect.outer.beginFill(0xffffff);
rect.outer.drawRect(x-hoverWidth/2, y-hoverWidth/2, width+hoverWidth, height+hoverWidth);
rect.outer.endFill();
// Fill inner
rect.inner.alpha = 0;
rect.inner.beginFill(0xffffff);
rect.inner.drawRect(x+hoverWidth/2, y+hoverWidth/2, width-hoverWidth, height-hoverWidth);
rect.inner.endFill();
// Add interaction and listeners
rect.outer.interactive = true;
rect.inner.interactive = true;
rect.outer.on("pointerover", pOverOuter);
rect.outer.on("pointerout", pOutOuter);
rect.inner.interaction = true;
rect.inner.on("pointerover", pOverInner);
rect.inner.on("pointerout", pOutInner);
app.stage.addChild(rect);
app.stage.addChild(rect.outer);
app.stage.addChild(rect.inner);
// Listeners
let overOuter = false;
let overInner = false;
function pOverOuter(){
overOuter = true;
changeAlpha();
// rect.alpha = 0.5;
}
function pOutOuter(){
overOuter = false;
changeAlpha();
}
function pOverInner(){
overInner = true;
changeAlpha();
// rect.alpha = 1;
}
function pOutInner(){
overInner = false;
changeAlpha();
// rect.alpha = 0.5;
}
function changeAlpha(){
rect.alpha = (overOuter && !overInner)? 0.5: 1;
}
To the PEN, Hover a rectangle in pixijs
For your first requirement, try creating separate graphics objects for drawing each line and set alpha for each line.
For your second requirement, You need to set the interactive property of graphics (linksGraphics) object to true like below,
linksGraphics.interactive = true;
and then attach a function to be executed on mouseover event like below,
var mouseOverAction = function () {
//Some code
};
linksGraphics.on('mouseover', mouseOverAction);
You can define a hitArea on a graphic. And with getBounds() you can make a line clickable. After you do that you can also assign pointerEvents to the graphic.
const linksGraphics = new PIXI.Graphics();
const update = () => {
linksGraphics.clear();
linksGraphics.alpha = 1;
if (forceLinkActive) {
data.links.forEach(link => {
let { source, target } = link;
linksGraphics.lineStyle(2, 0x000000);
linksGraphics.moveTo(source.x, source.y);
linksGraphics.lineTo(target.x, target.y);
//A line itself is not clickable
linksGraphics.hitArea = linksGraphics.getBounds();
});
linksGraphics.endFill();
}
}
app.ticker.add( () => update() );

Changing stroke colour using recursion

I am struggling with the error of which throw me once I am trying to recursively change a colour. The error is: “Uncaught TypeError Cannot read property ‘map’ of undefined (sketch: line 18)” and reference to this piece of code: this.color.levels.map(x => x * 0.9) .
I supposed that’s because of a recursive and problem with “this” context. The “right” function which I’ve created executing just one time until above error is thrown.
Any ideas how to make this work or how to recursively change the colour referencing to the same object which I’ve been created?
My code: https://editor.p5js.org/grzegorz.kuguar#gmail.com/sketches/Syc1qQmnQ
<code> class Branch {
constructor(begin, end, strokeW, color, angle) {
this.begin = begin;
this.end = end;
this.angle = angle;
this.strokeW = strokeW;
this.color = color;
}
display() {
stroke(this.color);
strokeWeight(this.strokeW);
line(this.begin.x, this.begin.y, this.end.x, this.end.y);
}
right(angle) {
let direction = p5.Vector.sub(this.end, this.begin);
direction.rotate(angle);
let nextPoint = p5.Vector.add(direction, this.end);
let right = new Branch(this.end, nextPoint, this.strokeW*0.7, this.color.levels.map(x => x * 0.9)); //this line of code throw an error once I am trying to manipulate on the array
return right;
}
}
let tree = [];
let trunk;
let something; //just for check how looks like a p5.color object
function setup() {
createCanvas(400, 400);
background(20);
something = color(100, 230, 100);
console.log(something);
let x = createVector(width/2, height);
let y = createVector(width/2, height-100);
trunk = new Branch(x,y, 7, color(255,100, 100));
tree[0] = trunk;
tree.push(trunk);
}
function draw() {
for(let i = 0; i < tree.length; i++) {
tree[i].display();
}
}
function mousePressed() {
for(let i = tree.length-1; i >= 0; i--) {
tree.push(tree[i].right(Math.PI/4, 0.66));
}
}
The problem is in your use of map. You are doing:
this.col.levels.map(x => x * 0.9)
which returns an array, not a p5.Color object.
To create the new color object, instead use:
color.apply(this, this.col.levels.map(x => x * 0.9))
You can see the full sketch here

p5js instance mode and object orientation

I have a "sketch.js" where i want to instance multiple canvases und display different objects of one class in them.
sketch.js:
var myObjects = [];
var sketch1 = function (p) {
p.setup = function () {
p.createCanvas(600, 400);
}
p.draw = function () {
p.background(51);
p.rect(p.width/2, p.height/2, 200, 200);
}
};
new p5(sketch1, "canvas_container");
var sketch2 = function (p) {
p.setup = function () {
p.createCanvas(600, 400);
myObjects.push(new myObject(p, 1, 2));
myObjects.push(new myObject(p, 3, 4));
}
p.draw = function () {
p.background();
for (var i=0; i<myObjects.length; i++) {
p.line(0, 0, myObjects[i].x, myObjects[i].y);
myObjects[i].doSomething(Math.random()*10);
}
}
};
new p5(sketch2, "canvas_container");
When do i use "this." and when "p." in this case?
Furthermore I would like to use some "other" methods from the p5 library in my sketch.js file, outside of the instaces, like:
select('..') ...
but I get the error:
select is not defined
I found myself a dirt workaround:
new p5().select('...') ...
What is the clean way to do this?
myObjects.js
function myObject(canvas, x, y) {
this.canvas = canvas;
this.x = x;
this.y = y;
this.doSomething = function(rad) {
this.canvas.ellipse(this.x, this.y, rad, rad);
}
}
Has anybody an example for handeling multiple instances of canvases?
Note that right now, you aren't ever creating a new instance of myObject. Your array is named myObjects, but you're only ever adding p (which is an instance of p5) to it. So you can't magically call your doSomething() function on the objects you've added to your myObjects array, because they aren't myObject objects. They're p5 objects.
I think what you would want to do is take the p variable passed into each of your sketches and pass that into your "class" functions. Something like this:
p.setup = function () {
p.createCanvas(600, 400);
var myObjectOne = new myObject(p, 1, 2);
var myObjectTwo = new myObject(p, 3, 4);
}
Then it should work how you're expecting it to.

Initiation of an object inside another

I have a piece of js software that is structured like so:
obj = new object[id]();
function wrapperFunction (e) {
var pos = findPos(this);
e._x = e.pageX - pos.x;
e._y = e.pageY - pos.y;
var func = obj[e.type];
if (func) {
func(e);
}
}
__
obj.line = function () {
this.started = false;
this.mousedown = function (e) {
}
this.mousemove = function (e) {
if (this.started) {
}
}
this.mouseup = function (e) {
if (this.started) {
}
}
}
The above code block is duplicated for multiple shapes so there is also a obj.square obj.circle etc...
I also have a shape object that is as follows.
function Shape (type, color, height, width, radius, x, y) {
this.type = type;
this.color = color;
this.h = height;
this.w = width;
this.r = radius;
this.points = ["x","y"];
this.points["x"] = [x];
this.points["y"] = [y];
};
I would like to initiate the shape object on a mousedown for each obj.* and populate the shape object with the propper info.
Now for the issue.
The radius is calcuated on every mousemove as well as height and width but when I add shapes = new Shape(circle, black, 10, 10, null, e._x, e._y) to the mousemove so it looks like...
this.mousemove = function (e) {
if (this.started) {
shapes = new Shape(circle, black, 10, 10, null, e._x, e._y);
}
}
The shape object does not create.
If I create the shape object inside the wrapper function instead of the mousemove then the object initiates but I cannot use radius or height/width.
How can I create an object inside another object inside a wrapper function so I can use calculated terms inside the created object? Is there an alternate route to take besides what I am doing?
Aside from wonkiness in the obj = new object[this.id](); line, I think you're just missing a this keyword:
this.mousemove = function (e) {
if (this.started) {
this.shapes = new Shape(circle, black, 10, 10, null, e._x, e._y);
}
}
Edit just noticed more wonkiness in your code (yes, that's a technical term :). I think you want to change these lines in the constructor:
this.points = ["x","y"]; // creates an array, which is indexed by numbers
this.points["x"] = [x]; // tacks on some ad-hoc properties to the array, which
this.points["y"] = [y]; // doesn't really make sense
to this:
this.points = {x: x, // I think this is what you actually mean to do.
y: y};

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