I am trying to make my variable random once per time drawn
It's not clear why this warrants a question on StackOverflow, simply assign the variable a random value in the your draw() function. One way to do this is using the random().
let x;
function setup() {
createCanvas(windowWidth, windowHeight);
// slow down the frame rate so the circle doesn't jump around so quickly.
frameRate(2);
}
function draw() {
background(220);
x = random(0, width);
circle(x, height / 2, 40);
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.0/p5.js"></script>
Related
So I want to have a delay in my Draw function so that when I want to do
Xoffset = Xoffset + 1.5
I do not go from 0 to 30 in a secnd, but I want there to be some delay in the code so that I can easily manage it. I usually use scratch and if you are unfimiliar to that the command for a code delay is
Wait(Insert amount of seconds you want to delay here)
So when you start a part of the code, and the Wait is set to 2, the input will go off, wait 2 seconds, and then move on the the line of code below. I am trying to replicate that but in p5.js.
To detail my comment above, you could do something like this:
var xOffset = 0;
// time delay vars
// current time "snapshot" (imagine pressing the lap time button)
var time;
// the interval to wait between time "snapshots": 2s (2000 milliseconds) in this case
var wait = 2000;
function setup() {
createCanvas(300, 300);
//store the current time
time = millis();
}
function draw() {
background(220);
//check if the difference between now and the previously stored time
// is greater than the wait interval
if(millis() - time >= wait){
console.log(wait, "ms passed");
//if it is, do something
xOffset = xOffset + 1.5;
//also update the stored time
time = millis();
}
circle(xOffset, 150, 60);
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.0/p5.min.js"></script>
I'm not sure what the main purpose of the delay is:
is it to slow things down for debugging purposes
is to go into a series a states (e.g. ball moves up for 2s, then right
2s, etc.),
is to animate/smoothly interpolate between two positions within a given
time ?
Maybe something else completely ?
If you simply want to slow things down, perhaps it might be simpler to adjust the frameRate():
var xOffset = 0;
function setup() {
createCanvas(300, 300);
// update 1 frame every two seconds => 0.5 fps
frameRate(0.5);
}
function draw() {
background(220);
xOffset = xOffset + 1.5;
circle(xOffset, 150, 60);
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.0/p5.min.js"></script>
Processing still has a delay() function, but p5.js doesn't.
Personally I'm not a fan of blocking behaviour like this and prefer the millis() options even though it's more verbose. That being said, if the program/demo you write is super simple delay() might just be enough.
Even if delay() is missing you could use js setTimeout() with a Promise, but that's getting into more advanced JS as Paul already mentioned:
var xOffset = 0;
function setup() {
createCanvas(300, 300);
// prevent p5's default draw() updates
noLoop();
}
function draw() {
background(220);
xOffset = xOffset + 1.5;
circle(xOffset, 150, 60);
// wait 2s then call draw() manually
delay(2000).then(draw);
}
function delay(ms) {
return new Promise(resolve => setTimeout(resolve, ms));
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.0/p5.min.js"></script>
Now, if you want to create a smooth animation from a start x offset to an end offset in a set amount of seconds you'd need a different approach.
You can find a p5.js example at the of this answer:
var startTime;
var duration = 2000;
var startValue = 0;
var endValue = 300;
var currentValue = startValue;
function setup(){
createCanvas(300, 300);
textAlign(RIGHT);
startTime = millis();
}
function draw(){
background(255);
moveCircle();
drawCircle();
}
function drawCircle() {
circle(currentValue, 150, 60);
}
function moveCircle(){
var progress = (float)(millis()-startTime)/duration;//millis()-startTime = difference in time from start until now
if(progress < 1.0) currentValue = startValue + (endValue * progress);//the current value is the final value scaled/multiplied by the ratio between the current duration of the update and the total duration
}
function mousePressed(){//reset value and time
currentValue = startValue;
startTime = millis();
}
function keyPressed(){//update duration
if(key == '-') if(duration > 0) duration -= 100;
if(key == '=' || key == '+') duration += 100;
console.log("duration: " + duration);
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.0/p5.min.js"></script>
And if you're comfortable using external libraries you could simply use a tweening library such as gsap:
var x = 0;
function setup(){
createCanvas(300, 300);
// animate "this" global object's x property to 300 in 2 seconds
gsap.to(this, {x: 300, duration: 2});
}
function draw(){
background(255);
circle(x, 150, 60);
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.0/p5.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/gsap/3.8.0/gsap.min.js"></script>
Notice the animation has a bit of easing (default ease out) which could be nice.
In JavaScript, unlike Scratch, there is not a good way to delay synchronous* code. The reason for this is that all the functionality of a webpage is run using a single thread. Which means that while there can be multiple sequences of instructions performing different pieces of functionality, only one of those sequences can execute at a time. Therefore if you did something to delay the execution of JavaScript within the draw() function, it would block all other functionality, making the browser tab unresponsive (and potentially causing the browser to halt your JavaScript altogether).
Instead of pausing a series of JavaScript statements like one would do in Scratch, it is necessary to either use the amount of time that has elapsed as part of a condition that determines whether some code should run (which is what the example George shared in the comments does), or to use the built in setTimeout() function to schedule some code to run some number of milliseconds in the future (but you would not want to call setTimeout() from draw() because it would repeatedly schedule the code every frame).
* note: there are also ways to create delays using asynchronous javascript code, but this is a more advanced topic
It's like the blur is in never ending loop.
This is what I've wrote so far, it's currently always blurring it up again and again, and I can't make it un-blur.
void draw() {
filter(BLUR, blurRate/60);
nextY = mouseY-blurRate;
blurRate= nextY-mouseY;
}
It will help to split the problem into smaller subproblems.
(Kevin Workman's article is a great start)
The code you shared looks like you're trying to do two things at once:
map the mouse Y position to a blur value
apply the blur value to the blur filter
Let's start with mapping the value.
If you know what the minimum / maximum blur value you need you can make your life easier using Processing's map() function. It takes a value(mouseY in your case) and maps it from one range (mouseY's min/max range: 0 to height) to another range (blur's min/max value, let's say 0 to 6)
The mapping range above (from 0, height to 0, 6) is trivial because can simply divide height / 6 and get the mapped value, but map() is pretty useful and worth getting the hang of.
Here's a minimal mapping example:
void setup(){
}
void draw(){
float blurValue = map(mouseY, 0, height, 0, 6);
background(0);
text("blurValue: " + blurValue, 5, height / 2);
}
The second part is applying the blur filter.
The catch here is avoiding this situation:
currently always blurring it up again and again,
This happens because you apply the blur filter in draw() multiple times per second to the content, so each pass blurs further.
It sounds like what you want is to apply the blur filter to the initial state of your image or graphics. The code you posted doesn't show what is it that you're trying to blur.
If using graphics rendered in processing, one option is to simply clear everything (using background()) and redrawing the graphics before applying the filter. With the filter applied in draw and nothing cleared/redrawn the effect is reapplied to the same (pre blurred) content continously.
Let's take this basic example:
void setup(){
}
void draw(){
line(mouseX, mouseY, pmouseX, pmouseY);
}
Notice that even draw we render a single tiny line, because the graphics aren't cleared (using background()) each tiny line accumulates to form a larger path.
Intuitively, adding blur will accumulate the effect:
void setup(){
}
void draw(){
line(mouseX, mouseY, pmouseX, pmouseY);
filter(BLUR, 0.6);
}
Another option, if you'd rather be more efficient and re-render the same graphics in draw(), you can get an image copy of what's been rendered so far which you could render continuously.
Let's say you're drawing something in setup().
You can easily call get()(with no arguments) to get a "snapshot" of what's been drawn so far a PImage.
Once you have that you can simply render it again and again in draw() as it was drawn in setup() using image().
Once image() is called you can then call filter() with be applied to the global Processing graphics, meaning only what's rendered (while the snapshot PImage will remain intact).
Here's an example illustrating the above:
PImage snapshot;
void setup(){
// draw something
background(0);
noFill();
strokeWeight(3);
for(int i = 0 ; i < 100; i++){
stroke(random(32, 128));
float size = random(3, 27);
ellipse(random(width), random(height), size, size);
}
// take a snapshot of the current graphics
snapshot = get();
}
void draw(){
float blurValue = map(mouseY, 0, height, 0, 6);
// render the image snapshot
image(snapshot, 0, 0);
// blur it
filter(BLUR, blurValue);
// display blur value (should be unblurred)
text("blurValue: " + blurValue, 5, height / 2);
}
Your question doesn't specify, but if you are using PImage, then you need to apply blur to a copy of the image to avoid re-applying blur to an already blurred image. Here's a PImage tweaked version of the above:
PImage snapshot;
void setup(){
// draw something
background(0);
noFill();
strokeWeight(3);
for(int i = 0 ; i < 100; i++){
stroke(random(32, 128));
float size = random(3, 27);
ellipse(random(width), random(height), size, size);
}
// take a snapshot of the current graphics
snapshot = get();
}
void draw(){
float blurValue = map(mouseY, 0, height, 0, 6);
// clone the original image via get()
PImage blurredImage = snapshot.get();
// blur the cloned image
blurredImage.filter(BLUR, blurValue);
// display the blurred image
image(blurredImage, 0, 0);
// display blur value (should be unblurred)
text("blurValue: " + blurValue, 5, height / 2);
}
I have a simple ellipse, moving across the screen, is there any simple code I could implement to have this ellipse draw a trail behind it that has its alpha fade over time to a certain extent? I still want the trail visible in the end but less bright than the casting ellipse.
You could also do something like this:
let positions = [];
function draw(){
positions.push(mouseX);
positions.push(mouseY);
for(let i in positions){
let x = positions[i];
let y = positions[i + 1];
fill(255, 255 - i * 10); noStroke();
ellipse(mouseX, mouseY, x, y)
}
if(positions.length > 20){
positions.shift();
positions.shift();
}
}
Assuming the ellipse is the only thing being drawn then there is a simple solution which is to, instead of drawing a fully opaque background on each frame, draw a semi-transparent background:
function setup() {
createCanvas(windowWidth, windowHeight);
}
function draw() {
background(0, 35);
ellipse(mouseX, mouseY, 20, 20);
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.0/p5.js"></script>
However, there are some caveats, namely that for certain colors/transparency levels you will be left with permanent "ghost" of the trails due to some weird alpha blending math anomalies.
This is my first week playing with P5js and Processing so be gentle.
I've got the following P5js code where I'm looking at touch values. By pressing multi-points on a touch screen brings up more circles anchored to a central position.
What I'd like to know is how do I call the x value for object 1 that's printed in the console? or y value for object 0? how would i state them in the code?
What I'd like to do is use these values to change the dimensions of a shape in the middle of the screen, like something in object 0 driving the height of the shape or object 1 on the the x or y values driving strokeWeight or colour . However I'm in my first week and completely lost to how to use these values in the code.
function setup() {
createCanvas(windowWidth, windowHeight);
background(200);
}
function draw() {
background(255);
fill(255, 0, 0);
strokeWeight(0)
for (var i = 0; i < touches.length; i++) {
fill(255);
strokeWeight(3)
ellipse(touches[i].x, touches[i].y, 50, 50);
line(touches[i].x, touches[i].y, windowWidth / 2, windowHeight / 2);
fill(255);
ellipse(windowWidth / 2, windowHeight / 2, 10, 10);
print(touches);
}
}
// do this prevent default touch interaction
function mousePressed() {
return false;
}
document.addEventListener('gesturestart', function(e) {
e.preventDefault();
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.5.2/p5.min.js"></script>
or Sketch file is here
any help would be muchly muchly appreciated, i'm a newb trying to find my way
There is only one mistake in it which I found till now, the color of the background and the fill colors are the same! you may change them to actually see the shapes, lines etc.
Hi How do I make bullets to collide with the objects in Processing ?
Bullets are fired and being translated and rotated
but whenever i try to use function dist() it always gives me 0 as the position of the vector
How do i get the correct vector position if i want the bullet to collide with objects using distance and make the the other object disappear ?
Here's the code
void move(){
passed = passed + time;
if (passed > bulletLife) {
alive = false;
}
forward.x = sin(theta);
forward.y = -cos(theta);
float speed = 15.0f;
velocity = PVector.mult(forward, speed);
side.add(forward);
void display(){
pushMatrix();
translate(side.x, side.y);
rotate(theta);
stroke(255);
ellipse(side.x, side.y, 30, 30);
popMatrix();
Thanks
You're getting 0 from dist() because translate() moves the coordinate system! I think, more than your question, you need to reconsider your code overall. You translate to side.x, side.y (which will then be 0,0 until you call popMatrix()) but then you draw the ellipse at side.x, side.y which is offset from its actual position.
In other words: if the position is 100,200, you're actually drawing the object at 200,400!
If you skip the translate() part, you can use this to draw your object:
void display() {
stroke(255);
ellipse(side.x, side.y, 30,30);
}
And this to check collision:
if (dist(side.x, side.y, bullet.x, bullet.y) == 0) {
collision = true;
}
else {
collision = false;
}
You can also see my collision-detection functions for Processing, which have lots of examples that might help.