random position in a specific area(=big circle)

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sunooz

random position in a specific area(=big circle)

in General Discussion • Other • 1 year ago

I want to put several circles(pink one) at random positions in the bigger circle(sky blue one)

Circles should not be in grey area... they should be at RANDOM POSITION IN BLUE AREA.

Is there any solution? Is this possible?

I read an article about similar subject ( http://forum.processing.org/topic/random-position-in-a-specific-area) but it does not help me because I cannot use the color value of x,y position.

The background image of my sketch is kind of picture or drawing.... So the Blue circle is something virtual and invisible.

The image abobe is what I drew roughly to explain my question. You can ignore it...

In conclusion, can i assign a specific area with big circular shape for random positions of smaller circles?

Using random(a, b), random(c, d) only gives me square area... I want circle!

Replies(10)

PhiLho

Re: random position in a specific area(=big circle)

1 year ago

Two solutions:
- The color one, you can just have your "virtual" circle in a PImage and get() from there, at the same coordinates than on the sketch.
- Or by math: compute a random radius (in the bounds of the circle), a random angle from the center of the big circle, and put a circle there.

cedrickie..

Re: random position in a specific area(=big circle)

1 year ago

like this :

x = width/2+ cos( randomVal )*radius;

y = height/2+ sin( randomVal )*radius;

sunooz

Re: Re: random position in a specific area(=big circle)

1 year ago

What is randomVal? Can anybody explain the code by cedrickefer? Where should I put those codes in my sketch?

calsign

Re: random position in a specific area(=big circle)

1 year ago

Here, x and y are the coordinates of the randomly positioned circle. randomVal should be a random number between 0 and TWO_PI. Example:

float randomVal = random(0, TWO_PI);
x = width/2+ cos( randomVal )*radius;
y = height/2+ sin( randomVal )*radius;

sunooz

Re: Re: random position in a specific area(=big circle)

1 year ago

It doesn't work...... What's wrong with my code?

Circle[] circles;
int numCircles = 13; //number of circles
int maxDistance; //max distance between circles when draw lines
int minDistance;
int m;
float bgX;
float bgY;
float randomVal;
float circleX;
float circleY;
PImage bg;
PImage bgRed;
void setup() {
size(displayWidth, displayHeight); //size of window
smooth(); //draw circles with anti-aliased edge
m = millis();
bgX = (displayWidth-800)/2;
bgY = (displayHeight-800)/2;
randomVal = random(0, TWO_PI);
circleX = width/2 + cos(randomVal)*400;
circleY = height/2 + sin(randomVal)*400;
bg = loadImage("bg_trans.png");
bgRed = loadImage("bg_red.png");
// create an array and fill it with circles
circles = new Circle[numCircles]; //create an array of circles
for (int i=0; i< numCircles; i++) {
//random position in the window, random size between 5-15
circles[i] = new Circle(circleX, circleY, random(2, 10), random(150, 255));
}
}
void draw() {
// clear background
background(0, 0, 25);
tint(255, 50);
image(bg, bgX, bgY);
tint(255, 50);
image(bgRed, bgX, bgY);
// update and display the circles
for (int i=0; i< numCircles; i++) {
circles[i].update();
circles[i].display();
}
// define maximum distance
maxDistance = 300;
//minDistance = 50;
//maxDistance = mouseX; //manuplate lines by mouse cursor
// look of the lines
stroke(255, 130);
strokeWeight(0.5);
for (int i=0; i< numCircles; i++) {
// compare circle to other circles
for (int j=i+1; j< numCircles; j++) {
// draw line if distance is below 'maxDistance'
if (dist(circles[i].x, circles[i].y, circles[j].x, circles[j].y) < maxDistance){
line(circles[i].x, circles[i].y, circles[j].x, circles[j].y);
}
}
}
}

PhiLho

Re: random position in a specific area(=big circle)

1 year ago

Well, one problem is that we don't have the Circle class, so we don't know what is done there.
The other problem is that you compute the circleX and circleY values only once, applying it on each Circle instance. So it is no longer random...
Put the lines 26-28 in the loop creating the Circles, just before the constructor call.
Improvement on your code:

float randomAngle = random(0, TWO_PI);
float randomRadius = random(20, 400); // Not too close of the center, adjust at will
float circleX = width/2 + cos(randomAngle) * randomRadius;
float circleY = height/2 + sin(randomAngle) * randomRadius;

Note that these values doesn't need to be global...

[EDIT] Oops, I forgot to change randomVal to randomAngle! Fixed above to reduce confusion...

sunooz

Re: Re: random position in a specific area(=big circle)

1 year ago

Oh, here's Circle class..

class Circle {
float x, y, dia, opa;
float speed=0;
float gravity=0.1;
float fallLimit = bgY + 780; //limit y for falling stars
Circle(float x, float y, float dia, float opa) {
this.x =x;
this.y =y;
this.dia = dia;
this.opa = opa;
}
//circles move slightly in their position
void update() {
// code for movement here
// this is just some random displacement
x = x + random(-0.2, 0.2);
y = y + random(-0.2, 0.2);
int m = millis();
speed = speed + gravity;
if(y < fallLimit){
y = y + speed;
}
if (y > fallLimit) {
y = fallLimit;
}
}
void display() {
// code for drawing the circles
noStroke();
fill(255, opa);
ellipse(x, y, dia, dia);
}
}

sunooz

Re: Re: random position in a specific area(=big circle)

1 year ago

still doesn't work with this;

float randomAngle = random(0, TWO_PI);
float randomRadius = random(20, 400); // Not too close of the center, adjust at will
float circleX = width/2 + cos(randomVal) * randomRadius;
float circleY = height/2 + sin(randomVal) * randomRadius;

every circles are overlapped on one point... They are not randomly distributed in big circle. T_T..

calsign

Re: random position in a specific area(=big circle)

1 year ago

Two things:

Make sure that you use randomValue (a random number between 0, and TWO_PI) instead of randomVal (a variable declared globally with a value of 0).

Make sure that you calculate the random values for each circle; in other words, put it inside the for loop.

This should work:

for (int i=0; i< numCircles; i++) {
float randomAngle = random(0, TWO_PI);
float randomRadius = random(20, 400); // Not too close of the center, adjust at will
float circleX = width/2 + cos(randomAngle) * randomRadius;
float circleY = height/2 + sin(randomAngle) * randomRadius;
println(circleX + ", " + circleY);
//random position in the window, random size between 5-15
circles[i] = new Circle(circleX, circleY, random(2, 10), random(150, 255));
}

If you want it to look more circle-ish, add more circles.

PhiLho

Re: random position in a specific area(=big circle)

1 year ago

Yes, sorry for the confusion, I forgot to change one variable for the other.

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