Searching the closest point in a double for loop.

Programming Questions

p3tr4s

Searching the closest point in a double for loop.

in Programming Questions • 10 months ago

Hi,

I have a double "for() loop" in order to create a grid of points:
The problem I have I want to find distance between every point in a grid (between brackets I wrote float distance and if statement).

But it does not search for every point in a grid, it measures only distance between vec1 and vec2....

So the question is how to measure distance between all points in a grid, in order to draw a line if the distance is between 0 and 40? Is it possible to do that?

I want my gridpoints to have separation/flocking behavior (see the links below).
I need this because points overlap when attraction or repulsion forces are stronger than the default value.

To visualise what I want is picture link ---> SEARCHING THE CLOSEST
The picture is from Chose Sanchez tutorial ----> VIDEO

In the script there are main tab and two classes named: Electron and Vector.

for (int y = 0; y<gridDim-1; y++) {
    for (int x = 0; x<gridDim; x++) {

      Vector vec1 = field.get(x+y*gridDim);
      Vector vec2 = field.get(x+(y+1)*gridDim);
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
      float distance = dist(vec1.pos.x+(vec1.dir.x)*value/multi, vec1.pos.y+(vec1.dir.y)*value/multi, vec2.pos.x+(vec2.dir.x)*value/multi, vec2.pos.y+(vec2.dir.y)*value/multi);
           if (distance > 0 && distance< 40) {
             stroke(1);
        line(vec1.pos.x+(vec1.dir.x)*value/multi, vec1.pos.y+(vec1.dir.y)*value/multi, vec2.pos.x+(vec2.dir.x)*value/multi, vec2.pos.y+(vec2.dir.y)*value/multi);
      }
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
     ellipse(vec1.pos.x+(vec1.dir.x)*value/multi, vec1.pos.y+(vec1.dir.y)*value/multi, 20, 20);
    }
}

whole script including the part written above:

int gridDim = 15;
int numCharges = 3;
float maxStrengthPerCharge = 100/numCharges;
ArrayList <Vector> field = new ArrayList <Vector> ();
ArrayList <Electron> charges = new ArrayList<Electron>();

PVector speed = new PVector();

boolean fullGrid;
float value = 1;
int multi = 400;

void setup() {
size(600, 600);
smooth();
strokeWeight(0.5);
int w = width/gridDim;
int h = height/gridDim;
for (int y = 0; y<gridDim; y++) {
    for (int x = 0; x<gridDim; x++) {
      field.add(new Vector((x+0.5)*w, (y+0.5)*h));//ARRAY OF GRID POINTS
    }
}
resetElectrons();
}

void draw() {
background(255);
for (Electron e : charges) {
    e.display();
}
for (Vector v : field) {
    v.update();
}

for (int y = 0; y<gridDim-1; y++) {
    for (int x = 0; x<gridDim; x++) {

      Vector vec1 = field.get(x+y*gridDim);
      Vector vec2 = field.get(x+(y+1)*gridDim);
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
      float distance = dist(vec1.pos.x+(vec1.dir.x)*value/multi, vec1.pos.y+(vec1.dir.y)*value/multi, vec2.pos.x+(vec2.dir.x)*value/multi, vec2.pos.y+(vec2.dir.y)*value/multi);
           if (distance > 0 && distance< 40) {
             stroke(1);
        line(vec1.pos.x+(vec1.dir.x)*value/multi, vec1.pos.y+(vec1.dir.y)*value/multi, vec2.pos.x+(vec2.dir.x)*value/multi, vec2.pos.y+(vec2.dir.y)*value/multi);
      }
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
     ellipse(vec1.pos.x+(vec1.dir.x)*value/multi, vec1.pos.y+(vec1.dir.y)*value/multi, 20, 20);
    }
}
move();
}

void move() {
value = 1 + value*0.98;
}

void resetElectrons() {
charges.clear();
for (int i = 0; i<numCharges; i++) {
    charges.add(new Electron(400, 400, 20));
    charges.add(new Electron(200, 300, 20));
    charges.add(new Electron(500, 200, 20));
}
}
class Electron {
PVector pos;
float charge;

Electron(float x, float y, float charge) {
    pos = new PVector (x, y);
    this.charge=charge;
}
void display() {
    pushMatrix();
    translate(pos.x, pos.y);
    noStroke();
    fill(0);
    ellipse(0, 0, charge, charge);
    popMatrix();
}
}
class Vector {
PVector pos, dir;

Vector(float x, float y) {
    pos = new PVector(x, y);
    dir = new PVector();
}

void update() {
    dir.set(0, 0, 0);
    for (Electron e : charges) {
      PVector currentDir = e.pos.get();
      float magnitude = map(currentDir.dist(pos), 0, width, maxStrengthPerCharge, 0);

      currentDir.sub(pos);
      currentDir.normalize();
      currentDir.mult(magnitude);
      dir.add(currentDir);

    }
}
}

Replies(10)

Chrisir

Re: Searching the closest point in a double for loop.

10 months ago

here...

int gridDim = 15;
int numCharges = 3;
float maxStrengthPerCharge = 100/numCharges;
ArrayList <Vector> field = new ArrayList <Vector> ();
ArrayList <Electron> charges = new ArrayList<Electron>();
PVector speed = new PVector();
boolean fullGrid;
float value = 1;
int multi = 400;
void setup() {
size(600, 600);
smooth();
strokeWeight(0.5);
int w = width/gridDim;
int h = height/gridDim;
for (int y = 0; y<gridDim; y++) {
for (int x = 0; x<gridDim; x++) {
field.add(new Vector((x+0.5)*w, (y+0.5)*h));//ARRAY OF GRID POINTS
}
}
resetElectrons();
}
void draw() {
background(255);
for (Electron e : charges) {
e.display();
}
for (Vector v : field) {
v.update();
}
for (int y = 0; y<gridDim*gridDim; y++) {
Vector vec1 = field.get(y);
for (int x = 0; x<gridDim*gridDim; x++) {
Vector vec2 = field.get(x);
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
float distance = dist(vec1.pos.x+(vec1.dir.x)*value/multi, vec1.pos.y+(vec1.dir.y)*value/multi, vec2.pos.x+(vec2.dir.x)*value/multi, vec2.pos.y+(vec2.dir.y)*value/multi);
// float distance = vec1.pos.dist(vec2.pos);
if (distance > 0 && distance< 40) {
stroke(1);
line(vec1.pos.x+(vec1.dir.x)*value/multi, vec1.pos.y+(vec1.dir.y)*value/multi, vec2.pos.x+(vec2.dir.x)*value/multi, vec2.pos.y+(vec2.dir.y)*value/multi);
}
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
ellipse(vec1.pos.x+(vec1.dir.x)*value/multi, vec1.pos.y+(vec1.dir.y)*value/multi, 20, 20);
}
}
move();
}
void move() {
value = 1 + value*0.98;
}
void resetElectrons() {
charges.clear();
for (int i = 0; i<numCharges; i++) {
charges.add(new Electron(400, 400, 20));
charges.add(new Electron(200, 300, 20));
charges.add(new Electron(500, 200, 20));
}
}
class Electron {
PVector pos;
float charge;
Electron(float x, float y, float charge) {
pos = new PVector (x, y);
this.charge=charge;
}
void display() {
pushMatrix();
translate(pos.x, pos.y);
noStroke();
fill(0);
ellipse(0, 0, charge, charge);
popMatrix();
}
}
class Vector {
PVector pos, dir;
Vector(float x, float y) {
pos = new PVector(x, y);
dir = new PVector();
}
void update() {
dir.set(0, 0, 0);
for (Electron e : charges) {
PVector currentDir = e.pos.get();
float magnitude = map(currentDir.dist(pos), 0, width, maxStrengthPerCharge, 0);
currentDir.sub(pos);
currentDir.normalize();
currentDir.mult(magnitude);
dir.add(currentDir);
}
}
}

p3tr4s

Re: Searching the closest point in a double for loop.

10 months ago

It seems that this script makes points - grid points copy on top of each other multiple times.
And if I am right, this is the result why this script becomes so slow.
How can I solve this problem?

amnon.owed

Re: Searching the closest point in a double for loop.

10 months ago

It would make more sense to lose the grid code in draw(), calculate the final position (pos+dir) of each Vector in it's update() method and then add a display() method inside the Vector. The display() method in each Vector goes over all vectors in the list and compares distances with the current Vector. If it's within range it draws a line between the two.

p3tr4s

Re: Searching the closest point in a double for loop.

10 months ago

As I understand the code could go into Vector class?
I tried to deal with variables in Vector class, update method, but the double "for loop" is in draw function.
As a result the display function alsa has to be in Vector class?

I am a bit confused...

Please, explain your idea in script:)

amnon.owed

Re: Searching the closest point in a double for loop.

10 months ago

Remove all the double for loop code. Instead call the new display() method for each Vector.

Add a PVector called fin to your Vector class and add this line at the end of it's update() method:

fin = PVector.add(pos, dir);

Add this display method to your Vector class:

void display() {
fill(0);
ellipse(fin.x, fin.y, 10, 10);
stroke(0);
for (Vector v : field) {
if (v.fin.dist(fin) < 50) {
line(v.fin.x, v.fin.y, fin.x, fin.y);
}
}
}

gediminas..

Re: Searching the closest point in a double for loop.

10 months ago

When you say "call the new display() method for each Vector", you mean something like this?

for (int i = 0; i<field.size(); i++) {
Vector v = (Vector) field.get(i);
v.update();
v.display();
}

When I do this, the gridpoints don't move. I mean it's logical, since I deleted the whole for() loop, which was updating the position of the gridpoints , but how do I redo this with the new display(); method?

The full code:

int gridDim = 20;
int numCharges = 1;
float maxStrengthPerCharge = 100/numCharges;
ArrayList <Vector> field = new ArrayList <Vector> ();
ArrayList <Electron> charges = new ArrayList<Electron>();
ArrayList <Electron_re> chargesre = new ArrayList<Electron_re>();
Attractors[] attractors = new Attractors[1000];

float value = 1;
int multi = 2000;

void setup() {

size(1200, 1000);
smooth();
strokeWeight(0.5);
int w = width/gridDim;
int h = height/gridDim;
for (int y = 0; y<gridDim; y++) {
    for (int x = 0; x<gridDim; x++) {
      field.add(new Vector((x+0.5)*w, (y+0.5)*h));//ARRAY OF GRID POINTS
    }
}

for (int i = 0; i<attractors.length;i++) {
    attractors[i] = new Attractors();
}
resetElectrons();
}

void draw() {
background(255);

for (Electron e : charges) {
    e.display();
}
for (Electron_re er : chargesre) {
    er.display();
}
for (Vector v : field) {
    v.update();
}

value = 1 + value*0.98;///////////FOR MOVING POINTS

for (int i = 0; i<field.size(); i++) {
Vector v = (Vector) field.get(i);
v.update();
v.display();
}

// for (int y = 0; y<gridDim-1; y++) {
//   noFill();
// beginShape(QUAD_STRIP);//QUAD_STRIP FOR MESH
//   for (int x = 0; x<gridDim; x++) {
//     stroke(1);
//     Vector vec1 = field.get(x+y*gridDim);
//     Vector vec2 = field.get(x+(y+1)*gridDim);

// vertex(vec1.pos.x+(vec1.dir.x)*value/multi, vec1.pos.y+(vec1.dir.y)*value/multi);
//   vertex(vec2.pos.x+(vec2.dir.x)*value/multi, vec2.pos.y+(vec2.dir.y)*value/multi);

     // ellipse(vec2.pos.x+(vec2.dir.x)*value/multi, vec2.pos.y+(vec2.dir.y)*value/multi, 5, 5);
//    }
// }
// endShape();
}

void resetElectrons() {
charges.clear();
for (int i = 0; i<numCharges; i++) {

    String[] Hotels = loadStrings("Hotels.txt"); //-
    String[] Blokados = loadStrings("Blokados.txt"); //+

    for (int j = 0; j<attractors.length; j++) {

      if (j<Hotels.length) {
        float[] H = float(split(Hotels[j], "," ));
        chargesre.add(new Electron_re(H[0], 1000-H[1], 10));
      }

     if (j<Blokados.length) {
       float[] B = float(split(Blokados[j], "," ));
      charges.add(new Electron(B[0], 1000-B[1], 10));
    }
      //   charges.add(new Electron(300, 100, 20));
      // charges.add(new Electron(200, 400, 20));
      // charges.add(new Electron(400, 200, 20));
      //   chargesre.add(new Electron_re(200, 200, 20));
      // chargesre.add(new Electron_re(300, 300, 20));
      // chargesre.add(new Electron_re(400, 400, 20));
    }
}
}
class Attractors {
float size = 7;
Attractors() {
}
void Hotels(float x1, float y1) {
ellipse(x1, 1000-y1, 7, 7);
}
}
class Electron {
PVector pos;
float charge;

Electron(float x, float y, float charge) {
    pos = new PVector (x, y);
    this.charge=charge;
}
void display() {
    pushMatrix();
    translate(pos.x, pos.y);
    noStroke();
    fill(0);
   ellipse(0, 0, charge, charge);
    popMatrix();
}
}
class Electron_re {
PVector pos;
float charge;

Electron_re(float x, float y, float charge) {
    pos = new PVector (x, y);
    this.charge=charge;
}
void display() {
    pushMatrix();
    translate(pos.x, pos.y);
    noStroke();
    fill(0);
    fill(0,255,0);
    ellipse(0, 0, charge, charge);
    popMatrix();
}
}
class Vector {
PVector pos, dir, fin;

Vector(float x, float y) {
    pos = new PVector(x, y);
    dir = new PVector();
    fin = PVector.add(pos, dir);
}

void update() {

    dir.set(0, 0, 0);
    for (Electron e : charges) {
      PVector currentDir = e.pos.get();
      float magnitude = map(currentDir.dist(pos), 0, width, maxStrengthPerCharge, 0);

      float positivemagnitude = abs(magnitude);
      if (positivemagnitude<25) {
        positivemagnitude=positivemagnitude*0.75;
      }
    if (positivemagnitude>70) {
      positivemagnitude=70;
    }
//println(positivemagnitude>90);
      currentDir.sub(pos);
      currentDir.normalize();
      currentDir.mult(-positivemagnitude);
      dir.add(currentDir);
    }
    for (Electron_re er : chargesre) {
      PVector currentDir = er.pos.get();
      float magnitude = map(currentDir.dist(pos), 0, width, maxStrengthPerCharge, 0);

      float positivemagnitude = abs(magnitude);
      if (positivemagnitude<25) {
        positivemagnitude=positivemagnitude*0.75;
      }
    if (positivemagnitude>70) {
      positivemagnitude=70;
    }
//println(positivemagnitude>90);
      currentDir.sub(pos);
      currentDir.normalize();
      currentDir.mult(positivemagnitude);
      dir.add(currentDir);


    }
}

   void display() {
    fill(0);
    ellipse(fin.x, fin.y, 10, 10);
    stroke(0);
    for (Vector v : field) {
      if (v.fin.dist(fin) < 10) {
        line(v.fin.x, v.fin.y, fin.x, fin.y);
      }
    }
}
}

amnon.owed

Re: Searching the closest point in a double for loop.

10 months ago

Using a global value to move everything is a bit strange, especially in an OOP context. But to make things move, you can use it somehow in the Vectors' update() method which ultimately determines the position. Something like the adapted code below.

On a forum related note (assuming you are the user formely known as p3tr4s). Please learn to copy-paste readable code by doing the steps in this order:

Autoformat your code in the PDE with CTRL+T.
Copy-paste code.
Select code.
Press "Insert Code" button.

Then the code will be formatted, have linenumbers and be easy to copy as shown below.

Adapted Code

int gridDim = 15;
int numCharges = 3;
float maxStrengthPerCharge = 100/numCharges;
ArrayList <Vector> field = new ArrayList <Vector> ();
ArrayList <Electron> charges = new ArrayList<Electron>();
float value;
void setup() {
size(600, 600);
smooth();
strokeWeight(0.5);
int w = width/gridDim;
int h = height/gridDim;
for (int y = 0; y<gridDim; y++) {
for (int x = 0; x<gridDim; x++) {
field.add(new Vector((x+0.5)*w, (y+0.5)*h));//ARRAY OF GRID POINTS
}
}
charges.add(new Electron(400, 400, 20));
charges.add(new Electron(200, 300, 20));
charges.add(new Electron(500, 200, 20));
}
void draw() {
background(255);
for (Electron e : charges) { e.display(); }
for (Vector v : field) { v.update(); }
for (Vector v : field) { v.display(); }
value = 0.5+sin(frameCount*0.01);
}
class Electron {
PVector pos;
float charge;
Electron(float x, float y, float charge) {
pos = new PVector (x, y);
this.charge=charge;
}
void display() {
pushMatrix();
translate(pos.x, pos.y);
noStroke();
fill(0);
ellipse(0, 0, charge, charge);
popMatrix();
}
}
class Vector {
PVector pos, dir, fin;
Vector(float x, float y) {
pos = new PVector(x, y);
dir = new PVector();
}
void update() {
dir.set(0, 0, 0);
for (Electron e : charges) {
PVector currentDir = e.pos.get();
float magnitude = map(currentDir.dist(pos), 0, width, maxStrengthPerCharge, 0);
currentDir.sub(pos);
currentDir.normalize();
currentDir.mult(magnitude);
dir.add(currentDir);
dir.mult(value);
fin = PVector.add(pos, dir);
}
}
void display() {
fill(0);
ellipse(fin.x, fin.y, 10, 10);
stroke(0);
for (Vector v : field) {
if (v.fin.dist(fin) < 50) {
line(v.fin.x, v.fin.y, fin.x, fin.y);
}
}
}
}

p3tr4s

Re: Re: Searching the closest point in a double for loop.

9 months ago

Hi,

First of all thank you for the fast and neat script.

Could you help me to change Vector class into "toxiclibs" Vec3D.
Now I am have an error to change get() function as it does not exist in toxiclibs.

class GridPt {
Vec3D loc = new Vec3D();
Vec3D dir = new Vec3D();
Vec3D fin = new Vec3D();

GridPt(float x, float y) {
    loc = new Vec3D(x, y, 0);
    dir = new Vec3D();
}

void update() {

    dir.set(0, 0, 0);

    for (AttPt e : charges) {
    Vec3D currentDir = e.pos.get();
    float magnitude = map(attLoc.distanceTo(loc), 0, width, maxStrengthPerCharge, 0);

      attLoc.sub(loc);
      attLoc.normalize();
      attLoc.scaleSelf(magnitude);

      dir.add(attLoc);
      fin =loc.add(dir);
    }
}

void display() {
    fill(0);
    ellipse(fin.x, fin.y, 10, 10);
    stroke(0);
    for (GridPt v : field) {
      if (v.fin.distanceTo(fin) < 50) {
        line(v.fin.x, v.fin.y, fin.x, fin.y);
      }
    }
}
}

p3tr4s

Re: Re: Searching the closest point in a double for loop.

9 months ago

And Please explain these two lines:

dir.set(0, 0, 0);
PVector currentDir = .loc.get();

PhiLho

Re: Searching the closest point in a double for loop.

9 months ago

Duplicate with https://forum.processing.org/topic/pvector-get-function-into-toxiclibs-vec3d
Avoid asking the same question in two different places.
And take a look at PVector reference.

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