Compare the angle between several spinning objects

Processing Coding Questions
1

Hello dear community,

I made a grid of spinning lines. Now I wonder how to know when a line and is neighbours are matching in the vertical or horizontal axis to change theris colors for that moment in which the share the same position.

Here is the code I have so far for better understanding of what I need to accomplish.

Many thanks in advance!

Pulsar[] pulsars; 

int columns = 5;
int rows = 5;
int total = columns*rows;

float stepX, stepY;

void setup() {

  size(500, 500);
  strokeWeight(2);
  
  stepX = width/ columns;
  stepY = height/ rows;

  pulsars = new Pulsar[total];

  int index = 0;
  for (int j = 0; j < rows; j++) {
    for (int i = 0; i < columns; i++) {
      // Arrange lines in a grid
      pulsars[index] = new Pulsar(i * stepX +  (stepX/2), j * stepY + (stepY/2));
      
      // update counter
      index ++;      
      //reset counter
      if (index == total) index = 0;
    }
  }
}

void draw() {
  background(10);

  int index = 0;

  for (int j = 0; j < rows; j++) {
    for (int i = 0; i < columns; i++) {
      // new velocity for every line
      float vel = (index + 1) * 0.003;
      
      stroke(255);
      pulsars[index].display(vel);
      
      // update counter
      index ++;      
      //reset counter
      if (index == total) index = 0;
    }
  }
}

// ROTATING OBJECT
class Pulsar {
  float posX, posY, vel;
  float angle = 0;

  Pulsar(float posX_, float posY_) {
    posX = posX_;
    posY = posY_;
  }
  
  void display(float vel) {
    pushMatrix();
    translate(posX, posY);
    rotate(angle);   
   
    // draw forms
    ellipse(0, 0, 4, 4);
    line(-width/(rows*2), 0, height/(rows*2), 0);  
    
    // uopdate angle
    angle += vel;
    popMatrix();
  }
}
2

http://www.jeffreythompson.org/collision-detection/line-line.php ;
but that requires that you know where the lines are!
so instead working with
push / translate / rotate / line(x1,y1,x2,y2) / pop
better work with array for x1,y1,x2,y2 and calculate/fill that by some math first.
( just a idea )

1 Like
3

I was hoping that using the angle rotation were the soulution but the more I think it the more I see is a nonsense.

How many arrays you think I would need? A 2D array like this [[x1, y1, x2, y2], [x3, y3, x4, y4] … ] would be enough?

Thank you @kll!

4

Another question is if I can’t use rotate or any transformation function, cause this wouldn’t works with collision detection, how cant y make them spin?