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Index › Programming Questions & Help › Syntax Questions › Question about Arrays
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Question about Arrays (Read 644 times)
hndrsn
Question about Arrays
Dec 6th, 2009, 9:54am  
Hello folks,

I've been working on a sketch using an array to store a mouseX position to determine the radius of a circle (in the final code I will be using the serial port to read input from an arduino instead of mouseX). The problem is that I want to create an unbroken line linking each new point to the previous point in the array - I presume there's a relatively simple fix that I'm missing?

Here's my code:
Code:
float[] xpos = new float[120];
float[] ypos = new float[120];

float r = 0.0;

void setup(){
  size(500, 500);
  smooth();

  for (int i = 0; i<xpos.length; i++){
    xpos[i] = 0;
    ypos[i] = 0;
  }
}

void draw(){
  r = map(millis()*0.05, 0, 100, 0, TWO_PI);
  float rx = sin(r)*mouseX+width/2;
  float ry = cos(r)*mouseX+height/2;

  background(0);

  for (int i = 0; i<xpos.length-1; i++){
    xpos[i] = xpos[i+1];
    ypos[i] = ypos[i+1];
  }

  xpos[xpos.length-1] = rx;
  ypos[ypos.length-1] = ry;

  for (int i = 0; i<xpos.length-1; i++){
    stroke(255);
    noFill();
    line(xpos[i], ypos[i], xpos[i], ypos[i]);
  }
}


Thanks in advance! Smiley
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hndrsn
Re: Question about Arrays
Reply #1 - Dec 6th, 2009, 11:59am  
I think I may have fixed it, added a second array [j] I presume that is an appropriate way to solve the problem.

Code:
float[] xpos = new float[120];
float[] ypos = new float[120];

float r = 0.0;

void setup(){
  size(500, 500);
  smooth();

  for (int i = 0; i<xpos.length; i++){
    xpos[i] = 0;
    ypos[i] = 0;
  }
}

void draw(){
  r = map(millis()*0.05, 0, 100, 0, TWO_PI);
  float rx = sin(r)*mouseX+width/2;
  float ry = cos(r)*mouseX+height/2;

  background(0);
  stroke(255);
  noFill();

  for (int i = 0; i<xpos.length-1; i++){
    xpos[i] = xpos[i+1];
    ypos[i] = ypos[i+1];
  }

  xpos[xpos.length-1] = rx;
  ypos[ypos.length-1] = ry;
  
  beginShape(LINES);
  for (int i = 0; i<xpos.length-1; i++){
    vertex(xpos[i], ypos[i]);
  }
  for (int j = 0; j<xpos.length; j++){
    vertex(xpos[j], ypos[j]);
  }
  endShape();
}
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blindfish
Re: Question about Arrays
Reply #2 - Dec 6th, 2009, 12:16pm  
No need for the second array - needs improving but this should give you the idea:

Code:
float[] xpos = new float[120];
float[] ypos = new float[120];

float r = 0.0;

void setup(){
  size(500, 500);
  smooth();

  for (int i = 0; i<xpos.length; i++){
    xpos[i] = 0;
    ypos[i] = 0;
  }
}

void draw(){
  r = map(millis()*0.05, 0, 100, 0, TWO_PI);
  float rx = sin(r)*mouseX+width/2;
  float ry = cos(r)*mouseX+height/2;

  background(0);
  stroke(255);
  noFill();
  
  for (int i = 0; i<xpos.length-1; i++){
    xpos[i] = xpos[i+1];
    ypos[i] = ypos[i+1];
  }

  xpos[xpos.length-1] = rx;
  ypos[ypos.length-1] = ry;

  for (int i = 1; i<xpos.length; i++){
    line(xpos[i-1], ypos[i-1], xpos[i], ypos[i]);
  }
}
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Where is the what if the what is in why?
 
hndrsn
Re: Question about Arrays
Reply #3 - Dec 7th, 2009, 1:14am  
I honestly thought I tried that already!! I must have been half asleep or something. Thanks!

//Screws head on properly
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