2d stereo oscilloscope

chanof

Hi there, I created this simple oscilloscope with point, and i try without result to use line to merge points, i understand i have to store the x,y points of the two stereo channels into an array but i don't understand how, could some one help me about?

Thanks a lot! Gianmaria

kfrajer

This is an example that demonstrates how to plot data points. the concept is that you store the data in a container and then you traverse the container from the first element to the before the last one (Not the last one). The reason is that you connect a point from the [current position] to the [current pos +1]. If you include the last position, then the algorithm would try to access the [last position+1] which generates an out of bounds exception. The code was a modification from a previous post: https://forum.processing.org/two/discussion/comment/88886#Comment_88886

I generate artificial data which then I process(extract) and plot. Notice I am not plotting x vs. y but I am plotting both x and y against (relative) time.

Kf

final int kMAX_DATA_VAL=1024; 
final int kVERTICAL_MARGIN=int(kMAX_DATA_VAL*0.1);

int bSize;  //buffer size
int index =-1;

String globalBuffer;
int[] valuesx;   //Data been displayed on screen
int[] valuesy;


void settings() {
  size(512, 512);
}

void setup()
{
  bSize=width;
  valuesx = new int[bSize];
  valuesy = new int[bSize];

  noSmooth();

  background(87, 36, 124);
  strokeWeight(5);
}


void draw() {

  ////ENABLE NEXT LINE WHEN NO SERIAL EVENTS AVAILABLE
  loadArtificialData();

  surface.setTitle("Index="+index+" time="+millis()/1000+" sec");
  boolean drawNow=processInputData(globalBuffer);

  if (drawNow==true) {
    //Reset background for new data wave
    if ((index)<=1) {
      background(87, 36, 124);
      return;
    }

    drawLine(index, valuesx, -kMAX_DATA_VAL/2, kMAX_DATA_VAL/2, color(255, 25, 25));   
    drawLine(index, valuesy, -kMAX_DATA_VAL/2, kMAX_DATA_VAL/2, color(250, 205, 25));
  }
}


//Returns true when valid data is available
boolean processInputData(String buff) {

  if (buff==null)
    return false;

  float[] mbuff=float(split(buff, ","));

  //Only process data with two tokens, discard anything else
  if (mbuff.length!=2)
    return false;

  index++;
  if (index==bSize)
    index=0;

  valuesx[index] = int(mbuff[0]);
  valuesy[index] = int(mbuff[1]);

  buff=null;  //Reset buffer for next data stream (IMPORTANT!!!)
  return true;
}

//Draws a line from previous index to current index
void drawLine(int idx, int[] data, float LRange, float HRange, color cc) {
  float y1=map(data[idx-1], LRange, HRange, height-kVERTICAL_MARGIN, kVERTICAL_MARGIN);
  float y2=map(data[idx], LRange, HRange, height-kVERTICAL_MARGIN, kVERTICAL_MARGIN);
  stroke(cc);
  line(idx-1, y1, idx, y2);
}

//This function is for testing/debugging purposes
//Loads data generated from a sine wave
//FORMAT: "time,xval,yval"
void loadArtificialData() {
  globalBuffer=str(index)+",";
  globalBuffer+=str(kMAX_DATA_VAL/2*sin(radians(index%width)*2*3.1415/0.8));

  //println(globalBuffer);
}