Setting map ranges suitably

Processing Electronics (Arduino, etc.)
1

Hello everyone! can some one please explain to me why my map parameters of both Arduino and processing codes are not fluidly animating the array of pngs I have declared and then stopping with an ArrayIndexOutBoundsException error, thank you

Arduino

const int pingPin = 9;


void setup() {

  Serial.begin(9600);

}

void loop() {

  pinMode(pingPin, OUTPUT);
  digitalWrite(pingPin, LOW);
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);
  delayMicroseconds(5);
  digitalWrite(pingPin, LOW);
  
  duration = pulseIn(pingPin, HIGH);
 
  cm = microsecondsToCentimeters(duration);

  int val = map(cm, 0, 32, 0, 600);    
  Serial.println(cm);                                    
  delay(100);

}

long microsecondsToCentimeters(long microseconds) {

  return microseconds / 29 / 2;

}

Processing

import processing.serial.*;

Serial myPort;
String val;

PImage[] Artboard= new PImage[32];

int counter = 0;
PImage img;

int frame ;
float yPos;
int cm;
int intVal;

void setup () {

  size(767, 600);

  String portName = Serial.list()[2];
  myPort = new Serial(this, portName, 9600);
  myPort.bufferUntil ( '\n' );

  frameRate(60);

  Artboard[0]=loadImage("Artboard_1.png");
  Artboard[1]=loadImage("Artboard_2.png");
  Artboard[2]=loadImage("Artboard_3.png");
  Artboard[3]=loadImage("Artboard_4.png");
  Artboard[4]=loadImage("Artboard_5.png");
  Artboard[5]=loadImage("Artboard_6.png");
  Artboard[6]=loadImage("Artboard_7.png");
  Artboard[6]=loadImage("Artboard_8.png");
  Artboard[7]=loadImage("Artboard_9.png");
  Artboard[8]=loadImage("Artboard_10.png");
  Artboard[9]=loadImage("Artboard_11.png");
  Artboard[10]=loadImage("Artboard_12.png");
  Artboard[11]=loadImage("Artboard_13.png");
  Artboard[12]=loadImage("Artboard_14.png");
  Artboard[13]=loadImage("Artboard_15.png");
  Artboard[14]=loadImage("Artboard_16.png");
  Artboard[15]=loadImage("Artboard_17.png");
  Artboard[16]=loadImage("Artboard_18.png");
  Artboard[17]=loadImage("Artboard_19.png");
  Artboard[18]=loadImage("Artboard_20.png");
  Artboard[19]=loadImage("Artboard_21.png");
  Artboard[20]=loadImage("Artboard_22.png");
  Artboard[21]=loadImage("Artboard_23.png");
  Artboard[22]=loadImage("Artboard_24.png");
  Artboard[23]=loadImage("Artboard_25.png");
  Artboard[24]=loadImage("Artboard_26.png");
  Artboard[25]=loadImage("Artboard_28.png");
  Artboard[26]=loadImage("Artboard_29.png");
  Artboard[27]=loadImage("Artboard_30.png");
  Artboard[28]=loadImage("Artboard_31.png");
  Artboard[29]=loadImage("Artboard_32.png");
  Artboard[30]=loadImage("Artboard_33.png");
  Artboard[31]=loadImage("Artboard_34.png");

}

void serialEvent (Serial myPort) {

  yPos  =  float (myPort.readStringUntil ( '\n' ) ) ;  

} 

void draw() {

  background(255, 255, 255);

  frame = (int) map( yPos, 0, 32, 0, height );

  
  println(frame, yPos);
  image(Artboard[frame], 0, 0);
  
}
1 Like
2

you are using frame as an index for Artboard

Hence

frame = (int) map( yPos, 0, 32, 0, Artboard.length-1 );

When yPos is bigger than 32, frame could get bigger than Artboard.length-1, maybe. I think. That could be bad.

Then add

if (frame > Artboard.length-1)
    frame = Artboard.length-1 ;

after the line with map()

Chrisir

1 Like
3

When my previous post doesn’t solve the issue, I would look at this line.

You could add


    myString = myPort.readStringUntil(lf);
    if (myString != null) {
         yPos = float (  myString  ) ; // does this work?
    }

see readStringUntil() / Libraries / Processing.org

2 Likes
4

This works perfectly

  frame = (int) map( yPos, 0, 32, 0, ameba.length-1);

  if (frame > ameba.length-1) 
    frame = ameba.length-1;

but if I flip this order

  frame = (int) map( yPos, 32, 0, 0, ameba.length-1);

because I want the farthest reading of the ultrasonic mapping from first png to last, causes the out bound exception to appear. Adding

  myString = myPort.readStringUntil(lf);
    if (myString != null) {
         yPos = float (  myString  ) ; // does this work?
    }

does not work.

5

The order does matter

   frame = (int) map ( yPos, 32, 0,  ameba.length-1, 0);

   if (frame > ameba.length-1) 
      frame = ameba.length-1;
6

ah, that would give you the same old result… bad.

what about

  frame = (int) map ( yPos,  // value 
  32, 0,     // range 1
  0,  ameba.length-1);    // range 2

  println(frame);   // now this is to debug!   If you get a bound exception, check, what value frame had!

   // check upper and lower bound 
   if (frame > ameba.length-1) 
      frame = ameba.length-1;

   if (frame < 0) 
      frame = 0;