How to transform String in float : float value = float(cm); ? Help

dmada

Hi everyone,

Currently I make a project for learn how to discuss between sensor and processing. So Processing read correctly the port of arduino ( I can see the value with processing)

My problem it's a cannot use this data for make something ( example I want to hide or show like influenced the opacity of an picture). For influenced the opacity I use a white rect but maybe is not a good idea.

Because ( maybe) I've string informations and for make a "if" I use a float . I search differents things but i'm lost with the differents method to are not very clear. I search to transform "cm" in float var1 for use my if. After I thinking to make a map for transform the data.

        // the code with proximity sensor and "cm" like string value. 


        import cc.arduino.*;
        import org.firmata.*;
        import processing.serial.*;

        Serial myPort;   
        String cm;
        float var1;
         PImage fonds;


        void setup() {

           size(displayWidth, displayHeight); //full screen
          println(Serial.list());
          myPort = new Serial(this, Serial.list()[6], 9600);  // go to read the COM of arduino
         myPort.bufferUntil('\n');
          fonds = loadImage("testu.jpg");
           image(fonds, 0, 0,displayWidth,displayHeight); 

        }

        void draw() {


        while (myPort.available() > 0) { //Continue usb serial
            String cm = myPort.readStringUntil('\n'); // Read port analog
            if(cm!=null) {
             cm = trim(cm);

              float var1 = float(cm); // The problem is here how to transform this value

               var1 = map (var1, 0, 700, 0, 255);
            println(cm); // affichage
            println(var1);

            }                       
        }
        if (var1 > 100){                 // currently he don't read this part
         noStroke();
         fill(255,0);
        rect(0, 0,displayWidth,displayHeight);
        smooth();
        }

        else { 
           noStroke();
         fill(255,10);
        rect(0, 0,displayWidth,displayHeight);
        smooth();
        } 

        }

Sorry for my english if i make some mistake. Thank's Kinds regards

Chrisir

go back edit your post (click on the gear and then on edit) please

then format your code correctly - empty line before and after, highlight / select the entire code and hit ctrl-o

Chrisir

first use your println() to see what values cm / var1 you get from arduino - are they like 0.4, 0.6 etc. or 10,40,60 ?

next make a second sketch without arduino to test your fill().

this complete sketch doesn't work:

size(displayWidth, displayHeight);

noStroke(); 
fill(255, 0);   //  !!!!!!!!!!!!!!!!!!!!!!!!!!!  you need fill(255);  or fill(255, 78); 
rect(0, 0, displayWidth, displayHeight); 
smooth(); 

you need to change the fill() line

you can use a println ("here 12"); within the if-clause to see whether he is getting there at all. When he gets there, and your fill() is wrong, you'll still see nothing

dmada

Currently I have my background picture and just after send play the rect begin progressively full white, I change fill(255,95) without arduino its the same.

The cm value is between 6 and 80 cm so more for value like 10,40,60

I have this message NotaNumber

Chrisir

this part is outside the while-statement

if (var1 > 100){  

hence you are testing only the last var1 not all of them

Hint

in processing (not in the forum) hit ctrl-t. It gives you automatic better indents

dmada

Hep its better but I cannot control the fill of the rect again. The picture go slowly full white but don't come back clear.

I have the same message NaN. Its strange I try to change my map and the if but he make the same speed for add some white.

var1 = map (var1, 0, 30, 0, 255); if (var1 > 28) { noStroke(); fill(255, 95); rect(0, 0, displayWidth, displayHeight); smooth();

Thank's for your patience

Chrisir

message NaN.

in which line?

Chrisir

use ctrl-t

then post your entire code please.

did you put if inside while?

dmada

So now normally the "if" is in the while and for NaN its when he println(var1); So the problem its var1 for NaN.

import cc.arduino.*;
import org.firmata.*;
import processing.serial.*;

Serial myPort;   
String cm;
float var1;
PImage fonds;


void setup() {

  size(displayWidth, displayHeight); //full screen
  println(Serial.list());
  myPort = new Serial(this, Serial.list()[6], 9600);  // go to read the COM of arduino
  myPort.bufferUntil('\n');
  fonds = loadImage("testu.jpg");
  image(fonds, 0, 0, displayWidth, displayHeight);
}

void draw() {


  while (myPort.available() > 0) { //Continue usb serial
    String cm = myPort.readStringUntil('\n'); // Read port analog
    if (cm!=null) {
      cm = trim(cm);

      float var1 = float(cm); // MY problem is here how to transform some value

      var1 = map (var1, 0, 30, 0, 255);
      println(cm); // affichage
      println(var1);


      if (var1 > 30) { 
        noStroke();
        fill(255, 95);
        rect(0, 0, displayWidth, displayHeight);
        smooth();
      } else { 
        noStroke();
        fill(255, 0);
        rect(0, 0, displayWidth, displayHeight);
        smooth();
      }
    }
  }
}

Chrisir

you wrote:

NaN its when he println(var1);

what does println cm give you in this case?

say in line 26 : if (cm!=null && !cm.equals("") ) {

benja

You cannot convert a whole sentence to a number. But if the first part is always the same, you could just remove the first 15 characters from the string and parse the rest.

// this is the original message
String message = "Distance en cm :13\n";

// remove line-breaks
message = trim(message);

// remove the first part
String valueString = message.substring(16);

// convert to integer
int value = int(valueString);

println(value);

But i would actually try to change the arduino-code, and send only the values without the "Distance en cm :"

dmada

Indeed my mistake its to combine sentence and data

So now its functionnal I just need to change some parameters for the map and the background but its ok I go to continue.

Thanks guys !

import cc.arduino.*;
import org.firmata.*;
import processing.serial.*;

Serial myPort;   
String cm;
float var1;
PImage fonds;


void setup() {

  size(displayWidth, displayHeight); //full screen
  println(Serial.list());
  myPort = new Serial(this, Serial.list()[6], 9600);  // go to read the COM of arduino
  myPort.bufferUntil('\n');
  fonds = loadImage("testu.jpg");
  image(fonds, 0, 0, displayWidth, displayHeight);
  fonds.resize(displayWidth, displayHeight);
}

void draw() {

  frameRate(10);
  while (myPort.available() > 0) { //Continue usb serial
    String cm = myPort.readStringUntil('\n'); // Read port analog
    if (cm!=null) {
      cm = trim(cm);

      float var1 = float(cm); // MY problem is here how to transform some value

      var1 = map (var1, 0, 50, 0, 255);
      println(cm); // affichage
      println(var1);


      if (var1 > 170) { 
        noStroke();
        fill(255, 95);
        rect(0, 0, displayWidth, displayHeight);
        smooth();
      } 
      if (var1 < 170) { 
       background(fonds);
       image(fonds, 0, 0, displayWidth, displayHeight);
      }
    }
  }
}

Chrisir

Well done!