Martin Rädlinger

Processing Ambient Light Sensor Library

September 10th, 2007 • Processing

Based on Amit Singh experiments with the »Ambient Light Sensor« I developed a JNI (Java Native Interface) for reading the sensor values.

This sensor is built-in in every MacBookPro and is intended for adjusting the keyboards and displays brightness depending on the lighting conditions. The sensors are located under both speaker covers.

Download the Processing-Library lmu.zip and unzip it to the “libraries” folder of your Processing installation. The source code is included in the “src” folder.

methods:

// both sensor values in an array
public static int[] getLMUArray();
 
// left sensor value
public static int getLMULeft();
 
// right sensor value
public static int getLMURight();

example:

import lmu.*; 
 
int lmu_left;
int lmu_right;
float multi;
 
void setup()
{
  size(800,800);
  frameRate(20);
 
  // initial sensor values
  int[] lmu_start = LmuTracker.getLMUArray();
  lmu_left  = lmu_start[0];
  lmu_right = lmu_start[1];
  multi = 255.0 / (lmu_left);
} 
 
void draw()
{
  // get current sensor values
  int[] vals = LmuTracker.getLMUArray();
  int li = (int)(vals[0] * multi);
  int re = (int)(vals[1] * multi);
 
  background(255);
 
  // left sensor
  fill(li);
  rect(0, 0, width/2, height);
 
  // right sensor
  fill(re);
  rect(width/2, 0, width/2, height);
}