//
// Some C code I used to generate the values->colors map. I didn't run this code on the Arduino. I used ideone.com
// and then pasted the output into my arduino code.
 
#include <iostream>
#include <stdint.h>
#include <math.h>
using namespace std;
 
 
 
const int numValues = 64; // number of colors in our output array. This should correspond 
                          // to the max value you want to display.
double breakPoint = log10(numValues)/2.0;
 
//
// Blend two colors together based on the ratio. ratio of 0.0 will be 100% color a and
// ratio of 1.0 will be 100% color b.
uint32_t blend (uint32_t ina, uint32_t inb, double ratio)
{
  int r = (((ina >> 16) & 0xff) * (1.0-ratio)) + (((inb >> 16) & 0xff) * ratio);
  int g = (((ina >> 8) & 0xff) * (1.0-ratio)) + (((inb >> 8) & 0xff) * ratio);
  int b = (((ina >> 0) & 0xff) * (1.0-ratio)) + (((inb >> 0) & 0xff) * ratio);
  return ((r << 16) | (g << 8) | b);
}
 
//
// Scale the intensity of the passed in color. I am using max brightness colors and 
// 0.0 - 1.0 as the scale value.
uint32_t scale (uint32_t ina, double scale_value)
{
  int r = ((ina >> 16) & 0xff) * scale_value;
  int g = ((ina >> 8) & 0xff) * scale_value;
  int b = ((ina >> 0) & 0xff) * scale_value;
  return ((r << 16) | (g << 8) | b);  
}
 
//  
// Fade blue -> green -> red. I've built in a logarithmic response to make it more of a
// dB meter.
int main() { 
  for (int i = 1; i <= numValues; i++)
  {
    double logValue = log10(i);
    double scaleValue = log10(i+2) / log10(numValues+2);
    double ratio = (logValue < breakPoint) ? logValue / breakPoint : (logValue - breakPoint) / breakPoint;
    uint32_t color = 0;
 
    if (logValue < breakPoint)
      color = blend (0x0000ff, 0x00ff00, ratio);
    else
      color = blend (0x00ff00, 0xff0000, ratio);
    color = scale (color, scaleValue);
    cout <<  "0x" << hex << color << ", ";
  }
  return 0; 
}
 

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