Mapping function

map.glsl

float map(float value, float start, float end, float newStart, float newEnd) {
  float percent = (value - start) / (end - start);
  if (percent < 0.0) {
    percent = 0.0;
  }
  if (percent > 1.0) {
    percent = 1.0;
  }
  float newValue = newStart + (newEnd - newStart) * percent;
  return newValue;
} 

map.js

function map (value, start, end, newStart, newEnd) {
  var percent = (value - start) / (end - start)
  if (percent < 0) {
    percent = 0
  }
  if (percent > 1) {
    percent = 1
  }
  var newValue = newStart + (newEnd - newStart) * percent
  return newValue
}