/*
 *  splat.sl
 */
surface
splat(color splatcolor = color(1, 1, 1);
      float radius = 1.0,
            amplitude_g = 1.0,
            sigma_g = 0.4,
            amplitude_e = 1.0,
            sigma_e = 0.16,
            percent_g = 1.0,
            exposure = 1.0 )
{
  float r;
  float value, value_g, value_e;
  float percent_e;
  color opacity;

/* Set radius */

  r = (1.0 - t)*radius;

/* Set contribution from gaussian */

  if (percent_g > 0.0) {
    value_g = amplitude_g*exp(-r*r/(sigma_g*sigma_g));
    value_g = value_g*exposure;
    if (value_g > 1.0) value_g = 1.0;
  } else {
    value_g = 0.0;
  }

/* Set contribution from exponential */

  percent_e = 1.0 - percent_g;

  if (percent_e > 0.0) {
    value_e = amplitude_e*exp(-r/sigma_e);
    value_e = value_e*exposure;
    if (value_e > 1.0) value_e = 1.0;
  } else {
    value_e = 0.0;
  }

/* Calculate sum of contributions */

  value = percent_g*value_g + percent_e*value_e;

/* Set opacity */

/*  if (value >= 1.0) {
 *    opacity = color(1, 1, 1);
 *  } else {
 *    opacity = color(1, 1, 1);
 *  }
 */

/* Set output values */

  Ci = splatcolor*value;
  Oi = Ci;

}