git.gag.com Git - debian/openrocket/blob - core/src/net/sf/openrocket/models/atmosphere/InterpolatingAtmosphericModel.java

   1 package net.sf.openrocket.models.atmosphere;
   2
   3 /**
   4  * An abstract atmospheric model that pre-computes the conditions on a number of layers
   5  * and later linearly interpolates the values from between these layers.
   6  *
   7  * @author Sampo Niskanen <sampo.niskanen@iki.fi>
   8  */
   9 public abstract class InterpolatingAtmosphericModel implements AtmosphericModel {
  10         /** Layer thickness of interpolated altitude. */
  11         private static final double DELTA = 500;
  12
  13         private AtmosphericConditions[] levels = null;
  14
  15
  16         public AtmosphericConditions getConditions(double altitude) {
  17                 if (levels == null)
  18                         computeLayers();
  19
  20                 if (altitude <= 0)
  21                         return levels[0];
  22                 if (altitude >= DELTA * (levels.length - 1))
  23                         return levels[levels.length - 1];
  24
  25                 int n = (int) (altitude / DELTA);
  26                 double d = (altitude - n * DELTA) / DELTA;
  27                 AtmosphericConditions c = new AtmosphericConditions();
  28                 c.setTemperature(levels[n].getTemperature() * (1 - d) + levels[n + 1].getTemperature() * d);
  29                 c.setPressure(levels[n].getPressure() * (1 - d) + levels[n + 1].getPressure() * d);
  30
  31                 return c;
  32         }
  33
  34
  35         private void computeLayers() {
  36                 double max = getMaxAltitude();
  37                 int n = (int) (max / DELTA) + 1;
  38                 levels = new AtmosphericConditions[n];
  39                 for (int i = 0; i < n; i++) {
  40                         levels[i] = getExactConditions(i * DELTA);
  41                 }
  42         }
  43
  44
  45         protected abstract double getMaxAltitude();
  46
  47         protected abstract AtmosphericConditions getExactConditions(double altitude);
  48 }