package squidpony.squidgrid;
/**
* Used by DetailedMimic to allow different kinds of detail, including differentiating color or map features.
*
* Created by Tommy Ettinger on 6/9/2016.
*/
public interface AestheticDifference {
/**
* Finds the difference between two int values, which implementations of this interface may treat as colors, as
* kinds of map feature, as item placement factors, or various other ways. The difference should be, on average,
* about 1.0 for inputs that have a decent range of values (shades of color as well as changes in hue, etc.).
* <br>
* The original implementation looked something like this, assuming the SquidColorCenter (from the display module,
* not present in squidlib-util) was instantiated earlier for better efficiency:
* <pre>
* SquidColorCenter scc = new SquidColorCenter();
* Color c1 = scc.get(a), c2 = scc.get(b);
* return ((c1.r - c2.r) * (c1.r - c2.r) + (c1.g - c2.g) * (c1.g - c2.g) + (c1.b - c2.b) * (c1.b - c2.b)) / 65536.0;
* </pre>
* @param a an int that may be interpreted in different ways by different implementations
* @param b another int that may be interpreted in different ways by different implementations
* @return the difference between a and b, ideally averaging about 1.0 for most inputs
*/
double difference(int a, int b);
AestheticDifference rgba8888 = new AestheticDifference() {
@Override
public double difference(int a, int b) {
int aa = a >>> 24,
bb = b >>> 24,
t = aa - bb,
sum = t * t;
aa = (a >>> 16) & 0xff;
bb = (b >>> 16) & 0xff;
t = aa - bb;
sum += t * t;
aa = (a >>> 8) & 0xff;
bb = (b >>> 8) & 0xff;
t = aa - bb;
return (sum + t * t) / 65536.0;
}
};
}