/**
* calculates z and adjusts for border conditions
*
* @param x
* @param y
* @return
*/
private float calculateZ(float x, float y) {
float z = 0;
z = 1 - x * x - y * y;
if (z > 0) {
z = (float) Math.sqrt(z);
} else {
z = 0;
}
return z;
}
