coordinates
// Compute coordinates. Allowable range is a box
// that sits above the X-Z plane and extends +/-5
// in X or Z and 20 in Y. The color is determined
// randomly in red, green, and blue. The cycle time
// is also determined randomly from 1 to 20 seconds.
function addCrystal (value, time, loop) {
sx = Math.floor (Math.random(seed) * 20) + 1;
sz = Math.floor (Math.random(seed) * 10) + 1;
sy = Math.floor (Math.random(seed) * 20)/10 + .1;
xc = (Math.floor (Math.random(seed) * 20 - 10) * 100) / 100;
zc = (Math.floor (Math.random(seed) * 20 - 10) * 100) / 100;
yc = (Math.floor (Math.random(seed) * 12 + 1) * 100) / 100;
rd = (Math.floor (Math.random(seed) * 100)) / 100;
gn = (Math.floor (Math.random(seed) * 100)) / 100;
bl = (Math.floor (Math.random(seed) * 100)) / 100;
tt = (Math.floor (Math.random(seed) * 190)) / 10 + 1;