// Field of view calculator
// Script written by Dave Fisher - 5/1/99

// Evaluates lens format selection
function ccd_size() {
	if (document.forms['lenscalc'].radio1[0].checked)
		third_format();
	else if (document.forms['lenscalc'].radio1[1].checked)
		half_format();
}

/* UNUSED */ 
function custRound(x, places) {
	// Created 1997 by Brian Risk.  http://members.aol.com/brianrisk
	return (Math.round(x * Math.pow(10, places))) / Math.pow(10, places);
}

// NetCam SC 1.3MP and 5MP (1/2.5")
function third_format() {
	var distance = document.forms['lenscalc'].distance.value;
	var width = document.forms['lenscalc'].width.value;
	var lens_size = document.forms['lenscalc'].lens_size.value;
	var height = document.forms['lenscalc'].height.value;

	if ((distance > 0) && (width > 0) && (height == 0) && (lens_size == 0)) {
		lens_size = distance / width * 5.4;
		height = width * 0.75;
		document.forms['lenscalc'].lens_size.value = lens_size;
		document.forms['lenscalc'].height.value = height;
   	} else if ((distance > 0) && (width == 0) && (height == 0) && (lens_size > 0)) {
		width = distance / lens_size * 5.4;
		height = width * 0.75;
		document.forms['lenscalc'].width.value = width;
		document.forms['lenscalc'].height.value = height;
	} else if ((distance == 0) && (width > 0) && (height == 0) && (lens_size > 0)) {
		distance = width / 5.4 * lens_size;
		height = width * 0.75;
		document.forms['lenscalc'].distance.value = distance;
		document.forms['lenscalc'].height.value = height;
	} else if ((distance == 0) && (width == 0) && (height > 0) && (lens_size > 0)) {
		distance = height / 5.15 * lens_size;
		width = height / 3 * 4;
		document.forms['lenscalc'].distance.value = distance;
		document.forms['lenscalc'].width.value = width;
	} else if ((distance > 0) && (width == 0) && (height > 0) && (lens_size == 0)) {
		width = height / 3 * 4;
		lens_size = distance / width * 5.4;
		document.forms['lenscalc'].width.value = width;
		document.forms['lenscalc'].lens_size.value = lens_size;
	}
}

// NetCam SC 3MP (1/2")
function half_format() {
	var distance = document.forms['lenscalc'].distance.value;
	var width = document.forms['lenscalc'].width.value;
	var lens_size = document.forms['lenscalc'].lens_size.value;
	var height = document.forms['lenscalc'].height.value;

	if ((distance > 0) && (width > 0) && (height == 0) && (lens_size == 0)) {
		lens_size = distance / width * 6.4;
		height = width * 0.75;
		document.forms['lenscalc'].lens_size.value = lens_size;
		document.forms['lenscalc'].height.value = height;
   	} else if ((distance > 0) && (width == 0) && (height == 0) && (lens_size > 0)) {
		width = distance / lens_size * 6.4;
		height = width * 0.75;
		document.forms['lenscalc'].width.value = width;
		document.forms['lenscalc'].height.value = height;
	} else if ((distance == 0) && (width > 0) && (height == 0) && (lens_size > 0)) {
		distance = width / 6.4 * lens_size;
		height = width * 0.75;
		document.forms['lenscalc'].distance.value = distance;
		document.forms['lenscalc'].height.value = height;
	} else if ((distance == 0) && (width == 0) && (height > 0) && (lens_size > 0)) {
		distance = height / 4.8 * lens_size;
		width = height / 3 * 4;
		document.forms['lenscalc'].distance.value = distance;
		document.forms['lenscalc'].width.value = width;
	} else if ((distance > 0) && (width == 0) && (height > 0) && (lens_size == 0)) {
		width = height / 3 * 4;
		lens_size = distance / width * 6.4;
		document.forms['lenscalc'].width.value = width;
		document.forms['lenscalc'].lens_size.value = lens_size;
	}
}