CameraLookAt.bsh

/*
<?xml version='1.0' standalone='yes' ?>
<!-- xml header for scripts & plugin manager -->
<script>
	<name>CameraLookAt</name>
	<author>TroY</author>
	<version>0.1</version>
	<date>2010-07-11</date>
	<description>
Set a camera's view direction. Simply select your camera and the
object to be looked at.


See also: http://www.aoi-board.de/index.php?action=posts&amp;fid=5&amp;tid=922&amp;site=1
    </description>
</script>
*/


// Sort out the objects.
scene = window.getScene();
sel = scene.getSelection();

if (sel.length != 2)
{
	print("Please select a camera and another object.");
	return;
}

cam = null;
obj = null;
if (scene.getObject(sel[0]).getObject() instanceof SceneCamera)
{
	cam = scene.getObject(sel[0]);
	obj = scene.getObject(sel[1]);
}
else
{
	cam = scene.getObject(sel[1]);
	obj = scene.getObject(sel[0]);
}

// Find new view direction.
newzdir = obj.getCoords().getOrigin().minus(
	cam.getCoords().getOrigin());
newzdir.normalize();

// Find new up direction (if newzdir is parallel to Y, then align
// new updir to X -- otherwise align to Y).
if (Math.abs(newzdir.dot(Vec3.vy())) > 0.999)
{
	newupdir = newzdir.cross(Vec3.vx());
	newupdir = newupdir.cross(newzdir);
}
else
{
	newupdir = newzdir.cross(Vec3.vy());
	newupdir = newupdir.cross(newzdir);
}
newupdir.normalize();

// Set the cam's new Z axis.
cam.getCoords().setOrientation(newzdir, newupdir);