//
//
// Creates a duplicate version of the selected camera, and allows you to change the
// aperture size on the new camera without affecting the horizontal field of view. 
// It does this by modifying the focal length.
//
// Simple but does the job.
//
// To install, copy this script to your maya scripts directory.
// To run, source the script, select a camera and execute the command jpCreateLockedFOVCamera
//
// (PLEASE CONTACT ME IF YOU PLAN TO MODIFY THIS SCRIPT FOR RE-DISTRIBUTION)
//
// jeremy pronk 2004
// webmaster@thereisnoluck.com


global proc jpCreateLockedFOVCamera()
{
	string $oldCam[] = `ls -sl`;
	string $newCam[] = `duplicate -rr $oldCam[0]`;

	string $oldCamShape[] = `listRelatives -c -type "camera" $oldCam[0]`;
	string $newCamShape[] = `listRelatives -c -type "camera" $newCam[0]`;

	addAttr -ln baseFocalLength -at double  $newCamShape[0];
	setAttr -e -keyable true ($newCamShape[0]+".baseFocalLength");
	addAttr -ln baseHorizontalFilmAperture -at double  $newCamShape[0];
	setAttr -e -keyable true ($newCamShape[0]+".baseHorizontalFilmAperture");

	connectAttr -f ( $oldCamShape[0]+".focalLength" ) ( $newCamShape[0]+".baseFocalLength" );
	connectAttr -f ( $oldCamShape[0]+".horizontalFilmAperture" ) ( $newCamShape[0]+".baseHorizontalFilmAperture" );


	string $flExp;
	$flExp += "float $baseFilmbackWidthMM = baseHorizontalFilmAperture * 2.54;\n";
	$flExp += "float $newFilmbackWidth = horizontalFilmAperture * 2.54;\n\n";
	$flExp += "float $hfov = 2 * ( atan( $baseFilmbackWidthMM / 2.0 / baseFocalLength ) );\n";
	$flExp += "focalLength = $newFilmbackWidth / 2.0 / tan( $hfov / 2.0 );\n";
	expression -s $flExp  -o $newCamShape -ae 1 -uc all;


}